生产者消费者问题

public class Depot {
    
    int capacity ;
    int size;
    public Depot(int capacity){
        this.capacity = capacity;
        this.size = 0;
    }
    
    public synchronized void produce(int val){
        try{
            int left = val;//val可能 > capacity，因此需要多次生产
            while(left > 0){//
                while(size >= capacity){//当库存已满时，生产者需要将自己挂起，并唤醒消费者，让消费者来消费。
                    wait();
                }
                int inc = (size + left) > capacity ? (capacity - size) : left;//每次生产的数量与capacity有关
                size += inc;
                left -= inc;
                System.out.printf("%s produce(%3d) --> left=%3d, inc=%3d, size=%3d
", Thread.currentThread().getName(), val, left, inc, size);
                notifyAll();//唤醒消费者来消费
            }
        }catch(Exception e){
        }
    }
    
    public synchronized void consum(int val){
        try{
            int left = val;
            while(left > 0){
                while(size <= 0){//当库存为0时，消费者将自己挂起，通知生产者生产
                    wait();
                }
                int dec = (size > left) ? left : size;//同上
                size -= dec;
                left -= dec;
                System.out.printf("%s consume(%3d) --> left=%3d, dec=%3d, size=%3d
", Thread.currentThread().getName(), val, left, dec, size);
                notifyAll();
            }
        }catch(Exception e){}
    }
    
}

生产者& 消费者对工厂的访问：

public class ConsumerAndProducer {
    public static void main(String[] args) {
        Depot depot = new Depot(100);
        Producer pro = new Producer(depot);
        Consumer con = new Consumer(depot);
        pro.produce(120);
        pro.produce(150);
        con.consum(110);
        con.consum(120);
    }
}

class Consumer {
    Depot depot;
    public Consumer(Depot depot){
        this.depot = depot;
    }
    public void consum(final int val){
        new Thread(){
            public void run(){
                depot.consum(val);
            }
        }.start();
    }
}
class Producer{
    Depot depot;
    public Producer(Depot depot){
        this.depot = depot;
    }
    public void produce(final int val){
        new Thread(){
            public void run(){
                depot.produce(val);
            }
        }.start();
    }
}

多线程相关