java多线程编程之CountDownLatch

最新推荐文章于 2025-08-15 22:56:20 发布

转载最新推荐文章于 2025-08-15 22:56:20 发布 · 62 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/fengfengtk/p/5978174.html

文章标签：

#java

本文通过两个具体示例详细解析了 Java 并发包中 CountDownLatch 类的使用方法，包括其核心方法 countDown 和 await 的应用，并展示了如何利用 ExecutorService 来启动多个线程并等待它们全部完成。

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java.util.concurrent.CountDownLatch这个类里面的主要方法为：

1.countDown()，Decrements the count of the latch, releasing all waiting threads if the count reaches zero.

2.await(),Causes the current thread to wait until the latch has counted down to zero, unless the thread is interrupted.

//Runner.java
package com.cc;
import java.util.concurrent.CountDownLatch;

public class Runner implements Runnable{
	private CountDownLatch latch;
	private int index;

	public Runner(int index){
		this.index = index;
	}
	
	public Runner(CountDownLatch latch, int index){
		this.latch = latch;
		this.index = index;
	}
	@Override
	public void run() {
		// TODO Auto-generated method stub
		try {
			Thread.sleep(10);
			latch.countDown();
			System.out.println("latch countDown :"+this.index);
		} catch (InterruptedException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println("latch countDown:"+this.index+"end");
	}
	public CountDownLatch getLatch() {
		return latch;
	}
	public void setLatch(CountDownLatch latch) {
		this.latch = latch;
	}

}


//test.java
package com.cc;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
public class test {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		CountDownLatch latch = new CountDownLatch(10);
		ExecutorService execServ = Executors.newFixedThreadPool(10);
		for (int i = 0; i < 10; i++) {
			execServ.submit(new Runner(latch, i));
		}
		try {
			Thread.sleep(1);
			latch.await();
			System.out.println("latch await through pass");
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println("--end--");
	}

}

//Runner.java
package com.cc;
import java.util.concurrent.CountDownLatch;

public class Runner implements Runnable{
	private CountDownLatch latch;
	private CountDownLatch backLatch;
	private int index;

	public Runner(int index){
		this.index = index;
	}
	
	public Runner(CountDownLatch latch, CountDownLatch backLatch, int index){
		this.latch = latch;
		this.backLatch = backLatch;
		this.index = index;
	}
	@Override
	public void run() {
		// TODO Auto-generated method stub
		try {
			System.out.println("latch countDown :"+this.index);
			latch.countDown();
			System.out.println("latch:"+this.index);
			backLatch.await();
		} catch (InterruptedException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		
		System.out.println("latch countDown:"+this.index+"end");
	}
	public CountDownLatch getLatch() {
		return latch;
	}
	public void setLatch(CountDownLatch latch) {
		this.latch = latch;
	}

	public CountDownLatch getBackLatch() {
		return backLatch;
	}

	public void setBackLatch(CountDownLatch backLatch) {
		this.backLatch = backLatch;
	}

}

//Test.java
package com.cc;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
public class Test {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		CountDownLatch latch = new CountDownLatch(10);
		CountDownLatch backLatch = new CountDownLatch(1);
		ExecutorService execServ = Executors.newFixedThreadPool(10);
		for (int i = 0; i < 10; i++) {
			execServ.submit(new Runner(latch, backLatch,i));
		}
		try {
			latch.await();
			System.out.println("latch await through pass");
			backLatch.countDown();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println("--end--");
	}

}

转载于:https://www.cnblogs.com/fengfengtk/p/5978174.html