Java 多线程-生产者、消费者

一、整体代码

        ThreadDemo.java

public  class ThreadDemo { 
        public static void main(String[] args) { 
                Godown godown = new Godown(0); 
                Consumer c1 = new Consumer(50, godown); 
                Consumer c2 = new Consumer(20, godown); 
                Consumer c3 = new Consumer(30, godown); 
                Producer p1 = new Producer(10, godown); 
                Producer p2 = new Producer(10, godown); 
                Producer p3 = new Producer(10, godown); 
                Producer p4 = new Producer(10, godown); 
                Producer p5 = new Producer(10, godown); 
                Producer p6 = new Producer(10, godown); 
                Producer p7 = new Producer(80, godown); 

                c1.start(); 
                c2.start(); 
                c3.start(); 
                p1.start(); 
                p2.start(); 
                p3.start(); 
                p4.start(); 
                p5.start(); 
                p6.start(); 
                p7.start(); 
        } 
} 

/** 
* 仓库 
*/ 
class Godown { 
        public static final int max_size = 100; //最大库存量 
        public int curnum;     //当前库存量 

        Godown() { 
        } 

        Godown(int curnum) { 
                this.curnum = curnum; 
        } 

        /** 
         * 生产指定数量的产品 
         * 
         * @param neednum 
         */ 
        public synchronized void produce(int neednum) { 
                //测试是否需要生产 
                while (neednum + curnum > max_size) { 
                        System.out.println("要生产的产品数量" + neednum + "超过剩余库存量" + (max_size - curnum) + "，暂时不能执行生产任务!"); 
                        try { 
                                //当前的生产线程等待 
                                wait(); 
                        } catch (InterruptedException e) { 
                                e.printStackTrace(); 
                        } 
                } 
                //满足生产条件，则进行生产，这里简单的更改当前库存量 
                curnum += neednum; 
                System.out.println("已经生产了" + neednum + "个产品，现仓储量为" + curnum); 
                //唤醒在此对象监视器上等待的所有线程 
                notifyAll(); 
        } 

        /** 
         * 消费指定数量的产品 
         * 
         * @param neednum 
         */ 
        public synchronized void consume(int neednum) { 
                //测试是否可消费 
                while (curnum < neednum) { 
                        try { 
                                //当前的生产线程等待 
                                wait(); 
                        } catch (InterruptedException e) { 
                                e.printStackTrace(); 
                        } 
                } 
                //满足消费条件，则进行消费，这里简单的更改当前库存量 
                curnum -= neednum; 
                System.out.println("已经消费了" + neednum + "个产品，现仓储量为" + curnum); 
                //唤醒在此对象监视器上等待的所有线程 
                notifyAll(); 
        } 
} 

/** 
* 生产者 
*/ 
class Producer extends Thread { 
        private int neednum;                //生产产品的数量 
        private Godown godown;            //仓库 

        Producer(int neednum, Godown godown) { 
                this.neednum = neednum; 
                this.godown = godown; 
        } 

        public void run() { 
                //生产指定数量的产品 
                godown.produce(neednum); 
        } 
} 

/** 
* 消费者 
*/ 
class Consumer extends Thread { 
        private int neednum;                //生产产品的数量 
        private Godown godown;            //仓库 

        Consumer(int neednum, Godown godown) { 
                this.neednum = neednum; 
                this.godown = godown; 
        } 

        public void run() { 
                //消费指定数量的产品 
                godown.consume(neednum); 
        } 
}

二、解释