1 package multithread4;
 2 
 3 /*
 4  * 生产者，消费者。
 5  * 
 6  * 多生产者，多消费者的问题。
 7  * 
 8  * if判断标记，只有一次，会导致不该运行的线程运行了。出现了数据错误的情况。
 9  * while判断标记，解决了线程获取执行权后，是否要运行！
10  * 
11  * notify：只能唤醒一个线程，如果本方唤醒了本方，没有意义。而且while判断标记+notify会产生死锁
12  * notifyAll解决了，本方线程一定会唤醒对方线程
13  * 
14  * 死锁 四个线程都等待没有被唤醒也是一种情况，悬挂
15  */
16 
17 class Resource2{
18     private String name;
19     private int count = 1;
20     private boolean flag = false;
21     public synchronized void set(String name) {
22         
23 /*if*/ while (flag) {
24             try {
25                 this.wait();
26             } catch (InterruptedException e) {
27                 
28             }
29         }
30         this.name = name + count;
31         count++;
32         System.out.println(Thread.currentThread().getName()+"..生产者.."+this.name);
33         flag = true;
34 //        notify();
35         notifyAll();
36     }
37     public synchronized void out() {
38 /*if*/ while (!flag) {
39             try {
40                 this.wait();
41             } catch (InterruptedException e) {
42                 
43             }
44         }
45         System.out.println(Thread.currentThread().getName()+"..消费者......"+this.name);
46         flag = false;
47 //        notify();
48         notifyAll();//为了解决死锁 将其余三个都唤醒
49     }
50 }
51 
52 class Producer implements Runnable{
53     private Resource2 r;
54     public Producer(Resource2 r) {
55         this.r = r;
56     }
57     public void run() {
58         while(true) {
59             r.set("烤鸭");
60         }
61     }
62 }
63 class Consumer implements Runnable{
64     private Resource2 r;
65     public Consumer(Resource2 r) {
66         this.r = r;
67     }
68     public void run() {
69         while(true) {
70             r.out();
71         }
72     }
73 }
74 public class ProducerConsumerDemo {
75 
76     public static void main(String[] args) {
77         
78         Resource2 r = new Resource2();
79         Producer pro = new Producer(r);
80         Consumer con = new Consumer(r);
81         
82         Thread t0 = new Thread(pro);
83         Thread t1 = new Thread(pro);
84         Thread t2 = new Thread(con);
85         Thread t3 = new Thread(con);
86         
87         t0.start();
88         t1.start();
89         t2.start();
90         t3.start();
91     }
92 
93 }

ProducerConsumerDemo