CountDownLatch：让一些线程阻塞直到另一些线程完成一系列操作后才被唤醒
CountDownLatch主要有两个方法，当一个或多个线程调用await()方法时，调用线程会被阻塞。其它线程调用countDown()方法会将计数器减1(调用countDown方法的线程不会阻塞)，当计数器的值变为零时，因调用await方法被阻塞的线程会被唤醒，继续执行。
//这个枚举一定要学会，项目中常用
public enum CountryEnum{ONE(1, "齐"),TWO(2, "楚"),THREE(3, "燕"),FOUR(4, "赵"),FIVE(5, "韩"),SIX(6, "魏");@Getter private Integer retCode;@Getter private String retMessage;countryEnum(Integer retCode, String retMessage){this.retCode = retCode;this.retMessage = retMessage;}public static CountryEnum forEach_CountryEnum(int index){CountryEnum[] myArray = CountryEnum.values();for(CountryEnum element : myArray){if(index == element.getRetCode()){return element;}}return null;}
}public class CountDownLatchDemo{public static void main(String[] args) throws Exception{CountDownLatch counDownLatch = new CountDownLatch(6);for(int i = 1; i <= 6; i++){new Thread(() -> {System.out.println(Thread.currentThread.getName()+"\t 国，被灭");countDownLatch.countDown();},CountryEnum.forEach_CountryEnum(i).getRetMessage()).start();}countDownLatch.await();System.out.println(Thread.currentThread.getName()+"\t 秦帝国，一统华夏");System.out.println(CountryEnum.ONE);System.out.println(CountryEnum.ONE.getRetCode());System.out.println(CountryEnum.ONE.getRetMessage());}public static void closeDoor() throws InterruptedException{CountDownLatch counDownLatch = new CountDownLatch(6);for(int i = 1; i <= 6; i++){new Thread(() -> {System.out.println(Thread.currentThread.getName()+"\t 上完自习，离开教室");countDownLatch.countDown();},String.valueOf(i)).start();}countDownLatch.await();System.out.println(Thread.currentThread.getName()+"\t 班长最后关门走人");}
}CyclicBarrier：字面意思是可循环(Cyclic)使用的屏障(Barrier)。它要做的事情是，让一组线程到达一个屏障(也可以叫同步点)时被阻塞，直到最后一个线程到达屏障时，屏障才会开门，所有被屏障拦截的线程才会继续干活，线程进入屏障通过CyclicBarrier的await()方法
public class CyclicBarrierDemo{public static void main(String[] args){//CyclicBarrier(int parties, Runnable barrierAction)CyclicBarrier cyclicBarrier = new CyclicBarrier(7, () -> {System.out.println("****召唤神龙");});for(int i = 1; i <= 7 ; i++){final int tempInt = i;new Thread(() -> {System.out.println(Thread.currentThread().getName()+"\t 收集到第："+tempInt+"龙珠");try{cyclicBarrier.await();}catch(InterrupttedException e){e.printStackTrace();}},String.valueOf(i)).start();}}
}Semaphone：信号量主要用于两个目的，一个是用于多个共享资源的互斥使用，另一个用于并发线程数的控制
public class SemaphoreDemo{public static void main(String[] args){Semaphore semaphore = new Semaphore(3);//模拟3个停车位for(int i = 1; i <= 6; i++){//模拟6部汽车new Thread(() -> {try{semaphore.acquire();System.out.println(Thread.currentThread().getName()+"\t 抢到车位");try{//暂停一会儿线程TimeUnit.SECONDS.sleep(3);}catch(InterruptedException e){e.printStackTrace();}System.out.println(Thread.currentThread().getName()+"\t 停车3秒后离开车位");}catch(InterrupttedException e){e.printStackTrace();}finally{}},String.valueOf(i)).start();}}
}