CountDownLatch 和 executorService的使用

   今天看zookeeper鏈接到zk的客戶端代碼，使用countDownLatch來實現只有鏈接上以後再進行下一步的操做。這裏有個很是有名的柵欄模式的運用，以下圖所示：

等所有都執行完了，才進行下一步；也能夠實現等一個條件知足了，在開始其餘的動做，兩種場景。

import java.util.Random;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.TimeUnit;

class Worker implements Runnable{

public CountDownLatch countDownLatch;

public String name;

public Worker(CountDownLatch countDownLatch, String name) {

super();

this.countDownLatch = countDownLatch;

this.name = name;

}

public void run() {

System.out.println(this.name+":在幹活呢...");

try {

TimeUnit.SECONDS.sleep(new Random().nextInt(10));

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println(this.name+":幹完活了..");

this.countDownLatch.countDown();

}

}

class Boss extends Worker{

public Boss(CountDownLatch countDownLatch, String name) {

super(countDownLatch, name);

}

public void run() {

System.out.println(this.name+":老闆正在等待人幹完活");

try {

this.countDownLatch.await();

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println(this.name+":老闆說所有完成活了.....");

}

}

public class CountDownLatchTest {

public static void main(String[] args){

ExecutorService executorService = Executors.newCachedThreadPool();

CountDownLatch countDownLatch = new CountDownLatch(100);

for(int i=0;i<100;i++){

executorService.execute(new Worker(countDownLatch,"worker"+i));

}

executorService.execute(new Boss(countDownLatch,"Boss..."));

}

}