经典多线程Java实例 生产者与消费者

    生产者-消费者问题是一个经典的进程同步问题，该问题最早由Dijkstra提出，用以演示他提出的信号量机制。在同一个进程地址空间内执行的两个线程。生产者线程生产物品，然后将物品放置在一个空缓冲区中供消费者线程消费。消费者线程从缓冲区中获得物品，然后释放缓冲区。当生产者线程生产物品时，如果没有空缓冲区可用，那么生产者线程必须等待消费者线程释放出一个空缓冲区。当消费者线程消费物品时，如果没有满的缓冲区，那么消费者线程将被阻塞，直到新的物品被生产出来。

代码如下:

Producer.java 生产者

package factory; class Producer extends Thread {     private Factory sharedLocation;     public Producer( Factory shared) {         super ( "Producer" ) ;         sharedLocation = shared;     }     public void run ( ) {         for ( int count = 1; count < = 10; count + + ) {             try {                 Thread . sleep ( ( int ) ( Math . random ( ) * 2000) ) ;                 sharedLocation. set ( count ) ;             } catch ( InterruptedException e) {                 e. printStackTrace ( ) ;             }         }         System . out. println ( getName ( ) + " 生产结束" ) ;     } }

Consumer.java 消费者

package factory; public class Consumer extends Thread {     private Factory sharedLocation;     public Consumer( Factory shared) {         super ( "Consumer" ) ;         sharedLocation = shared;     }     public void run ( ) {         int sum = 0;         for ( int count = 1; count < = 10; count + + ) {             try {                 Thread . sleep ( ( int ) ( Math . random ( ) * 3000) ) ;                 //消费商品                 sum + = sharedLocation. get ( ) ;             } catch ( InterruptedException e) {                 e. printStackTrace ( ) ;             }         }         System . out. println ( getName ( ) + " 消费总数 " + sum + " 消费结束" ) ;     } }

Factory.java 工厂接口

package factory; public interface Factory {     public void set ( int value ) ;     public int get ( ) ; }

FactorySynchronizedImpl.java 工厂实现

package factory; /**  * 注意get set两个方法使用同一把锁  */ public class FactorySynchronizedImpl implements Factory {     private int item = - 1;     private int sign = 0; // >0是是可以买 ==0是不能卖     private static final int maxSize = 3; // 最大库存     public synchronized void set ( int value ) {         String name = Thread . currentThread ( ) . getName ( ) ;         while ( sign > = maxSize) {             try {                 displayState( "产品 " + name + " 库存已满!等待..." ) ;                 wait ( ) ;             } catch ( InterruptedException e) {                 e. printStackTrace ( ) ;             }         }         item = value ;         + + sign ;         displayState( name + " 生产 " + item ) ;         // 唤醒同锁线程         notify ( ) ;     }     public synchronized int get ( ) {         String name = Thread . currentThread ( ) . getName ( ) ;         while ( sign < = 0) {             try {                 displayState( "无产品 " + name + " 等待" ) ;                 wait ( ) ;             } catch ( InterruptedException e) {                 e. printStackTrace ( ) ;             }         }         - - sign ;         displayState( name + " 买 " + item ) ;         // 唤醒同锁线程         notify ( ) ;         return item ;     }     public void displayState( String operation ) {         System . out. println ( "操作序号:" + item + "/t/t库存:" + sign + "/t" + operation ) ;     } }

Test.java 运行类

package factory; public class Test {     public static void main( String args[ ] ) {         FactorySynchronizedImpl factory = new FactorySynchronizedImpl( ) ;         System . out. println ( ) ;         factory. displayState( "初始化" ) ;         Producer p = new Producer( factory) ;         Consumer c = new Consumer( factory) ;         p. start ( ) ;         c. start ( ) ;     } }

    希望大家有所收获!