多生产者多消费者问题及代码

java.多线程

    package 生产者消费者;
    /*
     * 一开始想要做的是单生产者单消费者，没想到后来变成了多生产多消费，改一个东西就够了
     * 
     * 经验教训：
     * 
     * 1.notify()之前必须有另外一个线程正在wait()，否则notify()无效
     * 2.资源类不一定就需要实现接口Runnable，也可以作为实现接口类的输入量
     * 3.逻辑上需要能够过得去，不要写出来就依赖于调试，可以自己头脑运运
     */
    public class Producer1Customer1 {
        static Object lock = new Object();
        public static void main(String[] args) {
            Source ps = new Source();
            Producer p1 = new Producer(ps);
            Producer p2 = new Producer(ps);
            Producer p3 = new Producer(ps);
            Customer c1 = new Customer(ps);
            Customer c2 = new Customer(ps);
            Customer c3 = new Customer(ps);
            new Thread(p1).start();
            new Thread(p2).start();
            new Thread(p3).start();
            new Thread(c1).start();
            new Thread(c2).start();
            new Thread(c3).start();
        }
    }
    //资源类
    class Source{
        int num=100;
        boolean flag = false;
    }
    //生产者
    class Producer implements Runnable{
        Source ps;
        public Producer(Source ps){
            this.ps  = ps;
        }
        @Override
        public void run() {
            while(true){
                synchronized(ps){
                    if(ps.flag){
                        if(ps.num >0){
                            System.out.println(Thread.currentThread().getName()+"生产者"+ps.num);
                            ps.num = ps.num -1;
                            ps.flag = false;
                            ps.notifyAll();
                        }
                        else return;
                    }
                    else{
                        try{
                            ps.wait();
                        }catch(Exception e){
                            e.printStackTrace();
                        }
                    }   
                }
            }
        }
    }
    //消费者
    class Customer implements Runnable{
        Source ps;
        public Customer(Source ps){
            this.ps  = ps;
        }
        @Override
        public void run() {
            while(true){
                synchronized(ps){
                    if(!ps.flag){
                        if(ps.num>0){
                            System.out.println(Thread.currentThread().getName()+"消费者" + ps.num);
                            ps.flag = true;
                            ps.notifyAll();
                        }
                    }
                    else{
                        try{
                            ps.wait();
                        }catch(Exception e){
                            e.printStackTrace();
                        }
                    }   
                }
            }
        }
    }