在多线程开发中,最经典的一个模型就是生产者消费者模型,他们有一个缓冲区,缓冲区有最大限制,当缓冲区满
的时候,生产者是不能将产品放入到缓冲区里面的,当然,当缓冲区是空的时候,消费者也不能从中拿出来产品,这就
涉及到了在多线程中的条件判断,Java为了实现这些功能,提供了wait和notify方法,他们可以在线程不满足要求的时候
让线程让出来资源等待,当有资源的时候再notify他们让他们继续工作,下面我们用实际的代码来展示如何使用wait和
notify来实现生产者消费者这个经典的模型。
首先是缓冲区的实现,我们使用LinkedList来代替
- package com.bird.concursey.charpet2;
-
- import java.util.Date;
- import java.util.LinkedList;
- import java.util.List;
-
- public class EventStorage {
-
- private int maxSize;
-
- private List<Date> storage;
-
- public EventStorage() {
- maxSize = 10;
- storage = new LinkedList<Date>();
- }
-
- public synchronized void set() {
- while(storage.size() == maxSize) {
- try {
- wait();
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
-
- storage.add(new Date());
- System.out.printf("Set: %d",storage.size());
- notifyAll();
- }
-
- public synchronized void get() {
- while(storage.size() == 0) {
- try {
- wait();
- } catch (InterruptedException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
-
- System.out.printf("Get: %d: %s",storage.size(),((LinkedList<?>)storage).poll());
- notifyAll();
- }
- }
然后就是生产者和消费者
- package com.bird.concursey.charpet2;
-
- public class Producer implements Runnable {
-
- private EventStorage storge;
-
- public Producer(EventStorage storage) {
- this.storge = storage;
- }
-
- @Override
- public void run() {
- for(int i = 0; i < 100; i++) {
- storge.set();
- }
- }
-
- }
- package com.bird.concursey.charpet2;
-
- public class Consumer implements Runnable {
-
- private EventStorage storage;
-
- public Consumer(EventStorage storage) {
- this.storage = storage;
- }
-
- @Override
- public void run() {
- for(int i = 0; i < 100; i++) {
- storage.get();
- }
- }
-
- public static void main(String[] args) {
- EventStorage storage = new EventStorage();
- Producer producer = new Producer(storage);
- Thread thread1 = new Thread(producer);
-
- Consumer consumer = new Consumer(storage);
- Thread thread2 = new Thread(consumer);
-
- thread2.start();
- thread1.start();
- }
- }
可以看到,这里面就是用了wait和notifyall方法实现了生产者消费方法,具体的运行过程大家可以通过阅读代码来体
会,还是很直观的。
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