Java 生产者/消费者问题实例详解

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：

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。

以下实例演示了如何通过线程解决生产者/消费者问题：

public class ProducerConsumerTest {  public static void main(String[] args) {   CubbyHole c = new CubbyHole();   Producer p1 = new Producer(c, 1);   Consumer c1 = new Consumer(c, 1);   p1.start();    c1.start();  }}class CubbyHole {  private int contents;  private boolean available = false;  public synchronized int get() {   while (available == false) {     try {      wait();     }     catch (InterruptedException e) {     }   }   available = false;   notifyAll();   return contents;  }  public synchronized void put(int value) {   while (available == true) {     try {      wait();     }     catch (InterruptedException e) {      }    }   contents = value;   available = true;   notifyAll();  }}class Consumer extends Thread {  private CubbyHole cubbyhole;  private int number;  public Consumer(CubbyHole c, int number) {   cubbyhole = c;   this.number = number;  }  public void run() {   int value = 0;     for (int i = 0; i < 10; i++) {      value = cubbyhole.get();      System.out.println("消费者 #" + this.number+ " Got: " + value);     }  }}class Producer extends Thread {  private CubbyHole cubbyhole;  private int number;  public Producer(CubbyHole c, int number) {   cubbyhole = c;   this.number = number;  }  public void run() {   for (int i = 0; i < 10; i++) {     cubbyhole.put(i);     System.out.println("生产者 #" + this.number + " put: " + i);     try {      sleep((int)(Math.random() * 100));     } catch (InterruptedException e) { }   }  }}