java实现生产者消费者问题
2015-10-11 16:32
645 查看
java实现生产者消费者问题
java实现生产者消费者问题
引言生产者和消费者问题是线程模型中的经典问题:生产者和消费者在同一时间段内共用同一个存储空间,如下图所示,生产者向空间里存放数据,而消费者取用数据,如果不加以协调可能会出现以下情况:
生产者消费者图
存储空间已满,而生产者占用着它,消费者等着生产者让出空间从而去除产品,生产者等着消费者消费产品,从而向空间中添加产品。互相等待,从而发生死锁。
JAVA解决线程模型的三种方式
1、wait()和notify()
import java.util.LinkedList; public class ProducerConsumer { private LinkedList<Object> storeHouse = new LinkedList<Object>(); private int MAX = 10; public ProducerConsumer() { } public void start() { new Producer().start(); new Comsumer().start(); } class Producer extends Thread { public void run() { while (true) { synchronized (storeHouse) { try { while (storeHouse.size() == MAX) { System.out.println("storeHouse is full , please wait"); storeHouse.wait(); } Object newOb = new Object(); if (storeHouse.add(newOb)) { System.out.println("Producer put a Object to storeHouse"); Thread.sleep((long) (Math.random() * 3000)); storeHouse.notify(); } } catch (InterruptedException ie) { System.out.println("producer is interrupted!"); } } } } } class Comsumer extends Thread { public void run() { while (true) { synchronized (storeHouse) { try { while (storeHouse.size() == 0) { System.out.println("storeHouse is empty , please wait"); storeHouse.wait(); } storeHouse.removeLast(); System.out.println("Comsumer get a Object from storeHouse"); Thread.sleep((long) (Math.random() * 3000)); storeHouse.notify(); } catch (InterruptedException ie) { System.out.println("Consumer is interrupted"); } } } } } public static void main(String[] args) throws Exception { ProducerConsumer pc = new ProducerConsumer(); pc.start(); } }
2、await()和signal(),即线程锁的方式
package sort; import java.util.LinkedList; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; public class ProducerConsumer { private LinkedList<Object> myList = new LinkedList<Object>(); private int MAX = 10; private final Lock lock = new ReentrantLock(); private final Condition full = lock.newCondition(); private final Condition empty = lock.newCondition(); public ProducerConsumer() { } public void start() { new Producer().start(); new Consumer().start(); } public static void main(String[] args) throws Exception { ProducerConsumer s2 = new ProducerConsumer(); s2.start(); } class Producer extends Thread { public void run() { while (true) { lock.lock(); try { while (myList.size() == MAX) { System.out.println("warning: it's full!"); full.await(); } Object o = new Object(); if (myList.add(o)) { System.out.println("Producer: " + o); empty.signal(); } } catch (InterruptedException ie) { System.out.println("producer is interrupted!"); } finally { lock.unlock(); } } } } class Consumer extends Thread { public void run() { while (true) { lock.lock(); try { while (myList.size() == 0) { System.out.println("warning: it's empty!"); empty.await(); } Object o = myList.removeLast(); System.out.println("Consumer: " + o); full.signal(); } catch (InterruptedException ie) { System.out.println("consumer is interrupted!"); } finally { lock.unlock(); } } } } }
3、阻塞队列的方式
import java.util.concurrent.*; public class ProducerConsumer { // 建立一个阻塞队列 private LinkedBlockingQueue<Object> queue = new LinkedBlockingQueue<Object>(10); public ProducerConsumer() { } public void start() { new Producer().start(); new Consumer().start(); } public static void main(String[] args) throws Exception { ProducerConsumer s3 = new ProducerConsumer(); s3.start(); } class Producer extends Thread { public void run() { while (true) { try { Object o = new Object(); // 取出一个对象 queue.put(o); System.out.println("Producer: " + o); } catch (InterruptedException e) { System.out.println("producer is interrupted!"); } // } } } } class Consumer extends Thread { public void run() { while (true) { try { // 取出一个对象 Object o = queue.take(); System.out.println("Consumer: " + o); } catch (InterruptedException e) { System.out.println("producer is interrupted!"); } // } } } } }
结论
三种方式原理一致,都是对独占空间加锁,阻塞和唤醒线程,第一种方式比较传统,第三种方式最简单,只需存储和取用,线程同步的操作交由LinkedBlockingQueue全权处理。
相关文章推荐
- Java学习——String变量中的双胞胎
- Java I/O
- Java反射、类加载与垃圾回收
- 【转】Java中的深拷贝和浅拷贝
- Java集合框架 泛型
- Java集合框架 List和Set
- Java集合框架
- Java实验二
- 浏览器兼容性解决方案
- 记录使用androidstudio IDE方案替换eclipse+ant
- JavaWeb经典三层框架
- JAVA集合一之集合简介(Collection,List,Set)
- 【SSH三框架】Struts2第一章的基础:第一次写Struts2规划
- keytool 错误 java.io.IOException: incorrect AVA format
- 简单记录围观annotationprocessor,并在eclipse开发自己的ap
- 关于Java函数传参以及参数在函数内部改变的问题——JAVA值传递与引用最浅显的说明!
- StringWriter/PrintWriter在Java输出异常信息中的作用
- javaWeb与MVC
- Java调用SQL Server存储过程
- Eclipse配置Struts2