Semaphore 并发工具

 1 package com.thread.test.thread; 2  3 import java.util.Random; 4 import java.util.concurrent.*; 5  6 /** 7  * Semaphore 8  * Semaphore维护者一组权限，无实体权限，只是一组代表权限的数字， 9  * 每一次执行acquire都会被阻塞，直到获取获取权限，10  * 每一次执行release都会释放权限，唤醒阻塞acquire线程11  *12  * Semaphore通常应用于限制资源访问13  *14  *15  * Created by windwant on 2016/5/27.16 */17 public class MySemaphore {18 19   public static void main(String[] args) {20     Semaphore sp = new Semaphore(5, true); //公平性 构造函数 true21     ExecutorService es = Executors.newCachedThreadPool();22     Random r = new Random();23     for (int i = 0; i < 10; i++){24       es.execute(new Needer(sp, r.nextInt(10), "needer" + i));25     }26     es.shutdown();27   }28 }29 30 class Needer implements Runnable{31 32   private Semaphore sp;33 34   private int seconds;35 36   private String neederName;37 38   Needer(Semaphore sp, int seconds, String neederName){39     this.sp = sp;40     this.seconds = seconds;41     this.neederName = neederName;42   }43 44   public void run() {45     try{46       sp.acquire();47       System.out.println("needer " + neederName + " begin, need time: " + seconds + "s");48       long b = System.currentTimeMillis();49       for (int i = 0; i < seconds; i++) {50         Thread.sleep(1000);51         System.out.println("needer: " + neederName + "============" + i + "============");52       }53       long d = System.currentTimeMillis() - b;54       System.out.println("needer " + neederName + " over, executing time: " + TimeUnit.SECONDS.convert(d, TimeUnit.MILLISECONDS));55       sp.release();56     } catch (InterruptedException e) {57       e.printStackTrace();58     }59   }60 }

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原标题：Semaphore 并发工具

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