threadsequence.java

Chinaxp 论坛源代码

package org.redsoft.forum.dao;

/**
 * A singleton class that generates a unique id for threads
 *
 * @author Charles Huang
 * @since JDK 1.4
 * @version 1.0
 */

public final class ThreadSequence{

    private static ThreadSequence generator;
    private long uid;
    private ThreadSequence() {
        uid = 0;
    }

    /**
     *  Return a single instance of this class
     *
     *  @return ThreadSequence - A singleton instance
     */
    public final static synchronized ThreadSequence getInstance(){
        if( generator == null ){
            generator = new ThreadSequence();
        }
        return generator;
    }

    /**
     *  Return a unique id
     *
     *  @return long - An unique id for new threads
     */
    public final synchronized long getThreadSequence(){
        uid++;
        long currentTime = System.currentTimeMillis() - 1000000000;
        return uid + currentTime;
    }
}