Android: Write string to file
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1
i tried to write a string to a specific file but it wont work.
I tried it with this part of code down here but it isn't writing anything in my .txt file
private void writeToFile(String data) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput(Environment.getExternalStorageDirectory()+ "/config/url.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
I don't know why this isn't working, it would be great to receive some help.
android file outputstream asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
add a comment |
1
i tried to write a string to a specific file but it wont work.
I tried it with this part of code down here but it isn't writing anything in my .txt file
private void writeToFile(String data) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput(Environment.getExternalStorageDirectory()+ "/config/url.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
I don't know why this isn't working, it would be great to receive some help.
android file outputstream asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
add a comment |
1
1
1
1
i tried to write a string to a specific file but it wont work.
I tried it with this part of code down here but it isn't writing anything in my .txt file
private void writeToFile(String data) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput(Environment.getExternalStorageDirectory()+ "/config/url.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
I don't know why this isn't working, it would be great to receive some help.
android file outputstream asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
i tried to write a string to a specific file but it wont work.
I tried it with this part of code down here but it isn't writing anything in my .txt file
private void writeToFile(String data) {
try {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput(Environment.getExternalStorageDirectory()+ "/config/url.txt", Context.MODE_PRIVATE));
outputStreamWriter.write(data);
outputStreamWriter.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
I don't know why this isn't working, it would be great to receive some help.
android file outputstream android file outputstream asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
asked Mar 9 '14 at 17:10
EinsteinEinstein
135213
135213
add a comment |
add a comment |
3 Answers
3
active
oldest
votes
3
OpenFileOutput accepts a filename without separators, as written below
Context | Android Developers
So it would be
Writer writer = null;
try {
writer = new OutputStreamWriter(openFileOutput("url.txt", Context.MODE_PRIVATE));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
For a private directory.
Note that there is no such thing as private mode on an external storage.
It is a bad idea to store configuration files on external storage, because
- The file messes folder structure
- The file will not be deleted with the app nor cleared with data
- The file can be deleted by user or removed if the external storage is removable
- The file can be easily accessed and violated by a user.
So what you probably need is what I've said above, but if you really need to write there, the proper way is listed below
Also I don't like hardcoding separators.
Also, if you need a file on an external storage, proper way of creating a File object is
Writer writer = null;
try {
// get config dir
final File configDir = new File(Environment.getExternalStorageDirectory(), "config");
//make sure it's created
configDir.mkdir();
// open a stream
writer = new OutputStreamWriter(new FileOutputStream(new File(configDir, "url.txt")));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
You code is right, but block finally is not call in same case
– a.black13
Mar 9 '14 at 17:43
@SciJoker In what case? fInally is always called whenever first line in try was was called. The only case when it's not called is a crash.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:48
Because a finally block will always be called unless you call System.exit() (or the thread crashes).
– a.black13
Mar 9 '14 at 17:50
Thank you very much Doctoror Drive! This worked for me! I've done this, because on my phone the main folder is the external folder.
– Einstein
Mar 9 '14 at 17:53
@SciJoker never tried this, but calling System.exit() is a bad idea anyway. Especially in a try block.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:55
|
show 2 more comments
0
Try that:
private void writeToFile(String data) {
try {
File dir = new File(Environment.getExternalStorageDirectory().getPath() + "/config/");
if (dir.exists()) {
// do nothing folder already exists
} else {
// make file folder
dir.mkdirs();
}
File statText = new File(Environment.getExternalStorageDirectory()+ "/config/url.txt");
FileOutputStream is = new FileOutputStream(statText);
OutputStreamWriter osw = new OutputStreamWriter(is);
Writer w = new BufferedWriter(osw);
w.write(data);
w.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
answered Mar 9 '14 at 17:13
ottseottse
49958
1
You've forgot to make sure the config dir is created. This can fail. Also you haven't closed the streams.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:28
1
After wrote data to file U must close streams connections
– a.black13
Mar 9 '14 at 17:41
Now everyone should be happy :P
– ottse
Mar 9 '14 at 18:16
add a comment |
0
For this case, especially on Android, the way going for bytes is usually faster.
With this, I solved it by setting up a class which is given the responsibility to deal with reading/writing bytes from/to file through stream.
As far as it's knew generally, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset) can help us to transfer string you want to bytes you need.
To use FileHelper, run as below: FileHelper.getInstance().writeStringToFile(FileHelper.getInstance().createInternalFile("dir_name", "file_name.txt", context), "a string going to be written to /dir_name/file_name.txt", null);
public class FileHelper {
private static final String DEFAULT_DIR_NAME = "AmoFromTaiwan";
private static final int DEFAULT_BUFFER_SIZE = 1024;
private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final int EOF = -1;
private static FileHelper INSTANCE = new FileHelper();
public static FileHelper getInstance() {
return INSTANCE;
}
private boolean isExternalStorageWritable(Context context) {
/*
String state = Environment.getExternalStorageState();
return Environment.MEDIA_MOUNTED.equals(state);
*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
private boolean isExternalStorageReadable(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
@SuppressLint("SimpleDateFormat")
private String generateFileNameBasedOnTimeStamp() {
return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}
public File createExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
Logger.d("... going to access an external dir:" + dir_path);
dir = new File(dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! failed to mkdirs");
return null;
}
}
if (file_name == null) {
file_path = dir_path + File.separator + generateFileNameBasedOnTimeStamp();
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external dir:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File createInternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
dir_path = dir.getAbsolutePath();
Logger.d("... going to access an internal dir:" + dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! mkdirs failed");
return null;
}
}
if (file_name == null) {
file = new File(dir, generateFileNameBasedOnTimeStamp());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File getExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
if (file_name == null) {
file_path = dir_path;
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external file:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
public File getInternalFile(String dir_name, String file_name, Context context) {
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
if (file_name == null) {
file = new File(dir.getAbsolutePath());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
private byte readBytesFromFile(File file) {
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
long file_length;
byte buffer;
int offset = 0;
int next = 0;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
if (file.length() > Integer.MAX_VALUE) {
Logger.e("!!! file length is out of max of int");
return null;
} else {
file_length = file.length();
}
try {
fis = new FileInputStream(file);
//buffer = new byte[(int) file_length];
buffer = new byte[(int) file.length()];
long time_start = System.currentTimeMillis();
while (true) {
Logger.d("... now next:" + next + " and offset:" + offset);
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
next = fis.read(buffer, offset, (buffer.length-offset));
if (next < 0 || offset >= buffer.length) {
Logger.d("... completed to read");
break;
}
offset += next;
}
//if (offset < buffer.length) {
if (offset < (int) file_length) {
Logger.e("!!! not complete to read");
return null;
}
fis.close();
return buffer;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
public byte readBytesFromFile(File file, boolean is_fis_fos_only) {
if (file == null) return null;
if (is_fis_fos_only) {
return readBytesFromFile(file);
}
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
BufferedInputStream bis;
ByteArrayOutputStream bos;
byte buf = new byte[(int) file.length()];
int num_read;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
bos = new ByteArrayOutputStream();
long time_start = System.currentTimeMillis();
while (true) {
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
num_read = bis.read(buf, 0, buf.length); //1024 bytes per call
if (num_read < 0) break;
bos.write(buf, 0, num_read);
}
buf = bos.toByteArray();
fis.close();
bis.close();
bos.close();
return buf;
} catch (FileNotFoundException e) {
e.printStackTrace();
Logger.e("!!! FileNotFoundException");
return null;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
/**
* streams (InputStream and OutputStream) transfer binary data
* if to write a string to a stream, must first convert it to bytes, or in other words encode it
*/
public boolean writeStringToFile(File file, String string, Charset charset) {
if (file == null) return false;
if (string == null) return false;
return writeBytesToFile(file, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset));
}
public boolean writeBytesToFile(File file, byte data) {
if (file == null) return false;
if (data == null) return false;
FileOutputStream fos;
BufferedOutputStream bos;
try {
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
bos.write(data, 0, data.length);
bos.flush();
bos.close();
fos.close();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return false;
}
return true;
}
/**
* io blocks until some input/output is available.
