/*** CountDownLatch的典型用法2* 代码功能：使用多个下载线程实现下载，等到所有任务完成后合并线程开始合并。* * @author lp**/
public class CountDownLatchDemo2 {public static void main(String[] args) throws InterruptedException {int N = 8;CountDownLatch startSignal = new CountDownLatch(1);//startSignal控制开始CountDownLatch doneSignal = new CountDownLatch(N);//
ExecutorService executor = Executors.newFixedThreadPool(N + 1);// 8个下载线程，1个合并线程// let all threads proceed
        startSignal.countDown();// N个下载任务开始执行for (int i = 0; i < N; ++i) {executor.execute(new DownloadRunnable(startSignal,doneSignal, i));}// wait for all to finishdoneSignal.await();//阻塞，直到计数器为0// 执行合并任务executor.execute(new MergeRunnable());executor.shutdown();}
}/*** 下载线程*/
class DownloadRunnable implements Runnable {private final CountDownLatch startSignal;private final CountDownLatch doneSignal;private final int i;public DownloadRunnable(CountDownLatch startSignal, CountDownLatch doneSignal, int i) {this.startSignal = startSignal;this.doneSignal = doneSignal;this.i = i;}public void run() {try {startSignal.await();//当前线程等待
            doDownload(i);doneSignal.countDown();} catch (InterruptedException e) {e.printStackTrace();}}private void doDownload(int i) {System.out.println("Thead:" + i + "下载完成");}
}

/*** CountDownLatch的典型用法1* 代码功能：模拟多线程下载功能-使用多个下载线程实现下载，等到所有任务完成后合并线程开始合并。* * @author lp**/
public class CountDownLatchDemo {public static void main(String[] args) throws InterruptedException {int N = 8;CountDownLatch doneSignal = new CountDownLatch(N);// 计数器从N开始倒数ExecutorService executor = Executors.newFixedThreadPool(N + 1);// N个下载线程，1个合并线程// N个下载任务开始执行for (int i = 0; i < N; ++i) {executor.execute(new DownloadRunnable(doneSignal, i));}// wait for all to finishdoneSignal.await();//阻塞，直到计数器为0// 执行合并任务executor.execute(new MergeRunnable());executor.shutdown();}
}/*** 下载线程*/
class DownloadRunnable implements Runnable {private final CountDownLatch doneSignal;private final int i;DownloadRunnable(CountDownLatch doneSignal, int i) {this.doneSignal = doneSignal;this.i = i;}public void run() {doDownload(i);doneSignal.countDown();}private void doDownload(int i) {System.out.println("Thead:" + i + "下载完成");}
}/*** 合并线程*/
class MergeRunnable implements Runnable{@Overridepublic void run() {doMerge();}private void doMerge(){System.out.println("合并线程完成合并");}}