Java by API/java.nio.channels/FileLock

FileLock: isShared()

   <source lang="java">

import java.io.File; import java.io.RandomAccessFile; import java.nio.channels.FileChannel; import java.nio.channels.FileLock; public class Main {

 public static void main(String[] argv) throws Exception {
   File file = new File("filename");
   FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
   FileLock lock = channel.lock(0, Long.MAX_VALUE, true);
   lock = channel.tryLock(0, Long.MAX_VALUE, true);
   boolean isShared = lock.isShared();
   lock.release();
   channel.close();
 }

}

 </source>
   
  
 
  

FileLock: release()

   <source lang="java">

// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002 // www.BruceEckel.ru. See copyright notice in CopyRight.txt. // Locking portions of a mapped file. import java.io.IOException; import java.io.RandomAccessFile; import java.nio.ByteBuffer; import java.nio.MappedByteBuffer; import java.nio.channels.FileChannel; import java.nio.channels.FileLock; public class Main {

 static final int LENGTH = 0x8FFFFFF; // 128 Mb
 static FileChannel fc;
 public static void main(String[] args) throws Exception {
   fc = new RandomAccessFile("test.dat", "rw").getChannel();
   MappedByteBuffer out = fc.map(FileChannel.MapMode.READ_WRITE, 0, LENGTH);
   for (int i = 0; i < LENGTH; i++)
     out.put((byte) "x");
   new LockAndModify(out, 0, 0 + LENGTH / 3);
   new LockAndModify(out, LENGTH / 2, LENGTH / 2 + LENGTH / 4);
 }
 private static class LockAndModify extends Thread {
   private ByteBuffer buff;
   private int start, end;
   LockAndModify(ByteBuffer mbb, int start, int end) {
     this.start = start;
     this.end = end;
     mbb.limit(end);
     mbb.position(start);
     buff = mbb.slice();
     start();
   }
   public void run() {
     try {
       FileLock fl = fc.lock(start, end, false);
       System.out.println("Locked: " + start + " to " + end);
       while (buff.position() < buff.limit() - 1){
         buff.put((byte) (buff.get() + 1));
       }
       fl.release();
       System.out.println("Released: " + start + " to " + end);
     } catch (IOException e) {
       throw new RuntimeException(e);
     }
   }
 }

}

 </source>