*/
public boolean copy(File source, File destination) {
if (source == null || destination == null) return false;
Logger.d(">>> source:" + source.getAbsolutePath() + ", destination:" + destination.getAbsolutePath());
try {
FileInputStream fis = new FileInputStream(source);
FileOutputStream fos = new FileOutputStream(destination);
byte buffer = new byte[(int) source.length()];
int len;
while (EOF != (len = fis.read(buffer))) {
fos.write(buffer, 0, len);
}
if (true) { //debug
byte copies = readBytesFromFile(destination);
if (copies != null) {
int copy_len = copies.length;
Logger.d("... stream read and write done for " + copy_len + " bytes");
}
}
return destination.length() != 0;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public void list(final String path, final String end, final List<File> files) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
if (file.isDirectory()) {
for (File child : file.listFiles()){
list(child.getAbsolutePath(), end, files);
}
} else if (file.isFile()) {
if (end.equals("")) {
files.add(file);
} else {
if (file.getName().endsWith(end)) files.add(file);
}
}
}
public String splitFileName(File file, String split) {
String path;
String ext;
int lastIndexOfSplit = file.getAbsolutePath().lastIndexOf(split);
if (lastIndexOfSplit < 0) {
path = file.getAbsolutePath();
ext = "";
} else {
path = file.getAbsolutePath().substring(0, lastIndexOfSplit);
ext = file.getAbsolutePath().substring(lastIndexOfSplit);
}
return new String {path, ext};
}
public File rename(File old_file, String new_name) {
if (old_file == null || new_name == null) return null;
Logger.d(">>> old file path:" + old_file.getAbsolutePath() + ", new file name:" + new_name);
File new_file = new File(old_file, new_name);
if (!old_file.equals(new_file)) {
if (new_file.exists()) { //if find out previous file/dir at new path name exists
if (new_file.delete()) {
Logger.d("... succeeded to delete previous file at new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to delete previous file at new abstract path name");
return null;
}
}
if (old_file.renameTo(new_file)) {
Logger.d("... succeeded to rename old file to new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to rename old file to new abstract path name");
}
} else {
Logger.d("... new and old file have the equal abstract path name:" + new_file.getAbsolutePath());
}
return new_file;
}
public boolean remove(final String path, final String end) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
boolean result = false;
if (file.isDirectory()) {
for (File child : file.listFiles()){
result = remove(child.getAbsolutePath(), end);
}
} else if (file.isFile()) {
if (end.equals("")) {
result = file.delete();
} else {
if (file.getName().endsWith(end)) result = file.delete();
}
} else {
Logger.e("!!! child is not file or directory");
}
return result;
}
@TargetApi(Build.VERSION_CODES.O)
public byte readNIOBytesFromFile(String path) throws IOException {
Logger.d(">>> path:" + path);
if (!Files.exists(Paths.get(path), LinkOption.NOFOLLOW_LINKS)) {
Logger.e("!!! file doesn't exists");
return null;
} else {
return Files.readAllBytes(Paths.get(path));
}
}
@TargetApi(Build.VERSION_CODES.O)
public File writeNIOBytesToFile(String dir, String name, byte data) {
Logger.d(">>> dir:" + dir + ", name:" + name);
Path path_dir;
Path path_file;
try {
if (!Files.exists(Paths.get(dir), LinkOption.NOFOLLOW_LINKS)) {
Logger.d("... make a dir");
path_dir = Files.createDirectories(Paths.get(dir));
if (path_dir == null) {
Logger.e("!!! failed to make a dir");
return null;
}
}
path_file = Files.write(Paths.get(name), data);
return path_file.toFile();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
@TargetApi(Build.VERSION_CODES.O)
public void listNIO(final String dir, final String end, final List<File> files) throws IOException {
Logger.d(">>> dir:" + dir + ", end:" + end);
Files.walkFileTree(Paths.get(dir), new FileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
});
}
/**
* recursion
*/
private int factorial (int x) {
if (x > 1) return (x*(factorial(x-1)));
else if (x == 1) return x;
else return 0;
}
}
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
3
OpenFileOutput accepts a filename without separators, as written below
Context | Android Developers
So it would be
Writer writer = null;
try {
writer = new OutputStreamWriter(openFileOutput("url.txt", Context.MODE_PRIVATE));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
For a private directory.
Note that there is no such thing as private mode on an external storage.
It is a bad idea to store configuration files on external storage, because
- The file messes folder structure
- The file will not be deleted with the app nor cleared with data
- The file can be deleted by user or removed if the external storage is removable
- The file can be easily accessed and violated by a user.
So what you probably need is what I've said above, but if you really need to write there, the proper way is listed below
Also I don't like hardcoding separators.
Also, if you need a file on an external storage, proper way of creating a File object is
Writer writer = null;
try {
// get config dir
final File configDir = new File(Environment.getExternalStorageDirectory(), "config");
//make sure it's created
configDir.mkdir();
// open a stream
writer = new OutputStreamWriter(new FileOutputStream(new File(configDir, "url.txt")));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
You code is right, but block finally is not call in same case
– a.black13
Mar 9 '14 at 17:43
@SciJoker In what case? fInally is always called whenever first line in try was was called. The only case when it's not called is a crash.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:48
Because a finally block will always be called unless you call System.exit() (or the thread crashes).
– a.black13
Mar 9 '14 at 17:50
Thank you very much Doctoror Drive! This worked for me! I've done this, because on my phone the main folder is the external folder.
– Einstein
Mar 9 '14 at 17:53
@SciJoker never tried this, but calling System.exit() is a bad idea anyway. Especially in a try block.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:55
|
show 2 more comments
3
OpenFileOutput accepts a filename without separators, as written below
Context | Android Developers
So it would be
Writer writer = null;
try {
writer = new OutputStreamWriter(openFileOutput("url.txt", Context.MODE_PRIVATE));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
For a private directory.
Note that there is no such thing as private mode on an external storage.
It is a bad idea to store configuration files on external storage, because
- The file messes folder structure
- The file will not be deleted with the app nor cleared with data
- The file can be deleted by user or removed if the external storage is removable
- The file can be easily accessed and violated by a user.
So what you probably need is what I've said above, but if you really need to write there, the proper way is listed below
Also I don't like hardcoding separators.
Also, if you need a file on an external storage, proper way of creating a File object is
Writer writer = null;
try {
// get config dir
final File configDir = new File(Environment.getExternalStorageDirectory(), "config");
//make sure it's created
configDir.mkdir();
// open a stream
writer = new OutputStreamWriter(new FileOutputStream(new File(configDir, "url.txt")));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
You code is right, but block finally is not call in same case
– a.black13
Mar 9 '14 at 17:43
@SciJoker In what case? fInally is always called whenever first line in try was was called. The only case when it's not called is a crash.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:48
Because a finally block will always be called unless you call System.exit() (or the thread crashes).
