Java wait和notify虚假唤醒原理

package com.test;

/**
 * 资源类
 * @author Huxudong
 * @createTime 2020-04-01 21:57:39
 **/
public class Resource {
  /** 产品数 */
  private int product = 0;

  /** 进货 */
  public synchronized void get() {
    if(product >= 10) {
      System.out.println(Thread.currentThread().getName()+":"+"产品已满!");
      /** 当商品已经满的时候，进货线程挂起 */
      try {
        this.wait();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }

    /** 进货 */
    System.out.println(Thread.currentThread().getName()+":"+ ++product);
    /** 唤醒其他线程 */
    this.notifyAll();
    
  }

  /** 售货 */
  public synchronized void sale() {
    if(product <= 0) {
      System.out.println(Thread.currentThread().getName()+":"+"产品已空");
      try {
        this.wait();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
    /** 售货 */
    System.out.println(Thread.currentThread().getName()+":"+ --product);
    /** 唤醒其他线程 */
    this.notify();
  }
}

package com.test;

import java.util.concurrent.TimeUnit;

/**
 * 线程操作资源类，实现线程与资源类的解耦合
 * @author Huxudong
 * @createTime 2020-04-01 23:13:54
 **/
public class TestPc {
  public static void main(String[] args) {
    Resource resource = new Resource();
    new Thread(()->{
      for (int i = 0; i < 20; i++) {
        try {
          /** 睡眠，便于观察结果 */
          TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        resource.get();
      }
    },"生产者A").start();



    new Thread(()->{
      for (int i = 0; i < 20; i++) {
        resource.sale();
      }

    },"消费者C").start();

    new Thread(()->{
      for (int i = 0; i < 20; i++) {

        resource.get();
      }

    },"生产者B").start();

    new Thread(()->{
      for (int i = 0; i < 20; i++) {
        resource.sale();
      }

    },"消费者D").start();
  }
}