import java.io.*;
import java.nio.channels.*;

/**
 * 锁住文件（不让其它线程或进程修改）
 *
 * @author kingfish
 */

public class LockFile {
  public LockFile() {
  }

  public static void main(String[] args) throws Exception {

    RandomAccessFile raf = new RandomAccessFile(new File("c:\\test.txt"), "rw");

    FileChannel fc = raf.getChannel();
    FileLock fl = fc.tryLock();

    if (fl.isValid()) {
      System.out.println("get the lock!");

      //测试线程
      new Thread() {
        public void run() {
          while (true) {
            try {
              Thread.sleep(100);
              FileReader fr = new FileReader(new File("c:\\test.txt"));
              int c;
              while ( (c = fr.read()) != -1) {
                System.out.println( (char) c);
              }
              fr.close();
              break;
            }
            catch (Exception e) {
              System.out.println(e);
            }
          }
        }
      }.start();

      //模拟其它操作的耗时：比如用notepad打开无法修改。但是用程序来读写此文件都会异常
      raf.write("kingfish(八百里秦川@龙城异客)".getBytes());
      Thread.sleep(5000);

      fl.release();
      System.out.println("release the lock!");
    }
    raf.close();
  }
}