– a.black13
Mar 9 '14 at 17:50
Thank you very much Doctoror Drive! This worked for me! I've done this, because on my phone the main folder is the external folder.
– Einstein
Mar 9 '14 at 17:53
@SciJoker never tried this, but calling System.exit() is a bad idea anyway. Especially in a try block.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:55
|
show 2 more comments
3
3
3
OpenFileOutput accepts a filename without separators, as written below
Context | Android Developers
So it would be
Writer writer = null;
try {
writer = new OutputStreamWriter(openFileOutput("url.txt", Context.MODE_PRIVATE));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
For a private directory.
Note that there is no such thing as private mode on an external storage.
It is a bad idea to store configuration files on external storage, because
- The file messes folder structure
- The file will not be deleted with the app nor cleared with data
- The file can be deleted by user or removed if the external storage is removable
- The file can be easily accessed and violated by a user.
So what you probably need is what I've said above, but if you really need to write there, the proper way is listed below
Also I don't like hardcoding separators.
Also, if you need a file on an external storage, proper way of creating a File object is
Writer writer = null;
try {
// get config dir
final File configDir = new File(Environment.getExternalStorageDirectory(), "config");
//make sure it's created
configDir.mkdir();
// open a stream
writer = new OutputStreamWriter(new FileOutputStream(new File(configDir, "url.txt")));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
OpenFileOutput accepts a filename without separators, as written below
Context | Android Developers
So it would be
Writer writer = null;
try {
writer = new OutputStreamWriter(openFileOutput("url.txt", Context.MODE_PRIVATE));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
For a private directory.
Note that there is no such thing as private mode on an external storage.
It is a bad idea to store configuration files on external storage, because
- The file messes folder structure
- The file will not be deleted with the app nor cleared with data
- The file can be deleted by user or removed if the external storage is removable
- The file can be easily accessed and violated by a user.
So what you probably need is what I've said above, but if you really need to write there, the proper way is listed below
Also I don't like hardcoding separators.
Also, if you need a file on an external storage, proper way of creating a File object is
Writer writer = null;
try {
// get config dir
final File configDir = new File(Environment.getExternalStorageDirectory(), "config");
//make sure it's created
configDir.mkdir();
// open a stream
writer = new OutputStreamWriter(new FileOutputStream(new File(configDir, "url.txt")));
writer.write(data);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) writer.close();
}
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
edited Mar 9 '14 at 17:30
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
answered Mar 9 '14 at 17:15
Yaroslav MytkalykYaroslav Mytkalyk
14.6k96193
14.6k96193
You code is right, but block finally is not call in same case
– a.black13
Mar 9 '14 at 17:43
@SciJoker In what case? fInally is always called whenever first line in try was was called. The only case when it's not called is a crash.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:48
Because a finally block will always be called unless you call System.exit() (or the thread crashes).
– a.black13
Mar 9 '14 at 17:50
Thank you very much Doctoror Drive! This worked for me! I've done this, because on my phone the main folder is the external folder.
– Einstein
Mar 9 '14 at 17:53
@SciJoker never tried this, but calling System.exit() is a bad idea anyway. Especially in a try block.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:55
|
show 2 more comments
You code is right, but block finally is not call in same case
– a.black13
Mar 9 '14 at 17:43
@SciJoker In what case? fInally is always called whenever first line in try was was called. The only case when it's not called is a crash.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:48
Because a finally block will always be called unless you call System.exit() (or the thread crashes).
– a.black13
Mar 9 '14 at 17:50
Thank you very much Doctoror Drive! This worked for me! I've done this, because on my phone the main folder is the external folder.
– Einstein
Mar 9 '14 at 17:53
@SciJoker never tried this, but calling System.exit() is a bad idea anyway. Especially in a try block.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:55
You code is right, but block finally is not call in same case
– a.black13
Mar 9 '14 at 17:43
You code is right, but block finally is not call in same case
– a.black13
Mar 9 '14 at 17:43
@SciJoker In what case? fInally is always called whenever first line in try was was called. The only case when it's not called is a crash.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:48
@SciJoker In what case? fInally is always called whenever first line in try was was called. The only case when it's not called is a crash.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:48
Because a finally block will always be called unless you call System.exit() (or the thread crashes).
– a.black13
Mar 9 '14 at 17:50
Because a finally block will always be called unless you call System.exit() (or the thread crashes).
– a.black13
Mar 9 '14 at 17:50
Thank you very much Doctoror Drive! This worked for me! I've done this, because on my phone the main folder is the external folder.
– Einstein
Mar 9 '14 at 17:53
Thank you very much Doctoror Drive! This worked for me! I've done this, because on my phone the main folder is the external folder.
– Einstein
Mar 9 '14 at 17:53
@SciJoker never tried this, but calling System.exit() is a bad idea anyway. Especially in a try block.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:55
@SciJoker never tried this, but calling System.exit() is a bad idea anyway. Especially in a try block.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:55
|
show 2 more comments
0
Try that:
private void writeToFile(String data) {
try {
File dir = new File(Environment.getExternalStorageDirectory().getPath() + "/config/");
if (dir.exists()) {
// do nothing folder already exists
} else {
// make file folder
dir.mkdirs();
}
File statText = new File(Environment.getExternalStorageDirectory()+ "/config/url.txt");
FileOutputStream is = new FileOutputStream(statText);
OutputStreamWriter osw = new OutputStreamWriter(is);
Writer w = new BufferedWriter(osw);
w.write(data);
w.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
answered Mar 9 '14 at 17:13
ottseottse
49958
1
You've forgot to make sure the config dir is created. This can fail. Also you haven't closed the streams.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:28
1
After wrote data to file U must close streams connections
– a.black13
Mar 9 '14 at 17:41
Now everyone should be happy :P
– ottse
Mar 9 '14 at 18:16
add a comment |
0
Try that:
private void writeToFile(String data) {
try {
File dir = new File(Environment.getExternalStorageDirectory().getPath() + "/config/");
if (dir.exists()) {
// do nothing folder already exists
} else {
// make file folder
dir.mkdirs();
}
File statText = new File(Environment.getExternalStorageDirectory()+ "/config/url.txt");
FileOutputStream is = new FileOutputStream(statText);
OutputStreamWriter osw = new OutputStreamWriter(is);
Writer w = new BufferedWriter(osw);
w.write(data);
w.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
answered Mar 9 '14 at 17:13
ottseottse
49958
1
You've forgot to make sure the config dir is created. This can fail. Also you haven't closed the streams.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:28
1
After wrote data to file U must close streams connections
– a.black13
Mar 9 '14 at 17:41
Now everyone should be happy :P
– ottse
Mar 9 '14 at 18:16
add a comment |
0
0
0
Try that:
private void writeToFile(String data) {
try {
File dir = new File(Environment.getExternalStorageDirectory().getPath() + "/config/");
if (dir.exists()) {
// do nothing folder already exists
} else {
// make file folder
dir.mkdirs();
}
File statText = new File(Environment.getExternalStorageDirectory()+ "/config/url.txt");
FileOutputStream is = new FileOutputStream(statText);
OutputStreamWriter osw = new OutputStreamWriter(is);
Writer w = new BufferedWriter(osw);
w.write(data);
w.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
answered Mar 9 '14 at 17:13
ottseottse
49958
Try that:
private void writeToFile(String data) {
try {
File dir = new File(Environment.getExternalStorageDirectory().getPath() + "/config/");
if (dir.exists()) {
// do nothing folder already exists
} else {
// make file folder
dir.mkdirs();
}
File statText = new File(Environment.getExternalStorageDirectory()+ "/config/url.txt");
FileOutputStream is = new FileOutputStream(statText);
OutputStreamWriter osw = new OutputStreamWriter(is);
Writer w = new BufferedWriter(osw);
w.write(data);
w.close();
}
catch (IOException e) {
Log.e("Exception", "File write failed: " + e.toString());
}
}
answered Mar 9 '14 at 17:13
ottseottse
49958
edited Mar 9 '14 at 18:16
answered Mar 9 '14 at 17:13
ottseottse
49958
answered Mar 9 '14 at 17:13
ottseottse
49958
answered Mar 9 '14 at 17:13
ottseottse
49958
49958
1
You've forgot to make sure the config dir is created. This can fail. Also you haven't closed the streams.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:28
1
After wrote data to file U must close streams connections
– a.black13
Mar 9 '14 at 17:41
Now everyone should be happy :P
– ottse
Mar 9 '14 at 18:16
add a comment |
1
You've forgot to make sure the config dir is created. This can fail. Also you haven't closed the streams.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:28
1
After wrote data to file U must close streams connections
– a.black13
Mar 9 '14 at 17:41
Now everyone should be happy :P
– ottse
Mar 9 '14 at 18:16
1
1
You've forgot to make sure the config dir is created. This can fail. Also you haven't closed the streams.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:28
You've forgot to make sure the config dir is created. This can fail. Also you haven't closed the streams.
