生产者与消费者之实现(wait、notify)

2019-11-10 22:12:01

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经典的多线程问题

生产者消费者模型: 1. 商品 2. 仓库 3. 生产者 4. 消费者整个过程大致为:生产者将生产的商品放到仓库存储,消费者将仓库中的商品取出;其中,当库存为零时,消费者会通知生产进行生产;当库存已满时,生产者通知消费者进行消费.

代码

package com.pc.product;import java.io.Serializable;public class Product implements Serializable { private static int counter = 0; private int no = ++counter; private String name; public Product(String name) { super(); this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "Product [no=" + no + ", name=" + name + "]"; }}

Storage.java

package com.pc.storage;import java.util.ArrayList;import java.util.List;import com.pc.product.Product;public class Storage<E extends Product> { private int capacity = 10; private List<E> productsList; public Storage() { productsList = new ArrayList<E>(capacity); } public Storage(int capacity) { if (capacity <= 0) { this.capacity = capacity; } productsList = new ArrayList<E>(capacity); } public void put(E e) { synchronized (productsList) { if (productsList.size() == capacity) { try { productsList.wait(); } catch (InterruptedException e1) { e1.printStackTrace(); } } else { productsList.add(e); productsList.notifyAll(); } } } public E take() { synchronized (productsList) { if (productsList.size() == 0) { try { productsList.wait(); } catch (InterruptedException e1) { e1.printStackTrace(); } } else { productsList.notifyAll(); return productsList.remove(0); } return null; } }}

Producer.java

package com.pc.producer;import com.pc.product.Product;import com.pc.storage.Storage;public class Producer implements Runnable { private Storage<Product> storage; public Producer(Storage<Product> storage) { this.storage = storage; } @Override public void run() { while (true) { synchronized (storage) { Product p = new Product("Product"); storage.put(p); System.out.println(Thread.currentThread().getName() + "/t生产者: " + p); } try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } }}

Consumer.java

package com.pc.consumer;import com.pc.product.Product;import com.pc.storage.Storage;public class Consumer implements Runnable{ private Storage<Product> storage; public Consumer(Storage<Product> storage) { this.storage = storage; } @Override public void run() { while(true){ Product p = storage.take(); if(p != null){ System.out.println(Thread.currentThread().getName() + "/t消费者: "+p); } try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } }}

Test.java

package com.pc.test;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import com.pc.consumer.Consumer;import com.pc.producer.Producer;import com.pc.product.Product;import com.pc.storage.Storage;public class Test { public static void main(String[] args) { Storage<Product> storage = new Storage<Product>(); Producer producer1 = new Producer(storage); Producer producer2 = new Producer(storage); Consumer consumer1 = new Consumer(storage); Consumer consumer2 = new Consumer(storage); Consumer consumer3 = new Consumer(storage); Consumer consumer4 = new Consumer(storage); ExecutorService executorService = Executors.newCachedThreadPool(); executorService.submit(producer1); executorService.submit(producer2); executorService.submit(consumer1); executorService.submit(consumer2); executorService.submit(consumer3); executorService.submit(consumer4); }}

测试结果:

pool-1-thread-2 生产者: Product [no=1, name=Product]pool-1-thread-4 消费者: Product [no=1, name=Product]pool-1-thread-1 生产者: Product [no=2, name=Product]pool-1-thread-6 消费者: Product [no=2, name=Product]pool-1-thread-2 生产者: Product [no=3, name=Product]pool-1-thread-4 消费者: Product [no=3, name=Product]pool-1-thread-1 生产者: Product [no=4, name=Product]pool-1-thread-6 消费者: Product [no=4, name=Product]pool-1-thread-2 生产者: Product [no=5, name=Product]pool-1-thread-1 生产者: Product [no=6, name=Product]pool-1-thread-4 消费者: Product [no=5, name=Product]pool-1-thread-6 消费者: Product [no=6, name=Product]pool-1-thread-2 生产者: Product [no=7, name=Product]pool-1-thread-1 生产者: Product [no=8, name=Product]pool-1-thread-4 消费者: Product [no=7, name=Product]pool-1-thread-6 消费者: Product [no=8, name=Product]pool-1-thread-1 生产者: Product [no=9, name=Product]pool-1-thread-2 生产者: Product [no=10, name=Product]pool-1-thread-4 消费者: Product [no=9, name=Product]pool-1-thread-6 消费者: Product [no=10, name=Product]pool-1-thread-1 生产者: Product [no=11, name=Product]pool-1-thread-2 生产者: Product [no=12, name=Product]pool-1-thread-4 消费者: Product [no=11, name=Product]pool-1-thread-6 消费者: Product [no=12, name=Product]pool-1-thread-1 生产者: Product [no=13, name=Product]pool-1-thread-5 消费者: Product [no=13, name=Product]pool-1-thread-2 生产者: Product [no=14, name=Product]pool-1-thread-6 消费者: Product [no=14, name=Product]

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