Semaphore拿到执行权的线程之间是否互斥

java线程之间的控制，使用Semaphore 实现 互斥

下面我们通过Semaphore来实现一个比较好的互斥操作：

package com.zhy.concurrency.semaphore;  

import java.util.concurrent.Semaphore;  

/**
 * 使用信号量机制，实现互斥访问打印机
 *
 *
 */
public class MutexPrint
{  

    /**
     * 定义初始值为1的信号量
     */
    private final Semaphore semaphore = new Semaphore(1);  

    /**
     * 模拟打印操作
     * @param str
     * @throws InterruptedException
     */
    public void print(String str) throws InterruptedException
    {
        //请求许可
        semaphore.acquire();  

        System.out.println(Thread.currentThread().getName()+" enter ...");
        Thread.sleep(1000);
        System.out.println(Thread.currentThread().getName() + "正在打印 ..." + str);
        System.out.println(Thread.currentThread().getName()+" out ...");
        //释放许可
        semaphore.release();
    }  

    public static void main(String[] args)
    {
        final MutexPrint print = new MutexPrint();  

        /**
         * 开启10个线程，抢占打印机
         */
        for (int i = 0; i < 10; i++)
        {
            new Thread()
            {
                public void run()
                {
                    try
                    {
                        print.print("helloworld");
                    } catch (InterruptedException e)
                    {
                        e.printStackTrace();
                    }
                };
            }.start();
        }  

    }  

}

输出结果：

Thread-1 enter ...
Thread-1正在打印 ...helloworld
Thread-1 out ...
Thread-2 enter ...
Thread-2正在打印 ...helloworld
Thread-2 out ...
Thread-0 enter ...
Thread-0正在打印 ...helloworld
Thread-0 out ...
Thread-3 enter ...
Thread-3正在打印 ...helloworld
Thread-3 out ...