– Yaroslav Mytkalyk
Mar 9 '14 at 17:28
1
1
After wrote data to file U must close streams connections
– a.black13
Mar 9 '14 at 17:41
After wrote data to file U must close streams connections
– a.black13
Mar 9 '14 at 17:41
Now everyone should be happy :P
– ottse
Mar 9 '14 at 18:16
Now everyone should be happy :P
– ottse
Mar 9 '14 at 18:16
add a comment |
0
For this case, especially on Android, the way going for bytes is usually faster.
With this, I solved it by setting up a class which is given the responsibility to deal with reading/writing bytes from/to file through stream.
As far as it's knew generally, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset) can help us to transfer string you want to bytes you need.
To use FileHelper, run as below: FileHelper.getInstance().writeStringToFile(FileHelper.getInstance().createInternalFile("dir_name", "file_name.txt", context), "a string going to be written to /dir_name/file_name.txt", null);
public class FileHelper {
private static final String DEFAULT_DIR_NAME = "AmoFromTaiwan";
private static final int DEFAULT_BUFFER_SIZE = 1024;
private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final int EOF = -1;
private static FileHelper INSTANCE = new FileHelper();
public static FileHelper getInstance() {
return INSTANCE;
}
private boolean isExternalStorageWritable(Context context) {
/*
String state = Environment.getExternalStorageState();
return Environment.MEDIA_MOUNTED.equals(state);
*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
private boolean isExternalStorageReadable(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
@SuppressLint("SimpleDateFormat")
private String generateFileNameBasedOnTimeStamp() {
return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}
public File createExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
Logger.d("... going to access an external dir:" + dir_path);
dir = new File(dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! failed to mkdirs");
return null;
}
}
if (file_name == null) {
file_path = dir_path + File.separator + generateFileNameBasedOnTimeStamp();
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external dir:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File createInternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
dir_path = dir.getAbsolutePath();
Logger.d("... going to access an internal dir:" + dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! mkdirs failed");
return null;
}
}
if (file_name == null) {
file = new File(dir, generateFileNameBasedOnTimeStamp());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File getExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
if (file_name == null) {
file_path = dir_path;
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external file:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
public File getInternalFile(String dir_name, String file_name, Context context) {
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
if (file_name == null) {
file = new File(dir.getAbsolutePath());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
private byte readBytesFromFile(File file) {
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
long file_length;
byte buffer;
int offset = 0;
int next = 0;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
if (file.length() > Integer.MAX_VALUE) {
Logger.e("!!! file length is out of max of int");
return null;
} else {
file_length = file.length();
}
try {
fis = new FileInputStream(file);
//buffer = new byte[(int) file_length];
buffer = new byte[(int) file.length()];
long time_start = System.currentTimeMillis();
while (true) {
Logger.d("... now next:" + next + " and offset:" + offset);
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
next = fis.read(buffer, offset, (buffer.length-offset));
if (next < 0 || offset >= buffer.length) {
Logger.d("... completed to read");
break;
}
offset += next;
}
//if (offset < buffer.length) {
if (offset < (int) file_length) {
Logger.e("!!! not complete to read");
return null;
}
fis.close();
return buffer;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
public byte readBytesFromFile(File file, boolean is_fis_fos_only) {
if (file == null) return null;
if (is_fis_fos_only) {
return readBytesFromFile(file);
}
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
BufferedInputStream bis;
ByteArrayOutputStream bos;
byte buf = new byte[(int) file.length()];
int num_read;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
bos = new ByteArrayOutputStream();
long time_start = System.currentTimeMillis();
while (true) {
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
num_read = bis.read(buf, 0, buf.length); //1024 bytes per call
if (num_read < 0) break;
bos.write(buf, 0, num_read);
}
buf = bos.toByteArray();
fis.close();
bis.close();
bos.close();
return buf;
} catch (FileNotFoundException e) {
e.printStackTrace();
Logger.e("!!! FileNotFoundException");
return null;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
/**
* streams (InputStream and OutputStream) transfer binary data
* if to write a string to a stream, must first convert it to bytes, or in other words encode it
*/
public boolean writeStringToFile(File file, String string, Charset charset) {
if (file == null) return false;
if (string == null) return false;
return writeBytesToFile(file, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset));
}
public boolean writeBytesToFile(File file, byte data) {
if (file == null) return false;
if (data == null) return false;
FileOutputStream fos;
BufferedOutputStream bos;
try {
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
bos.write(data, 0, data.length);
bos.flush();
bos.close();
fos.close();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return false;
}
return true;
}
/**
* io blocks until some input/output is available.
