1、Callable
1、可以有返回值
2、可以抛出异常
3、方法不同、run()/call()
future Task
细节：
1、有缓存
2、结果可能需要等待，会阻塞
2、常用的辅助类
2.1 CountDownLatch
package com.add;
import java.util.concurrent.CountDownLatch;
//计数器
public class CountDownLatchDemo {
public static void main(String[] args) throws InterruptedException {
//总数是6
CountDownLatch countDownLatch = new CountDownLatch(6);
for (int i = 0; i < 6; i++) {
new Thread(()->{
System.out.println(Thread.currentThread().getName()+"-->GO OUT");
countDownLatch.countDown();//减法操作
},String.valueOf(i)).start();
}
countDownLatch.await();//判断是否到零，到零执行下一步
System.out.println("Close");
}
}
2.2 CyclicBarrier
package com.add;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
public class CyclicBarrierDemo {
public static void main(String[] args) {
//召唤龙珠
CyclicBarrier cyclicBarrier = new CyclicBarrier(7,()->{
System.out.println("召唤神龙成功");
});
for (int i = 0; i <7 ; i++) {
final int temp = i;
new Thread(()->{
System.out.println(Thread.currentThread().getName()+"收集了"+temp+"个龙珠");
try {
cyclicBarrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
}).start();
}
}
}
2.3 Semaphore
package com.add;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
public class SemaphoreDemo {
public static void main(String[] args) {
Semaphore semaphore = new Semaphore(3);
for (int i = 0; i <6 ; i++) {
new Thread(()->{
//acquire()得到
try {
semaphore.acquire();
System.out.println(Thread.currentThread().getName()+"--->抢到停车位");
TimeUnit.SECONDS.sleep(2);
System.out.println(Thread.currentThread().getName()+"--->离开停车位");
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
semaphore.release();
}
//release()释放
},String.valueOf(i)).start();
}
}
}
原理
semaphore.acquire(); 获得，假设如果已经满了，等待，等待被释放为止
semaphore.release(); 释放，会将当前的信号量释放+1，然后唤醒等待的线程
作用：多个共享资源互斥的使用，并发限流，控制最大的线程数。
