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