java并发：初探消费者和生产者模式

消费者和生产者模式

用继承Thread方式，用wait和notifyAll方法实现。

消费者和生产者模式的特点

1. 什么时候生产：仓库没有满的时候，生产者这可以生产，消费者也可以消费，仓库满的时候停止生产
2. 什么时候消费: 仓库有货的时候消费，没有货不能消费
3. 通知生产：消费者发现没有货，消费者通知生产者生产
4. 通知消费：生产者生产出产品后，通知消费者消费

代码实现

package com.java.javabase.thread.base;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;

/*
    1. 什么时候生产：仓库没有满的时候，生产者这可以生产，消费者也可以消费，仓库满的时候停止生产
    2. 什么时候消费: 仓库有货的时候消费，没有货不能消费
    3. 通知生产：消费者发现没有货，消费者通知生产者生产
    4. 通知消费：生产者生产出产品后，通知消费者消费
 */
@Data
@Slf4j
@AllArgsConstructor
@RequiredArgsConstructor
class Dept {
    private int capacity;
    private int size;

    /*
    @param val 是生产的产品数量
     */
    public synchronized void produce(int val) {
        //
        int remainder = val;
        while (remainder > 0) {
            if (size >= capacity) {
                try {
                    //仓库满了，等待不在执行生产
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            int incre = (size + remainder) > capacity ? capacity - size : remainder;
            size += incre;
            remainder -= incre;
            log.info("produce {} .depet increment {}, remainder {} ,current size is {}",
                    val,incre, remainder, size);
            //结束生产，通知消费或者生产
            notifyAll();
        }

    }

        public synchronized void custom(int val) {
            int remainder = val;
            while(remainder>0){
                if(size<=0){
                    try {
                        //仓库无货，等待不在消费
                        wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                int descre =(size<remainder)?size:remainder;
                size -=descre;
                remainder -=descre;
                log.info("custom {}. depet descrement {}, remainder {} ,current size is {}",
                        val,descre, remainder, size);
                //结束消费，通知消费或者生产
                notifyAll();
            }

    }
}

@AllArgsConstructor
class Producer {
    private Dept dept;

    public void produce(final int val) {
        new Thread() {
            @Override
            public void run() {
                dept.produce(val);
            }
        }.start();
    }

}

@AllArgsConstructor
class Custom {
    private Dept dept;

    public void custom(final int val) {
        new Thread() {
            @Override
            public void run() {
                dept.custom(val);
            }
        }.start();
    }

}

public class DemoProCustomTest {
    public static void main(String[] args) {
        Dept dept =new Dept(100,0);
        Producer producer =new Producer(dept);
        Custom custom =new Custom(dept);
        producer.produce(100);
        producer.produce(190);
        custom.custom(150);
        custom.custom(80);

    }
}

日志结果输出

因为多线程，所以下面的结果只是其中之一的可能性

2019-07-31 19:10:13,297   [Thread-0] INFO  Dept  - produce 100 .depet increment 100, remainder 0 ,current size is 100
2019-07-31 19:10:13,299   [Thread-3] INFO  Dept  - custom 80. depet descrement 80, remainder 0 ,current size is 20
2019-07-31 19:10:13,299   [Thread-2] INFO  Dept  - custom 150. depet descrement 20, remainder 130 ,current size is 0
2019-07-31 19:10:13,300   [Thread-1] INFO  Dept  - produce 190 .depet increment 100, remainder 90 ,current size is 100
2019-07-31 19:10:13,300   [Thread-2] INFO  Dept  - custom 150. depet descrement 100, remainder 30 ,current size is 0
2019-07-31 19:10:13,300   [Thread-1] INFO  Dept  - produce 190 .depet increment 90, remainder 0 ,current size is 90
2019-07-31 19:10:13,300   [Thread-2] INFO  Dept  - custom 150. depet descrement 30, remainder 0 ,current size is 60