*/
public boolean copy(File source, File destination) {
if (source == null || destination == null) return false;
Logger.d(">>> source:" + source.getAbsolutePath() + ", destination:" + destination.getAbsolutePath());
try {
FileInputStream fis = new FileInputStream(source);
FileOutputStream fos = new FileOutputStream(destination);
byte buffer = new byte[(int) source.length()];
int len;
while (EOF != (len = fis.read(buffer))) {
fos.write(buffer, 0, len);
}
if (true) { //debug
byte copies = readBytesFromFile(destination);
if (copies != null) {
int copy_len = copies.length;
Logger.d("... stream read and write done for " + copy_len + " bytes");
}
}
return destination.length() != 0;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public void list(final String path, final String end, final List<File> files) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
if (file.isDirectory()) {
for (File child : file.listFiles()){
list(child.getAbsolutePath(), end, files);
}
} else if (file.isFile()) {
if (end.equals("")) {
files.add(file);
} else {
if (file.getName().endsWith(end)) files.add(file);
}
}
}
public String splitFileName(File file, String split) {
String path;
String ext;
int lastIndexOfSplit = file.getAbsolutePath().lastIndexOf(split);
if (lastIndexOfSplit < 0) {
path = file.getAbsolutePath();
ext = "";
} else {
path = file.getAbsolutePath().substring(0, lastIndexOfSplit);
ext = file.getAbsolutePath().substring(lastIndexOfSplit);
}
return new String {path, ext};
}
public File rename(File old_file, String new_name) {
if (old_file == null || new_name == null) return null;
Logger.d(">>> old file path:" + old_file.getAbsolutePath() + ", new file name:" + new_name);
File new_file = new File(old_file, new_name);
if (!old_file.equals(new_file)) {
if (new_file.exists()) { //if find out previous file/dir at new path name exists
if (new_file.delete()) {
Logger.d("... succeeded to delete previous file at new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to delete previous file at new abstract path name");
return null;
}
}
if (old_file.renameTo(new_file)) {
Logger.d("... succeeded to rename old file to new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to rename old file to new abstract path name");
}
} else {
Logger.d("... new and old file have the equal abstract path name:" + new_file.getAbsolutePath());
}
return new_file;
}
public boolean remove(final String path, final String end) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
boolean result = false;
if (file.isDirectory()) {
for (File child : file.listFiles()){
result = remove(child.getAbsolutePath(), end);
}
} else if (file.isFile()) {
if (end.equals("")) {
result = file.delete();
} else {
if (file.getName().endsWith(end)) result = file.delete();
}
} else {
Logger.e("!!! child is not file or directory");
}
return result;
}
@TargetApi(Build.VERSION_CODES.O)
public byte readNIOBytesFromFile(String path) throws IOException {
Logger.d(">>> path:" + path);
if (!Files.exists(Paths.get(path), LinkOption.NOFOLLOW_LINKS)) {
Logger.e("!!! file doesn't exists");
return null;
} else {
return Files.readAllBytes(Paths.get(path));
}
}
@TargetApi(Build.VERSION_CODES.O)
public File writeNIOBytesToFile(String dir, String name, byte data) {
Logger.d(">>> dir:" + dir + ", name:" + name);
Path path_dir;
Path path_file;
try {
if (!Files.exists(Paths.get(dir), LinkOption.NOFOLLOW_LINKS)) {
Logger.d("... make a dir");
path_dir = Files.createDirectories(Paths.get(dir));
if (path_dir == null) {
Logger.e("!!! failed to make a dir");
return null;
}
}
path_file = Files.write(Paths.get(name), data);
return path_file.toFile();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
@TargetApi(Build.VERSION_CODES.O)
public void listNIO(final String dir, final String end, final List<File> files) throws IOException {
Logger.d(">>> dir:" + dir + ", end:" + end);
Files.walkFileTree(Paths.get(dir), new FileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
});
}
/**
* recursion
*/
private int factorial (int x) {
if (x > 1) return (x*(factorial(x-1)));
else if (x == 1) return x;
else return 0;
}
}
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
add a comment |
0
For this case, especially on Android, the way going for bytes is usually faster.
With this, I solved it by setting up a class which is given the responsibility to deal with reading/writing bytes from/to file through stream.
As far as it's knew generally, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset) can help us to transfer string you want to bytes you need.
To use FileHelper, run as below: FileHelper.getInstance().writeStringToFile(FileHelper.getInstance().createInternalFile("dir_name", "file_name.txt", context), "a string going to be written to /dir_name/file_name.txt", null);
public class FileHelper {
private static final String DEFAULT_DIR_NAME = "AmoFromTaiwan";
private static final int DEFAULT_BUFFER_SIZE = 1024;
private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final int EOF = -1;
private static FileHelper INSTANCE = new FileHelper();
public static FileHelper getInstance() {
return INSTANCE;
}
private boolean isExternalStorageWritable(Context context) {
/*
String state = Environment.getExternalStorageState();
return Environment.MEDIA_MOUNTED.equals(state);
*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
private boolean isExternalStorageReadable(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
@SuppressLint("SimpleDateFormat")
private String generateFileNameBasedOnTimeStamp() {
return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}
public File createExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
Logger.d("... going to access an external dir:" + dir_path);
dir = new File(dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! failed to mkdirs");
return null;
}
}
if (file_name == null) {
file_path = dir_path + File.separator + generateFileNameBasedOnTimeStamp();
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external dir:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File createInternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
dir_path = dir.getAbsolutePath();
Logger.d("... going to access an internal dir:" + dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! mkdirs failed");
return null;
}
}
if (file_name == null) {
file = new File(dir, generateFileNameBasedOnTimeStamp());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File getExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
if (file_name == null) {
file_path = dir_path;
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external file:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
public File getInternalFile(String dir_name, String file_name, Context context) {
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
if (file_name == null) {
file = new File(dir.getAbsolutePath());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
private byte readBytesFromFile(File file) {
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
long file_length;
byte buffer;
int offset = 0;
int next = 0;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
if (file.length() > Integer.MAX_VALUE) {
Logger.e("!!! file length is out of max of int");
return null;
} else {
file_length = file.length();
}
try {
fis = new FileInputStream(file);
//buffer = new byte[(int) file_length];
buffer = new byte[(int) file.length()];
long time_start = System.currentTimeMillis();
while (true) {
Logger.d("... now next:" + next + " and offset:" + offset);
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
next = fis.read(buffer, offset, (buffer.length-offset));
if (next < 0 || offset >= buffer.length) {
Logger.d("... completed to read");
break;
}
offset += next;
}
//if (offset < buffer.length) {
if (offset < (int) file_length) {
Logger.e("!!! not complete to read");
return null;
}
fis.close();
return buffer;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
public byte readBytesFromFile(File file, boolean is_fis_fos_only) {
if (file == null) return null;
if (is_fis_fos_only) {
return readBytesFromFile(file);
}
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
BufferedInputStream bis;
ByteArrayOutputStream bos;
byte buf = new byte[(int) file.length()];
int num_read;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
bos = new ByteArrayOutputStream();
long time_start = System.currentTimeMillis();
while (true) {
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
num_read = bis.read(buf, 0, buf.length); //1024 bytes per call
if (num_read < 0) break;
bos.write(buf, 0, num_read);
}
buf = bos.toByteArray();
fis.close();
bis.close();
bos.close();
return buf;
} catch (FileNotFoundException e) {
e.printStackTrace();
Logger.e("!!! FileNotFoundException");
return null;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
/**
* streams (InputStream and OutputStream) transfer binary data
* if to write a string to a stream, must first convert it to bytes, or in other words encode it
*/
public boolean writeStringToFile(File file, String string, Charset charset) {
if (file == null) return false;
if (string == null) return false;
return writeBytesToFile(file, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset));
}
public boolean writeBytesToFile(File file, byte data) {
if (file == null) return false;
if (data == null) return false;
FileOutputStream fos;
BufferedOutputStream bos;
try {
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
bos.write(data, 0, data.length);
bos.flush();
bos.close();
fos.close();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return false;
}
return true;
}
/**
* io blocks until some input/output is available.
