java多线程 关于synchronized wait notify CountDownLatch CyclicBarrier Semaphore

package com.my.JavaThread;import java.util.Random;import java.util.concurrent.BrokenBarrierException;import java.util.concurrent.Callable;import java.util.concurrent.CountDownLatch;import java.util.concurrent.CyclicBarrier;import java.util.concurrent.ExecutionException;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.FutureTask;import java.util.concurrent.Semaphore;public class CountDownTest {private static void runDAfterABC() {int worker = 3;final CountDownLatch countDownLatch = new CountDownLatch(worker);new Thread(new Runnable() {@Overridepublic void run() {System.out.println("D is waiting for other three threads");try {countDownLatch.await();System.out.println("All done, D starts working");} catch (InterruptedException e) {e.printStackTrace();}}}).start();for (char threadName = 'A'; threadName <= 'C'; threadName++) {final String tN = String.valueOf(threadName);new Thread(new Runnable() {@Overridepublic void run() {System.out.println(tN + "is working");try {Thread.sleep(100);} catch (Exception e) {e.printStackTrace();}System.out.println(tN + "finished");countDownLatch.countDown();}}).start();}}private static void demo3() {final Object lock = new Object();Thread B = new Thread(new Runnable() {@Overridepublic void run() {synchronized (lock) {System.out.println("B 1");System.out.println("B 2");System.out.println("B 3");lock.notify();}}});Thread A = new Thread(new Runnable() {@Overridepublic void run() {synchronized (lock) {System.out.println("A 1");try {lock.wait();} catch (InterruptedException e) {e.printStackTrace();}System.out.println("A 2");System.out.println("A 3");}}});A.start();B.start();}private static void runABCWhenAllReady() {int runner = 3;final CyclicBarrier cyclicBarrier = new CyclicBarrier(runner);final Random random = new Random();for (char runnerName = 'A'; runnerName <= 'C'; runnerName++) {final String rN = String.valueOf(runnerName);new Thread(new Runnable() {@Overridepublic void run() {long prepareTime = random.nextInt(10000) + 100;System.out.println(rN + "is preparing for time:" + prepareTime);try {Thread.sleep(prepareTime);} catch (Exception e) {e.printStackTrace();}try {System.out.println(rN + "is prepared, waiting for others");cyclicBarrier.await(); // 当前运动员准备完毕，等待别人准备好} catch (InterruptedException e) {e.printStackTrace();} catch (BrokenBarrierException e) {e.printStackTrace();}System.out.println(rN + "starts running"); // 所有运动员都准备好了，一起开始跑}}).start();}}private static void doTaskWithResultInWorker() {    Callable<Integer> callable = new Callable<Integer>() {        @Override        public Integer call() throws Exception {            System.out.println("Task starts");            Thread.sleep(1000);            int result = 0;            for (int i=0; i<=101; i++) {                result += i;            }            System.out.println("Task finished and return result");            return result;        }    };    FutureTask<Integer> futureTask = new FutureTask<>(callable);    new Thread(futureTask).start();    try {        System.out.println("Before futureTask.get()");        System.out.println("Result:" + futureTask.get());        System.out.println("After futureTask.get()");    } catch (InterruptedException e) {        e.printStackTrace();    } catch (ExecutionException e) {        e.printStackTrace();    }}public static void semaphoretest() {    //采用新特性来启动和管理线程——内部使用线程池    ExecutorService exec = Executors.newCachedThreadPool();    //只允许2个线程同时访问    final Semaphore semp = new Semaphore(1);    //模拟5个客户端访问    Object lock = new Object();        for (int index = 0; index < 5; index++){    synchronized (lock) {    final int num = index;        Runnable run = new Runnable() {            public void run() {                try {                    //获取许可                    semp.acquire();                    System.out.println("线程" +                         Thread.currentThread().getName() + "获得许可："  + num);                    //模拟耗时的任务                    for (int i = 0; i < 999999; i++) ;                    //释放许可                    semp.release();                    System.out.println("线程" +                         Thread.currentThread().getName() + "释放许可："  + num);                    System.out.println("当前允许进入的任务个数：" +                        semp.availablePermits());                }catch(InterruptedException e){                    e.printStackTrace();                }            }        };        exec.execute(run);        lock.notify();    }    }    //关闭线程池    exec.shutdown();    }public static void main(String[] args) {//CountDownTest.runDAfterABC();//System.out.println("-------");CountDownTest.demo3();//CountDownTest.runABCWhenAllReady();//CountDownTest.doTaskWithResultInWorker();//CountDownTest.semaphoretest();}}

synchronized wait notify CountDownLatch CyclicBarrier  Semaphore