File	Doc	Category	Size	Date	Package
LockableFileWriter.java	API Doc	Android 1.5 API	11795	Wed May 06 22:42:46 BST 2009	org.apache.commons.io.output

LockableFileWriter

• java.lang.Object
  • java.io.Writer

Fields Summary
private static final String	LCK The extension for the lock file.
private final Writer	out The writer to decorate.
private final File	lockFile The lock file.

Constructors Summary
public LockableFileWriter(String fileName) Constructs a LockableFileWriter. If the file exists, it is overwritten. param fileName the file to write to, not null throws NullPointerException if the file is null throws IOException in case of an I/O error this(fileName, false, null);
public LockableFileWriter(String fileName, boolean append) Constructs a LockableFileWriter. param fileName file to write to, not null param append true if content should be appended, false to overwrite throws NullPointerException if the file is null throws IOException in case of an I/O error this(fileName, append, null);
public LockableFileWriter(String fileName, boolean append, String lockDir) Constructs a LockableFileWriter. param fileName the file to write to, not null param append true if content should be appended, false to overwrite param lockDir the directory in which the lock file should be held throws NullPointerException if the file is null throws IOException in case of an I/O error this(new File(fileName), append, lockDir);
public LockableFileWriter(File file) Constructs a LockableFileWriter. If the file exists, it is overwritten. param file the file to write to, not null throws NullPointerException if the file is null throws IOException in case of an I/O error this(file, false, null);
public LockableFileWriter(File file, boolean append) Constructs a LockableFileWriter. param file the file to write to, not null param append true if content should be appended, false to overwrite throws NullPointerException if the file is null throws IOException in case of an I/O error this(file, append, null);
public LockableFileWriter(File file, boolean append, String lockDir) Constructs a LockableFileWriter. param file the file to write to, not null param append true if content should be appended, false to overwrite param lockDir the directory in which the lock file should be held throws NullPointerException if the file is null throws IOException in case of an I/O error this(file, null, append, lockDir);
public LockableFileWriter(File file, String encoding) Constructs a LockableFileWriter with a file encoding. param file the file to write to, not null param encoding the encoding to use, null means platform default throws NullPointerException if the file is null throws IOException in case of an I/O error this(file, encoding, false, null);
public LockableFileWriter(File file, String encoding, boolean append, String lockDir) Constructs a LockableFileWriter with a file encoding. param file the file to write to, not null param encoding the encoding to use, null means platform default param append true if content should be appended, false to overwrite param lockDir the directory in which the lock file should be held throws NullPointerException if the file is null throws IOException in case of an I/O error super(); // init file to create/append file = file.getAbsoluteFile(); if (file.getParentFile() != null) { FileUtils.forceMkdir(file.getParentFile()); } if (file.isDirectory()) { throw new IOException("File specified is a directory"); } // init lock file if (lockDir == null) { lockDir = System.getProperty("java.io.tmpdir"); } File lockDirFile = new File(lockDir); FileUtils.forceMkdir(lockDirFile); testLockDir(lockDirFile); lockFile = new File(lockDirFile, file.getName() + LCK); // check if locked createLock(); // init wrapped writer out = initWriter(file, encoding, append);

Methods Summary
public void	close() Closes the file writer. throws IOException if an I/O error occurs try { out.close(); } finally { lockFile.delete(); }
private void	createLock() Creates the lock file. throws IOException if we cannot create the file synchronized (LockableFileWriter.class) { if (!lockFile.createNewFile()) { throw new IOException("Can't write file, lock " + lockFile.getAbsolutePath() + " exists"); } lockFile.deleteOnExit(); }
public void	flush() Flush the stream. throws IOException if an I/O error occurs out.flush();
private java.io.Writer	initWriter(java.io.File file, java.lang.String encoding, boolean append) Initialise the wrapped file writer. Ensure that a cleanup occurs if the writer creation fails. param file the file to be accessed param encoding the encoding to use param append true to append return The initialised writer throws IOException if an error occurs boolean fileExistedAlready = file.exists(); OutputStream stream = null; Writer writer = null; try { if (encoding == null) { writer = new FileWriter(file.getAbsolutePath(), append); } else { stream = new FileOutputStream(file.getAbsolutePath(), append); writer = new OutputStreamWriter(stream, encoding); } } catch (IOException ex) { IOUtils.closeQuietly(writer); IOUtils.closeQuietly(stream); lockFile.delete(); if (fileExistedAlready == false) { file.delete(); } throw ex; } catch (RuntimeException ex) { IOUtils.closeQuietly(writer); IOUtils.closeQuietly(stream); lockFile.delete(); if (fileExistedAlready == false) { file.delete(); } throw ex; } return writer;
private void	testLockDir(java.io.File lockDir) Tests that we can write to the lock directory. param lockDir the File representing the lock directory throws IOException if we cannot write to the lock directory throws IOException if we cannot find the lock file if (!lockDir.exists()) { throw new IOException( "Could not find lockDir: " + lockDir.getAbsolutePath()); } if (!lockDir.canWrite()) { throw new IOException( "Could not write to lockDir: " + lockDir.getAbsolutePath()); }
public void	write(int idx) Write a character. param idx the character to write throws IOException if an I/O error occurs out.write(idx);
public void	write(char[] chr) Write the characters from an array. param chr the characters to write throws IOException if an I/O error occurs out.write(chr);
public void	write(char[] chr, int st, int end) Write the specified characters from an array. param chr the characters to write param st The start offset param end The number of characters to write throws IOException if an I/O error occurs out.write(chr, st, end);
public void	write(java.lang.String str) Write the characters from a string. param str the string to write throws IOException if an I/O error occurs out.write(str);
public void	write(java.lang.String str, int st, int end) Write the specified characters from a string. param str the string to write param st The start offset param end The number of characters to write throws IOException if an I/O error occurs out.write(str, st, end);