*/
public boolean copy(File source, File destination) {
if (source == null || destination == null) return false;
Logger.d(">>> source:" + source.getAbsolutePath() + ", destination:" + destination.getAbsolutePath());
try {
FileInputStream fis = new FileInputStream(source);
FileOutputStream fos = new FileOutputStream(destination);
byte buffer = new byte[(int) source.length()];
int len;
while (EOF != (len = fis.read(buffer))) {
fos.write(buffer, 0, len);
}
if (true) { //debug
byte copies = readBytesFromFile(destination);
if (copies != null) {
int copy_len = copies.length;
Logger.d("... stream read and write done for " + copy_len + " bytes");
}
}
return destination.length() != 0;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public void list(final String path, final String end, final List<File> files) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
if (file.isDirectory()) {
for (File child : file.listFiles()){
list(child.getAbsolutePath(), end, files);
}
} else if (file.isFile()) {
if (end.equals("")) {
files.add(file);
} else {
if (file.getName().endsWith(end)) files.add(file);
}
}
}
public String splitFileName(File file, String split) {
String path;
String ext;
int lastIndexOfSplit = file.getAbsolutePath().lastIndexOf(split);
if (lastIndexOfSplit < 0) {
path = file.getAbsolutePath();
ext = "";
} else {
path = file.getAbsolutePath().substring(0, lastIndexOfSplit);
ext = file.getAbsolutePath().substring(lastIndexOfSplit);
}
return new String {path, ext};
}
public File rename(File old_file, String new_name) {
if (old_file == null || new_name == null) return null;
Logger.d(">>> old file path:" + old_file.getAbsolutePath() + ", new file name:" + new_name);
File new_file = new File(old_file, new_name);
if (!old_file.equals(new_file)) {
if (new_file.exists()) { //if find out previous file/dir at new path name exists
if (new_file.delete()) {
Logger.d("... succeeded to delete previous file at new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to delete previous file at new abstract path name");
return null;
}
}
if (old_file.renameTo(new_file)) {
Logger.d("... succeeded to rename old file to new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to rename old file to new abstract path name");
}
} else {
Logger.d("... new and old file have the equal abstract path name:" + new_file.getAbsolutePath());
}
return new_file;
}
public boolean remove(final String path, final String end) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
boolean result = false;
if (file.isDirectory()) {
for (File child : file.listFiles()){
result = remove(child.getAbsolutePath(), end);
}
} else if (file.isFile()) {
if (end.equals("")) {
result = file.delete();
} else {
if (file.getName().endsWith(end)) result = file.delete();
}
} else {
Logger.e("!!! child is not file or directory");
}
return result;
}
@TargetApi(Build.VERSION_CODES.O)
public byte readNIOBytesFromFile(String path) throws IOException {
Logger.d(">>> path:" + path);
if (!Files.exists(Paths.get(path), LinkOption.NOFOLLOW_LINKS)) {
Logger.e("!!! file doesn't exists");
return null;
} else {
return Files.readAllBytes(Paths.get(path));
}
}
@TargetApi(Build.VERSION_CODES.O)
public File writeNIOBytesToFile(String dir, String name, byte data) {
Logger.d(">>> dir:" + dir + ", name:" + name);
Path path_dir;
Path path_file;
try {
if (!Files.exists(Paths.get(dir), LinkOption.NOFOLLOW_LINKS)) {
Logger.d("... make a dir");
path_dir = Files.createDirectories(Paths.get(dir));
if (path_dir == null) {
Logger.e("!!! failed to make a dir");
return null;
}
}
path_file = Files.write(Paths.get(name), data);
return path_file.toFile();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
@TargetApi(Build.VERSION_CODES.O)
public void listNIO(final String dir, final String end, final List<File> files) throws IOException {
Logger.d(">>> dir:" + dir + ", end:" + end);
Files.walkFileTree(Paths.get(dir), new FileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
});
}
/**
* recursion
*/
private int factorial (int x) {
if (x > 1) return (x*(factorial(x-1)));
else if (x == 1) return x;
else return 0;
}
}
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
add a comment |
0
0
0
For this case, especially on Android, the way going for bytes is usually faster.
With this, I solved it by setting up a class which is given the responsibility to deal with reading/writing bytes from/to file through stream.
As far as it's knew generally, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset) can help us to transfer string you want to bytes you need.
To use FileHelper, run as below: FileHelper.getInstance().writeStringToFile(FileHelper.getInstance().createInternalFile("dir_name", "file_name.txt", context), "a string going to be written to /dir_name/file_name.txt", null);
public class FileHelper {
private static final String DEFAULT_DIR_NAME = "AmoFromTaiwan";
private static final int DEFAULT_BUFFER_SIZE = 1024;
private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final int EOF = -1;
private static FileHelper INSTANCE = new FileHelper();
public static FileHelper getInstance() {
return INSTANCE;
}
private boolean isExternalStorageWritable(Context context) {
/*
String state = Environment.getExternalStorageState();
return Environment.MEDIA_MOUNTED.equals(state);
*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
private boolean isExternalStorageReadable(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
@SuppressLint("SimpleDateFormat")
private String generateFileNameBasedOnTimeStamp() {
return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}
public File createExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
Logger.d("... going to access an external dir:" + dir_path);
dir = new File(dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! failed to mkdirs");
return null;
}
}
if (file_name == null) {
file_path = dir_path + File.separator + generateFileNameBasedOnTimeStamp();
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external dir:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File createInternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
dir_path = dir.getAbsolutePath();
Logger.d("... going to access an internal dir:" + dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! mkdirs failed");
return null;
}
}
if (file_name == null) {
file = new File(dir, generateFileNameBasedOnTimeStamp());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File getExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
if (file_name == null) {
file_path = dir_path;
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external file:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
public File getInternalFile(String dir_name, String file_name, Context context) {
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
if (file_name == null) {
file = new File(dir.getAbsolutePath());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
private byte readBytesFromFile(File file) {
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
long file_length;
byte buffer;
int offset = 0;
int next = 0;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
if (file.length() > Integer.MAX_VALUE) {
Logger.e("!!! file length is out of max of int");
return null;
} else {
file_length = file.length();
}
try {
fis = new FileInputStream(file);
//buffer = new byte[(int) file_length];
buffer = new byte[(int) file.length()];
long time_start = System.currentTimeMillis();
while (true) {
Logger.d("... now next:" + next + " and offset:" + offset);
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
next = fis.read(buffer, offset, (buffer.length-offset));
if (next < 0 || offset >= buffer.length) {
Logger.d("... completed to read");
break;
}
offset += next;
}
//if (offset < buffer.length) {
if (offset < (int) file_length) {
Logger.e("!!! not complete to read");
return null;
}
fis.close();
return buffer;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
public byte readBytesFromFile(File file, boolean is_fis_fos_only) {
if (file == null) return null;
if (is_fis_fos_only) {
return readBytesFromFile(file);
}
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
BufferedInputStream bis;
ByteArrayOutputStream bos;
byte buf = new byte[(int) file.length()];
int num_read;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
bos = new ByteArrayOutputStream();
long time_start = System.currentTimeMillis();
while (true) {
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
num_read = bis.read(buf, 0, buf.length); //1024 bytes per call
if (num_read < 0) break;
bos.write(buf, 0, num_read);
}
buf = bos.toByteArray();
fis.close();
bis.close();
bos.close();
return buf;
} catch (FileNotFoundException e) {
e.printStackTrace();
Logger.e("!!! FileNotFoundException");
return null;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
/**
* streams (InputStream and OutputStream) transfer binary data
* if to write a string to a stream, must first convert it to bytes, or in other words encode it
*/
public boolean writeStringToFile(File file, String string, Charset charset) {
if (file == null) return false;
if (string == null) return false;
return writeBytesToFile(file, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset));
}
public boolean writeBytesToFile(File file, byte data) {
if (file == null) return false;
if (data == null) return false;
FileOutputStream fos;
BufferedOutputStream bos;
try {
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
bos.write(data, 0, data.length);
bos.flush();
bos.close();
fos.close();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return false;
}
return true;
}
/**
* io blocks until some input/output is available.
