[java][nio]映射文件部分加锁

import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
/**
 * 
 * 对映射文件部分加锁.
 *
 */
public class LockingMappedFiles {

	static final int LENGTH = 0x8ffffff;
	static FileChannel fc;

	public static void main(String[] args) throws Exception {
		fc = new RandomAccessFile("D:\\temp.tmp","rw").getChannel();
		MappedByteBuffer out = fc.map(FileChannel.MapMode.READ_WRITE, 0, LENGTH);
		for(int i = 0; i < LENGTH; i++){
			out.put((byte)i);
		}
		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 (Exception e) {
				throw new RuntimeException(e);
			}
		}
		
	}

}