JDK1.5 CountDownLatch
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2022-05-28 18:24:33
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/*
* 还有一个利用场景: 应用启动的时候 ,检查所有的服务是否正确启动,如果正确启动,应用程序就可以启动成功.
**/
* 还有一个利用场景: 应用启动的时候 ,检查所有的服务是否正确启动,如果正确启动,应用程序就可以启动成功.
**/
import java.util.Random; import java.util.concurrent.Callable; import java.util.concurrent.CompletionService; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutionException; import java.util.concurrent.ExecutorCompletionService; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; /** * CountDownLatch 模拟 运动会长跑 ,裁判 发令 --- 运动员开始努力奔跑 ---- 裁判收集结果 * 1个裁判 和 3个运动员 */ public class CountDownLatchTest1 { public static void main(String[] args) { ExecutorService executor = Executors.newCachedThreadPool(); final CountDownLatch referee = new CountDownLatch(1); // final CountDownLatch athletes = new CountDownLatch(3); // CompletionService<String> completionService =new ExecutorCompletionService<String>(executor); final Lock lock=new ReentrantLock(); //创建要 运行的任务 长跑 Callable<String> callable=new Callable<String>() { @Override public String call(){ try { System.out.println("运动员"+Thread.currentThread().getName()+"等待裁判发令"); referee.await(); System.out.println("运动员"+Thread.currentThread().getName()+"收到裁判发令,已经出发"); lock.lock(); //模拟长跑任务 long stime=System.currentTimeMillis(); String thread_name = Thread.currentThread().getName(); for (int i = 0; i < thread_name.length(); i++) { System.out.print(thread_name.charAt(i)); Thread.sleep(new Random().nextInt(10)*100); } System.out.println(); System.out.println("运动员"+Thread.currentThread().getName()+"已经跑完"); //跑完了 athletes.countDown(); return "运动员"+Thread.currentThread().getName()+"花的时间为:"+(System.currentTimeMillis()-stime); } catch (InterruptedException e) { e.printStackTrace(); }finally{ //lock.unlock(); } return "运动员比赛出现失误"; } }; for (int i = 0; i < 3; i++) { completionService.submit(callable); } try { System.out.println("裁判"+Thread.currentThread().getName()+"即将发布命令"); Thread.sleep((long)Math.random()*20000); referee.countDown(); System.out.println("裁判"+Thread.currentThread().getName()+"已经发布命令,等待结果"); athletes.await(); System.out.println("裁判"+Thread.currentThread().getName()+"收到了结果如下:-----------------"); for (int i = 0; i < 3; i++) { try { System.out.println(completionService.take().get()); } catch (ExecutionException e) { e.printStackTrace(); } } } catch (InterruptedException e) { e.printStackTrace(); } executor.shutdown(); } }
import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; /** * @description 三个领导 审批 --一个采购员去采购 */ public class CountDownLatchTest2 { public static void main(String[] args) { ExecutorService service = Executors.newCachedThreadPool(); final CountDownLatch leader = new CountDownLatch(3); //三个领导 final CountDownLatch buyer = new CountDownLatch(1); //只有一个裁判 final Lock lock=new ReentrantLock(); Runnable runnable = new Runnable() { @Override public void run() { try{ System.out.println("领导"+Thread.currentThread().getName()+"开始进行了审批"); lock.lock(); String thread_name = Thread.currentThread().getName(); for (int i = 0; i < thread_name.length(); i++) { System.out.print(thread_name.charAt(i)); } System.out.println(); System.out.println("领导"+Thread.currentThread().getName()+"已经审批完了"); leader.countDown(); //一个已经结束 if(leader.getCount()==0){ buyer.countDown(); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ lock.unlock(); } } }; for (int i = 0; i < 3; i++) { service.execute(runnable); } try { System.out.println("采购员"+Thread.currentThread().getName()+"在等待,领导审批"); leader.await(); System.out.println("采购员"+Thread.currentThread().getName()+"的单子,已经通过了所有领导审批"); System.out.println("采购员去采购了...."); } catch (InterruptedException e) { e.printStackTrace(); } service.shutdown(); } }
/** * CountDownLatch 是一个倒计数的锁存器,当计数减至0时触发特定的事件。利用这种特性,可以让主线程 等待 子线程的结束运行 */ public class CountDownLatchTest { /** * @param args */ 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) { // TODO: handle exception } } }; 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()+"已经发布命令,正在等待结果..."); cdAnswer.await(); System.out.println("线程"+Thread.currentThread().getName()+"已经收到所有响应结果"); } catch (Exception e) { // TODO: handle exception } } }