案例1： 100米田径中，裁判员1鸣枪后，运动员跑，后所有运动员到达终点，裁判员2统计结果：
package thread;
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
/**
* 执行结果：
* 倒计时3秒
倒计时2秒
倒计时1秒
裁判员1鸣枪
运动员pool-1-thread-2 begin run
运动员pool-1-thread-4 begin run
运动员pool-1-thread-5 begin run
运动员pool-1-thread-3 begin run
运动员pool-1-thread-2 end run
运动员pool-1-thread-4 end run
运动员pool-1-thread-5 end run
运动员pool-1-thread-3 end run
裁判员2pool-1-thread-6统计完结果
* @author zm
*
*/
public class CountDownLatchTest2 {
/**
* 裁判员1发令结束
* 运动员1,2,3,4开始跑
* 裁判员2在运动员都跑到终点后，统计名词
* ------> 执行阶段性任务
*/
public static void main(String[] args) {
// 因为有三个阶段任务，因此需要两个阶段任务间隔计数器
final CountDownLatch countDownLatch1 = new CountDownLatch(1);
final CountDownLatch countDownLatch2 = new CountDownLatch(4);
ExecutorService service = Executors.newCachedThreadPool();
//0 裁判员线程
service.execute(new Runnable() {
@Override
public void run() {
for(int i=3; i>=1; i--){
try {
TimeUnit.SECONDS.sleep(1);
System.out.println("倒计时" + i + "秒");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("裁判员1鸣枪");
countDownLatch1.countDown();
}
});
// 1 4个运动员线程
for(int i=0; i<4; i++){
Runnable runnable = new Runnable() {
@Override
public void run() {
try {
countDownLatch1.await();
System.out.println("运动员" + Thread.currentThread().getName() + " begin run");
TimeUnit.SECONDS.sleep(new Random().nextInt(3));
System.out.println("运动员" + Thread.currentThread().getName() + " end run");
countDownLatch2.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
service.execute(runnable);
}
// 2 裁判员统计结果
service.execute(new Runnable() {
@Override
public void run() {
try {
countDownLatch2.await();
System.out.println("裁判员2" + Thread.currentThread().getName() + "统计完结果");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
}
package cn.itcast.heima2;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* 计数器线程工具同步类
* @author zm
*
* 线程pool-1-thread-1正准备接受命令
线程pool-1-thread-2正准备接受命令
线程pool-1-thread-3正准备接受命令
线程main即将发布命令
线程main已发送命令，正在等待结果
线程pool-1-thread-1已接受命令
线程pool-1-thread-2已接受命令
线程pool-1-thread-3已接受命令
*
*/
public class CountdownLatchTest {
public static void main(String[] args) {
ExecutorService service = Executors.newCachedThreadPool();
final CountDownLatch cdOrder = new CountDownLatch(1);
final CountDownLatch cdAnswer = new CountDownLatch(3);
for(int i=0;i<3;i++){
Runnable runnable = new Runnable(){
public void run(){
try {
System.out.println("线程" + Thread.currentThread().getName() +
"正准备接受命令");
cdOrder.await();
System.out.println("线程" + Thread.currentThread().getName() +
"已接受命令");
Thread.sleep((long)(Math.random()*10000));
System.out.println("线程" + Thread.currentThread().getName() +
"回应命令处理结果");
cdAnswer.countDown();
} catch (Exception e) {
e.printStackTrace();
}
}
};
service.execute(runnable);
}
try {
Thread.sleep((long)(Math.random()*10000));
System.out.println("线程" + Thread.currentThread().getName() +
"即将发布命令");
cdOrder.countDown();
System.out.println("线程" + Thread.currentThread().getName() +
"已发送命令，正在等待结果");
cdAnswer.await();
System.out.println("线程" + Thread.currentThread().getName() +
"已收到所有响应结果");
} catch (Exception e) {
e.printStackTrace();
}
service.shutdown();
}
}