生产者和消费者多线程共享一个仓库（多竞争一）

来源：互联网发布：cnc编程兼职工资怎么算编辑：程序博客网时间：2024/05/29 18:16

package org.java.Thread;
public class MultiThread {
//定义一个仓库的容量
private final int MAX_SIZE = 100;
//定义一个显著仓库的商品的数量
private int current;

//数据仓库的构造方法
//初始化他的现在库存量
public MultiThread(int current){
  this.current = current;
}

//仓库是一个共享资源，所以定义两个方法，存放商品和销售商品

public synchronized void produce(int produceNum){
  //获得生产者的名字
  String name = Thread.currentThread().getName();
  while((current+produceNum)>MAX_SIZE){
   //我会会思考，为什么是一个while循环，而不是一个if()，后来我知道了、
   //如果是if，那么这个线程先被wait，过后，只要一被唤醒notify，那么
   //这个线程就执行完了，而不能达到要求。用while的好处就是，唤醒它
   //让它又去判断一次是不是达到要求，达到跳出这个循环时候，这个线程就到达了要求
   //去完成自己的任务。
   System.out.println("仓库现在的商品量是："+current+","+name+"不能把自己生产的"+produceNum+"个商品放入仓库了,不然就爆仓了");
   try {
    //当没有达到要求，就释放锁，给其他线程去锁定这个一起共享的（单独）对象
    //那么这个线程就这里等待~~，当唤醒的时候，再去判断，符合才去完成它的任务。
    wait();
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
  current += produceNum;
  System.out.println(name+"把自己生产的"+produceNum+"个商品放入仓库中！");
  System.out.println("现在仓库的商品量是："+current);
  //多个线程共享一个对象，这个对象用notifyAll方法来唤醒
  notifyAll();

}

//销售商品
public synchronized void reduce(int reduceNum){
  String name = Thread.currentThread().getName();
  while((current-reduceNum)<0){
   System.out.println("仓库现在的商品量是："+current+","+name+"不能从仓库拿走"+reduceNum+"个商品");
   try {
    wait();
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
  current -= reduceNum;
  System.out.println(name+"从仓库中拿走了"+reduceNum+"个商品！");
  System.out.println("现在仓库的商品量是："+current);
  notifyAll();

}

public static void main(String[] args){
  MultiThread mul = new MultiThread(30);
  Producer p1 = new Producer("p1",10,mul);
  Producer p2 = new Producer("p2",20,mul);
  Producer p3 = new Producer("p3",30,mul);
  Producer p4 = new Producer("p4",40,mul);
  Producer p5 = new Producer("p5",50,mul);
  Consumer c1 = new Consumer("c1",20,mul);
  Consumer c2 = new Consumer("c2",30,mul);
  Consumer c5 = new Consumer("c5",50,mul);
  Consumer c3 = new Consumer("c3",40,mul);
  Consumer c4 = new Consumer("c4",40,mul);

  p1.start();
  p2.start();
  p3.start();
  p4.start();
  p5.start();
  c1.start();
  c2.start();
  c3.start();
  c4.start();
  c5.start();

}
}

class Producer extends Thread{
//生产的商品个数
private int produceNum;
private String name;
private MultiThread multiThread;

public Producer(String name,int produceNum, MultiThread multiThread) {
  super(name);
  this.name = name;
  this.produceNum = produceNum;
  this.multiThread = multiThread;
}

public void run(){
  System.out.println(name+"打算把最近生产的"+produceNum+"个商品放入仓库中");
  multiThread.produce(produceNum);
}
}

class Consumer extends Thread{
//生产的商品个数
private int reduceNum;
private String name;
private MultiThread multiThread;

public Consumer(String name,int reduceNum, MultiThread multiThread) {
  super(name);
  this.name = name;
  this.reduceNum = reduceNum;
  this.multiThread = multiThread;
}

public void run(){
  System.out.println(name+"准备去仓库里拿走"+reduceNum+"个商品");
  multiThread.reduce(reduceNum);
}
}

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