java.nio.channels.FileLock#close()源码实例Demo

/**
 * Returns if the given {@code file } is used by any process (i.e.
 * has the file open for reading or writing).
 *
 * @param    file to check
 * @return   if the given {@code file } is used by any process
 */
// Todo: Here is a candidate for Windows. Verify that it works
private static FileState stateWindows(@NotNull File file) {
    if (!file.exists()) return FileState.NON_EXISTENT;
    try (RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");
         FileChannel fileChannel = randomAccessFile.getChannel()) {

        final FileLock fileLock = fileChannel.tryLock();
        if (fileLock != null) {
            fileLock.close();
            return FileState.CLOSED;
        }
        return FileState.OPEN;
    } catch (IOException ignored) {
        // Do nothing
    }
    return FileState.UNDETERMINED;
}
 

public static void safeClose(FileLock closeable) {
    if (closeable != null) {
        try {
            if (Build.VERSION.SDK_INT > 18) {
                closeable.close();
            } else {
                closeable.release();
            }
        } catch (Throwable e) {
        }
    }
}
 

synchronized boolean isFree()
{
  if (_lock != null) {
    return false;
  }
  
  if (! Files.isReadable(_path)) {
    return true;
  }
  
  try (FileOutputStream fOs = (FileOutputStream) Files.newOutputStream(_path)) {
    FileLock lock = fOs.getChannel().tryLock();
    
    if (lock != null) {
      lock.close();
      
      return true;
    }
    else {
      return false;
    }
  } catch (Exception e) {
    log.finer(_path + ": isFree " + e);
    log.log(Level.FINEST, e.toString(), e);

    return true;
  }
}
 

private static boolean isLocked(File file) {
	try {
		FileLock lock = IOUtils.getFileLock(file, true);
		if (lock == null)
			return true;
		lock.close();
		return false;
	} catch (IOException e) {
		return true;
	}
}
 

private void useFileChannel() throws IOException {
  File file = File.createTempFile("j2objc", "tmp");
  ChannelGetter channelGetter = new ChannelGetter();

  channelGetter.createChannel(file);
  // The FileOutputStream used to create the channel is released at this point.

  FileChannel channel = channelGetter.get();
  FileLock lock = channel.lock();
  lock.close();
  channel.close();
  assertTrue(file.delete());
}
 

boolean isNotOpenByAnyProcess(@NotNull File file) {
    try (RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");
         FileChannel fileChannel = randomAccessFile.getChannel()) {

        final FileLock fileLock = fileChannel.tryLock();
        if (fileLock != null) {
            fileLock.close();
            return true;
        }
    } catch (IOException ignored) {
    }
    return false;
}