*/
public boolean copy(File source, File destination) {
if (source == null || destination == null) return false;
Logger.d(">>> source:" + source.getAbsolutePath() + ", destination:" + destination.getAbsolutePath());
try {
FileInputStream fis = new FileInputStream(source);
FileOutputStream fos = new FileOutputStream(destination);
byte buffer = new byte[(int) source.length()];
int len;
while (EOF != (len = fis.read(buffer))) {
fos.write(buffer, 0, len);
}
if (true) { //debug
byte copies = readBytesFromFile(destination);
if (copies != null) {
int copy_len = copies.length;
Logger.d("... stream read and write done for " + copy_len + " bytes");
}
}
return destination.length() != 0;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public void list(final String path, final String end, final List<File> files) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
if (file.isDirectory()) {
for (File child : file.listFiles()){
list(child.getAbsolutePath(), end, files);
}
} else if (file.isFile()) {
if (end.equals("")) {
files.add(file);
} else {
if (file.getName().endsWith(end)) files.add(file);
}
}
}
public String splitFileName(File file, String split) {
String path;
String ext;
int lastIndexOfSplit = file.getAbsolutePath().lastIndexOf(split);
if (lastIndexOfSplit < 0) {
path = file.getAbsolutePath();
ext = "";
} else {
path = file.getAbsolutePath().substring(0, lastIndexOfSplit);
ext = file.getAbsolutePath().substring(lastIndexOfSplit);
}
return new String {path, ext};
}
public File rename(File old_file, String new_name) {
if (old_file == null || new_name == null) return null;
Logger.d(">>> old file path:" + old_file.getAbsolutePath() + ", new file name:" + new_name);
File new_file = new File(old_file, new_name);
if (!old_file.equals(new_file)) {
if (new_file.exists()) { //if find out previous file/dir at new path name exists
if (new_file.delete()) {
Logger.d("... succeeded to delete previous file at new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to delete previous file at new abstract path name");
return null;
}
}
if (old_file.renameTo(new_file)) {
Logger.d("... succeeded to rename old file to new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to rename old file to new abstract path name");
}
} else {
Logger.d("... new and old file have the equal abstract path name:" + new_file.getAbsolutePath());
}
return new_file;
}
public boolean remove(final String path, final String end) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
boolean result = false;
if (file.isDirectory()) {
for (File child : file.listFiles()){
result = remove(child.getAbsolutePath(), end);
}
} else if (file.isFile()) {
if (end.equals("")) {
result = file.delete();
} else {
if (file.getName().endsWith(end)) result = file.delete();
}
} else {
Logger.e("!!! child is not file or directory");
}
return result;
}
@TargetApi(Build.VERSION_CODES.O)
public byte readNIOBytesFromFile(String path) throws IOException {
Logger.d(">>> path:" + path);
if (!Files.exists(Paths.get(path), LinkOption.NOFOLLOW_LINKS)) {
Logger.e("!!! file doesn't exists");
return null;
} else {
return Files.readAllBytes(Paths.get(path));
}
}
@TargetApi(Build.VERSION_CODES.O)
public File writeNIOBytesToFile(String dir, String name, byte data) {
Logger.d(">>> dir:" + dir + ", name:" + name);
Path path_dir;
Path path_file;
try {
if (!Files.exists(Paths.get(dir), LinkOption.NOFOLLOW_LINKS)) {
Logger.d("... make a dir");
path_dir = Files.createDirectories(Paths.get(dir));
if (path_dir == null) {
Logger.e("!!! failed to make a dir");
return null;
}
}
path_file = Files.write(Paths.get(name), data);
return path_file.toFile();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
@TargetApi(Build.VERSION_CODES.O)
public void listNIO(final String dir, final String end, final List<File> files) throws IOException {
Logger.d(">>> dir:" + dir + ", end:" + end);
Files.walkFileTree(Paths.get(dir), new FileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
});
}
/**
* recursion
*/
private int factorial (int x) {
if (x > 1) return (x*(factorial(x-1)));
else if (x == 1) return x;
else return 0;
}
}
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
For this case, especially on Android, the way going for bytes is usually faster.
With this, I solved it by setting up a class which is given the responsibility to deal with reading/writing bytes from/to file through stream.
As far as it's knew generally, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset) can help us to transfer string you want to bytes you need.
To use FileHelper, run as below: FileHelper.getInstance().writeStringToFile(FileHelper.getInstance().createInternalFile("dir_name", "file_name.txt", context), "a string going to be written to /dir_name/file_name.txt", null);
public class FileHelper {
private static final String DEFAULT_DIR_NAME = "AmoFromTaiwan";
private static final int DEFAULT_BUFFER_SIZE = 1024;
private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final int EOF = -1;
private static FileHelper INSTANCE = new FileHelper();
public static FileHelper getInstance() {
return INSTANCE;
}
private boolean isExternalStorageWritable(Context context) {
/*
String state = Environment.getExternalStorageState();
return Environment.MEDIA_MOUNTED.equals(state);
*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
private boolean isExternalStorageReadable(Context context) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (context.checkSelfPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
return true;
} else {
Logger.e("!!! checkSelfPermission() not granted");
return false;
}
} else { //permission is automatically granted on sdk<23 upon installation
return true;
}
}
@SuppressLint("SimpleDateFormat")
private String generateFileNameBasedOnTimeStamp() {
return new SimpleDateFormat("yyyyMMdd_hhmmss").format(new Date()) + ".jpeg";
}
public File createExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
Logger.d("... going to access an external dir:" + dir_path);
dir = new File(dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! failed to mkdirs");
return null;
}
}
if (file_name == null) {
file_path = dir_path + File.separator + generateFileNameBasedOnTimeStamp();
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external dir:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File createInternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
dir_path = dir.getAbsolutePath();
Logger.d("... going to access an internal dir:" + dir_path);
if (!dir.exists()) {
Logger.d("... going to mkdirs:" + dir_path);
if (!dir.mkdirs()) {
Logger.e("!!! mkdirs failed");
return null;
}
}
if (file_name == null) {
file = new File(dir, generateFileNameBasedOnTimeStamp());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... before creating to delete an external dir:" + file.getAbsolutePath());
if (!file.delete()) {
Logger.e("!!! failed to delete file");
return null;
}
}
return file;
}
public File getExternalFile(String dir_name, String file_name, Context context) {
String dir_path;
String file_path;
File file;
if (!isExternalStorageWritable(context)) {
Logger.e("!!! external storage not writable");
return null;
}
if (dir_name == null) {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + DEFAULT_DIR_NAME;
} else {
dir_path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).getAbsolutePath() + File.separator + dir_name;
}
if (file_name == null) {
file_path = dir_path;
} else {
file_path = dir_path + File.separator + file_name;
}
Logger.d("... going to return an external file:" + file_path);
file = new File(file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
public File getInternalFile(String dir_name, String file_name, Context context) {
String file_path;
File dir ;
File file;
if (dir_name == null) {
dir = new ContextWrapper(context).getDir(DEFAULT_DIR_NAME, Context.MODE_PRIVATE);
} else {
dir = new ContextWrapper(context).getDir(dir_name, Context.MODE_PRIVATE);
}
if (file_name == null) {
file = new File(dir.getAbsolutePath());
