package com.sitech.util;

import java.io.File;  
import java.net.URI;  
import java.util.Hashtable;  
import java.util.concurrent.locks.ReentrantReadWriteLock;  
  
public class LockFile extends File{  
  
    private static Hashtable<String , ReentrantReadWriteLock> locks = new Hashtable<String , ReentrantReadWriteLock>();  
    private ReentrantReadWriteLock lock = null;  
      
    public LockFile(File arg0, String arg1) {  
        super(arg0, arg1);  
        lock = initLock(this.getAbsolutePath());  
    }  
  
    public LockFile(String arg0, String arg1) {  
        super(arg0, arg1);  
        lock = initLock(this.getAbsolutePath());  
    }  
  
    public LockFile(String arg0) {  
        super(arg0);  
        lock = initLock(this.getAbsolutePath());  
    }  
  
    public LockFile(URI arg0) {  
        super(arg0);  
        lock = initLock(this.getAbsolutePath());  
    }  
      
    /* 
     * 这里要注意使用 static synchronized，不然可能同时有多个进行初始化这个文件 
     */  
    private static synchronized ReentrantReadWriteLock initLock(String path) {  
        ReentrantReadWriteLock lock = locks.get(path);  
        if (lock == null) {  
            lock = new ReentrantReadWriteLock();  
            locks.put(path, lock); 
        }  
        return lock;  
    }  
      
    public ReentrantReadWriteLock getLock() {  
        return lock;  
    }  
}