Java并发工具类Semaphore应用实例

package com.thread.test.thread;

import java.util.Random;
import java.util.concurrent.*;

/**
 * Semaphore
 * Semaphore维护者一组权限，无实体权限，只是一组代表权限的数字，
 * 每一次执行acquire都会被阻塞，直到获取获取权限，
 * 每一次执行release都会释放权限，唤醒阻塞acquire线程
 *
 * Semaphore通常应用于限制资源访问
 *
 *
 * Created by windwant on 2016/5/27.
 */
public class MySemaphore {

    public static void main(String[] args) {
        Semaphore sp = new Semaphore(5, true);  //公平性 构造函数 true
        ExecutorService es = Executors.newCachedThreadPool();
        Random r = new Random();
        for (int i = 0; i < 10; i++){
            es.execute(new Needer(sp, r.nextInt(10), "needer" + i));
        }
        es.shutdown();
    }
}

class Needer implements Runnable{

    private Semaphore sp;

    private int seconds;

    private String neederName;

    Needer(Semaphore sp, int seconds, String neederName){
        this.sp = sp;
        this.seconds = seconds;
        this.neederName = neederName;
    }

    public void run() {
        try{
            sp.acquire();
            System.out.println("needer " + neederName + " begin, need time: " + seconds + "s");
            long b = System.currentTimeMillis();
            for (int i = 0; i < seconds; i++) {
                Thread.sleep(1000);
                System.out.println("needer: " + neederName + "============" + i + "============");
            }
            long d = System.currentTimeMillis() - b;
            System.out.println("needer " + neederName + " over, executing time: " + TimeUnit.SECONDS.convert(d, TimeUnit.MILLISECONDS));
            sp.release();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

项目地址：https://github.com/windwant/windwant-demo/tree/master/thread-demo