} else {
file = new File(dir, file_name);
}
file_path = file.getAbsolutePath();
Logger.d("... going to return an internal dir:" + file_path);
if (file.exists()) {
Logger.d("... file exists:" + file.getAbsolutePath());
} else {
Logger.e("!!! file does't exist:" + file.getAbsolutePath());
}
return file;
}
private byte readBytesFromFile(File file) {
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
long file_length;
byte buffer;
int offset = 0;
int next = 0;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
if (file.length() > Integer.MAX_VALUE) {
Logger.e("!!! file length is out of max of int");
return null;
} else {
file_length = file.length();
}
try {
fis = new FileInputStream(file);
//buffer = new byte[(int) file_length];
buffer = new byte[(int) file.length()];
long time_start = System.currentTimeMillis();
while (true) {
Logger.d("... now next:" + next + " and offset:" + offset);
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
next = fis.read(buffer, offset, (buffer.length-offset));
if (next < 0 || offset >= buffer.length) {
Logger.d("... completed to read");
break;
}
offset += next;
}
//if (offset < buffer.length) {
if (offset < (int) file_length) {
Logger.e("!!! not complete to read");
return null;
}
fis.close();
return buffer;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
public byte readBytesFromFile(File file, boolean is_fis_fos_only) {
if (file == null) return null;
if (is_fis_fos_only) {
return readBytesFromFile(file);
}
Logger.d(">>> path:" + file.getAbsolutePath());
FileInputStream fis;
BufferedInputStream bis;
ByteArrayOutputStream bos;
byte buf = new byte[(int) file.length()];
int num_read;
if (!file.exists()) {
Logger.e("!!! file doesn't exists");
return null;
}
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
bos = new ByteArrayOutputStream();
long time_start = System.currentTimeMillis();
while (true) {
if (System.currentTimeMillis() - time_start > 1000) {
Logger.e("!!! left due to time out");
break;
}
num_read = bis.read(buf, 0, buf.length); //1024 bytes per call
if (num_read < 0) break;
bos.write(buf, 0, num_read);
}
buf = bos.toByteArray();
fis.close();
bis.close();
bos.close();
return buf;
} catch (FileNotFoundException e) {
e.printStackTrace();
Logger.e("!!! FileNotFoundException");
return null;
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
/**
* streams (InputStream and OutputStream) transfer binary data
* if to write a string to a stream, must first convert it to bytes, or in other words encode it
*/
public boolean writeStringToFile(File file, String string, Charset charset) {
if (file == null) return false;
if (string == null) return false;
return writeBytesToFile(file, string.getBytes((charset == null) ? DEFAULT_CHARSET:charset));
}
public boolean writeBytesToFile(File file, byte data) {
if (file == null) return false;
if (data == null) return false;
FileOutputStream fos;
BufferedOutputStream bos;
try {
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
bos.write(data, 0, data.length);
bos.flush();
bos.close();
fos.close();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return false;
}
return true;
}
/**
* io blocks until some input/output is available.
*/
public boolean copy(File source, File destination) {
if (source == null || destination == null) return false;
Logger.d(">>> source:" + source.getAbsolutePath() + ", destination:" + destination.getAbsolutePath());
try {
FileInputStream fis = new FileInputStream(source);
FileOutputStream fos = new FileOutputStream(destination);
byte buffer = new byte[(int) source.length()];
int len;
while (EOF != (len = fis.read(buffer))) {
fos.write(buffer, 0, len);
}
if (true) { //debug
byte copies = readBytesFromFile(destination);
if (copies != null) {
int copy_len = copies.length;
Logger.d("... stream read and write done for " + copy_len + " bytes");
}
}
return destination.length() != 0;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public void list(final String path, final String end, final List<File> files) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
if (file.isDirectory()) {
for (File child : file.listFiles()){
list(child.getAbsolutePath(), end, files);
}
} else if (file.isFile()) {
if (end.equals("")) {
files.add(file);
} else {
if (file.getName().endsWith(end)) files.add(file);
}
}
}
public String splitFileName(File file, String split) {
String path;
String ext;
int lastIndexOfSplit = file.getAbsolutePath().lastIndexOf(split);
if (lastIndexOfSplit < 0) {
path = file.getAbsolutePath();
ext = "";
} else {
path = file.getAbsolutePath().substring(0, lastIndexOfSplit);
ext = file.getAbsolutePath().substring(lastIndexOfSplit);
}
return new String {path, ext};
}
public File rename(File old_file, String new_name) {
if (old_file == null || new_name == null) return null;
Logger.d(">>> old file path:" + old_file.getAbsolutePath() + ", new file name:" + new_name);
File new_file = new File(old_file, new_name);
if (!old_file.equals(new_file)) {
if (new_file.exists()) { //if find out previous file/dir at new path name exists
if (new_file.delete()) {
Logger.d("... succeeded to delete previous file at new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to delete previous file at new abstract path name");
return null;
}
}
if (old_file.renameTo(new_file)) {
Logger.d("... succeeded to rename old file to new abstract path name:" + new_file.getAbsolutePath());
} else {
Logger.e("!!! failed to rename old file to new abstract path name");
}
} else {
Logger.d("... new and old file have the equal abstract path name:" + new_file.getAbsolutePath());
}
return new_file;
}
public boolean remove(final String path, final String end) {
Logger.d(">>> path:" + path + ", end:" + end);
File file = new File(path);
boolean result = false;
if (file.isDirectory()) {
for (File child : file.listFiles()){
result = remove(child.getAbsolutePath(), end);
}
} else if (file.isFile()) {
if (end.equals("")) {
result = file.delete();
} else {
if (file.getName().endsWith(end)) result = file.delete();
}
} else {
Logger.e("!!! child is not file or directory");
}
return result;
}
@TargetApi(Build.VERSION_CODES.O)
public byte readNIOBytesFromFile(String path) throws IOException {
Logger.d(">>> path:" + path);
if (!Files.exists(Paths.get(path), LinkOption.NOFOLLOW_LINKS)) {
Logger.e("!!! file doesn't exists");
return null;
} else {
return Files.readAllBytes(Paths.get(path));
}
}
@TargetApi(Build.VERSION_CODES.O)
public File writeNIOBytesToFile(String dir, String name, byte data) {
Logger.d(">>> dir:" + dir + ", name:" + name);
Path path_dir;
Path path_file;
try {
if (!Files.exists(Paths.get(dir), LinkOption.NOFOLLOW_LINKS)) {
Logger.d("... make a dir");
path_dir = Files.createDirectories(Paths.get(dir));
if (path_dir == null) {
Logger.e("!!! failed to make a dir");
return null;
}
}
path_file = Files.write(Paths.get(name), data);
return path_file.toFile();
} catch (IOException e) {
e.printStackTrace();
Logger.e("!!! IOException");
return null;
}
}
@TargetApi(Build.VERSION_CODES.O)
public void listNIO(final String dir, final String end, final List<File> files) throws IOException {
Logger.d(">>> dir:" + dir + ", end:" + end);
Files.walkFileTree(Paths.get(dir), new FileVisitor<Path>() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
Logger.d("... file:" + file.getFileName());
if (end.equals("")) {
files.add(file.toFile());
} else {
if (file.endsWith(end)) files.add(file.toFile());
}
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
Logger.d("... file:" + dir.getFileName());
return FileVisitResult.CONTINUE;
}
});
}
/**
* recursion
*/
private int factorial (int x) {
if (x > 1) return (x*(factorial(x-1)));
else if (x == 1) return x;
else return 0;
}
}
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
edited Nov 22 '18 at 7:34
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
answered Nov 22 '18 at 6:46
牟家宏牟家宏
215
215
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Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
