java并发流程控制(CountDownLatch-CycliBarrier)

1)CountDownLatch 门插销计数器

      1.  启动线程，然后等待线程结束。即常用的主线程等所有子线程结束后再执行的问题。

public static void main(String[] args)throws Exception {

// TODO Auto-generated method stub

final int count=10;

final CountDownLatch completeLatch = new CountDownLatch(count);//定义了门插销的数目是10

for(int i=0;i

Thread thread = new Thread("worker thread"+i){

public void run(){

//do xxxx

completeLatch.countDown();//减少一根门插销

}

};

thread.start();

}

completeLatch.await();//如果门插销还没减完则等待。

}

---

2.启动很多线程，等待通知才能开始

public static void main(String[] args) throws Exception {

// TODO Auto-generated method stub

final CountDownLatch startLatch = new CountDownLatch(1);//定义了一根门插销

for (int i = 0; i < 10; i++) {

Thread thread = new Thread("worker thread" + i) {

public void run() {

try {

startLatch.await();//如果门插销还没减完则等待

} catch (InterruptedException e) {

}

// do xxxx

}

};

thread.start();

}

startLatch.countDown();//减少一根门插销

}

2) CycliBarrier. 等所有线程都达到一个起跑线后才能开始继续运行。

public class CycliBarrierTest implements Runnable {

private CyclicBarrier barrier;

public CycliBarrierTest(CyclicBarrier barrier) {

this.barrier = barrier;

}

public void run() {

//do xxxx;

try {

this.barrier.await();//线程运行至此会检查是否其它线程都到齐了，没到齐就继续等待。到齐了就执行barrier的run函数体里的内容

} catch (Exception e) {

}

}

/**

* @param args

*/

public static void main(String[] args) {

//参数2代表两个线程都达到起跑线才开始一起继续往下执行

CyclicBarrier barrier = new CyclicBarrier(2, new Runnable() {

public void run() {

//do xxxx;

}

});

Thread t1 = new Thread(new CycliBarrierTest(barrier));

Thread t2 = new Thread(new CycliBarrierTest(barrier));

t1.start();

t2.start();

}

}