生产者消费者 ProducerConsumer

生产者消费者是常见的同步问题。一个队列，头部生产数据，尾部消费数据，队列的长度为固定值。当生产的速度大于消费的速度时，队列逐渐会填满，这时就会阻塞住。当尾部消费了数据之后，生产者就可以继续生产了。

生产者

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package com.example;   import java.util.List;   public class Producer {       private List<String> list;       public Producer(List<String> list){         this.list = list;     }       public void produce(String str){         synchronized (list){             if(list.size() >= ProducerConsumer.LIST_SIZE){                 try {                     list.wait();                 } catch (InterruptedException e) {                     e.printStackTrace();                 }             }             list.add(0, str);             System.out.println("produce item:"+str);         }     } }

消费者

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package com.example;   import java.util.List;   public class Producer {       private List<String> list;       public Producer(List<String> list){         this.list = list;     }       public void produce(String str){         synchronized (list){             if(list.size() >= ProducerConsumer.LIST_SIZE){                 try {                     list.wait();                 } catch (InterruptedException e) {                     e.printStackTrace();                 }             }             list.add(0, str);             System.out.println("produce item:"+str);         }     } }

测试类

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package com.example;   import java.util.ArrayList; import java.util.List;   public class ProducerConsumer {       public static int LIST_SIZE = 3;       public static void main(String[] args){         producerConsumerTest();     }       private static void producerConsumerTest(){         List<String> list = new ArrayList<String>();         final Producer producer = new Producer(list);         final Consumer consumer = new Consumer(list);           new Thread(new Runnable() {             @Override             public void run() {                 int count = 0;                 while(true){                     count++;                     producer.produce("num"+count);                     try {                         Thread.sleep(1000);                     } catch (InterruptedException e) {                         e.printStackTrace();                     }                 }             }         }).start();           new Thread(new Runnable() {             @Override             public void run() {                 while(true){                     int count = 0;                     while(true){                         consumer.consume();                         try {                             Thread.sleep(2500);                         } catch (InterruptedException e) {                             e.printStackTrace();                         }                     }                 }             }         }).start();         }   }

运行结果：

数据超过3个时候就不能生产了，需要等待消费者。