Java多线程 9 多个生产者和消费者

多个生产者和消费者的时候，需要考虑更多情况

package thread;/*对于多个生产者和消费者。为什么要定义while判断标记。原因：让被唤醒的线程再一次判断标记。为什么定义notifyAll，因为需要唤醒对方线程。因为只用notify，容易出现只唤醒本方线程的情况。导致程序中的所有线程都等待。*/public class Thread_6_ProducerConsumerDemo2 {public static void main(String[] args) {Resource r = new Resource();Producer pro = new Producer(r);Consumer con = new Consumer(r);Thread t1 = new Thread(pro);Thread t2 = new Thread(pro);Thread t3 = new Thread(con);Thread t4 = new Thread(con);t1.start();t2.start();t3.start();t4.start();}}class Resource{private String name;private int count = 1;private boolean flag = false;public synchronized void set(String name){//这里的while循环保证了某一方执行notify之后如果不小心被唤醒的是本方，则会被再次等待while(flag)try{this.wait();}catch(Exception e){}this.name = name+"--"+count++;System.out.println(Thread.currentThread().getName()+"...生产者.."+this.name);flag = true;//这里的notifyAll()会唤醒所有生产者和消费者，避免了同一类的所有角色都进入wait状态的风险this.notifyAll();}public synchronized void out(){while(!flag)try{wait();}catch(Exception e){}System.out.println(Thread.currentThread().getName()+"...消费者........."+this.name);flag = false;this.notifyAll();}}class Producer implements Runnable{private Resource res;Producer(Resource res){this.res = res;}public void run(){while(true){res.set("+商品+");}}}class Consumer implements Runnable{private Resource res;Consumer(Resource res){this.res = res;}public void run(){while(true){res.out();}}}