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Java生产者消费者模型 Java实现简易生产者消费者模型过程解析

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一、概述

一共两个线程,一个线程生产产品,一个线程消费产品,使用同步代码块方法,同步两个线程。当产品没有时,通知生产者生产,生产者生产后,通知消费者消费,并等待消费者消费完。

需要注意的是,有可能出现,停止生产产品后,消费者还没未来得及消费生产者生产的最后一个产品,就结束消费,导致最后一个产品没有被消费。

本例使用synchronize以及wait()、notify()实现简易版的线程者消费者模型。

二、测试用例

这里的产品用笔来演示,每只笔都有其编号code

一共有四个类:分别是生产者类,产品类,消费者类,测试类

产品

package test.exception.producer_consumer_model;

/*
假设为产品为笔
 */

public class Production {
  private String type = "";
  private String color = "";
  private long code = 0; // 产品编号
  private boolean isProduced = false; // 是否生产完成 初始状态为未生产状态
  private boolean isContinueProduce = true; // 是否停产该产品

  public void setContinueProduce(boolean continueProduce) {
    isContinueProduce = continueProduce;
  }

  public void setCode(long code) {
    this.code = code;
  }

  public Production(){
  }

  public boolean isContinueProduce() {
    return isContinueProduce;
  }

  public void setType(String type) {
    this.type = type;
  }

  public void setColor(String color) {
    this.color = color;
  }

  public void setProduced(boolean produced) {
    isProduced = produced;
  }

  public boolean isProduced() {
    return isProduced;
  }

  @Override
  public String toString() {
    return color + type + "-" + code;
  }
}

生产者

package test.exception.producer_consumer_model;

public class Producer implements Runnable {
  private final Production pen; // 产品

  public Producer(Production pen) {
    this.pen = pen;
  }

  // 生产
  public void produce() {
    long code = 0;
    while (this.pen.isContinueProduce()) {
      synchronized (this.pen) {
        if (this.pen.isProduced()) {
          try {
            this.pen.wait(); // 等待消费者消费
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
        }
        // 开始生产
        this.pen.setType("铅笔");
        this.pen.setColor("蓝色");
        this.pen.setCode(code++);
        this.pen.setProduced(true);
        System.out.println(this.pen + " is produced");
        this.pen.notify();
      }
    }
    System.out.println("finish producing");
  }
  @Override
  public void run() {
    produce();
  }
}

消费者

package test.exception.producer_consumer_model;

public class Consumer implements Runnable {
  private final Production pen;

  public Consumer(Production pen) {
    this.pen = pen;
  }

  // 持续消费
  public void consumer() {
    while (this.pen.isContinueProduce()) {
      synchronized (this.pen) {
        if (!this.pen.isProduced()) {
          try {
            this.pen.wait(); // 等待生产者生产
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
        }

        System.out.println(this.pen + " is consumed"); // 使用
        this.pen.setProduced(false); // 使用完后更新状态
        this.pen.notify();
      }
    }
    // 确保停止生产后,能够使用最后生产的一支笔
    if (this.pen.isProduced()) {
      System.out.println(this.pen + " is consumed");
    }

    System.out.println("finish using");
  }

  @Override
  public void run() {
    consumer();
  }
}

主线程测试

package test.exception.producer_consumer_model;

public class Demo {
  public static void main(String[] args) throws InterruptedException {
    Production pen = new Production();
    Consumer consumer = new Consumer(pen);
    Producer producer = new Producer(pen);
    new Thread(producer).start(); // 开启生产者线程
    new Thread(consumer).start(); // 开启消费者线程

    Thread.sleep(10000);
    pen.setContinueProduce(false); // 10s后停止生产该类型的笔
  }
}

运行结果

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