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生产者--消费者模式
1、示例:
class Resource{ private String name; private int count = 1; private Boolean flag = false; public synchronized void set(String name){ if(flag) try { this.wait();//this代表调用函数线程 } catch (InterruptedException e) {} this.name = name+"__ " + count++; System.out.println(Thread.currentThread().getName()+ "......生产者" + this.name); flag = true; this.notifyAll(); } public synchronized void show(){ if(!flag) try { this.wait(); } catch (InterruptedException e) { } System.out.println(Thread.currentThread().getName()+"消费者"+ this.name); flag = false; this.notifyAll(); } } //定义生产类Producter,生产商品 class Producter implements Runnable{ private Resource r; Producter(Resource r){ this.r = r; } public void run(){ while(true){ r.set("商品"); } } } //定义消费者类Customer,消费商品 class Customer implements Runnable{ private Resource r; Customer(Resource r){ this.r = r; } public void run(){ while(true){ r.show(); } } }
分析:
原因:让被唤醒的线程再次判断标记
原因: 因为需要唤醒对方线程,如果使用notify容易出现值唤醒本方线程的情况,导致线程中所有线程都处于等待状态
2.JDK5中提供多线程解决方案
示例:
package unit18; import java.util.concurrent.locks.*; class Resources{ private String name; private int count = 1; private Boolean flag = false; private Lock lock = new ReentrantLock();//定义Lock类 private Condition condition_pro = lock.newCondition(); private Condition condition_con = lock.newCondition(); public void set(String name)throws InterruptedException{ lock.lock();//添加锁 try{ while(flag){ condition_pro.wait();//生产者调用线程等待 } this.name = name+"__ " + count++; System.out.println(Thread.currentThread().getName()+ "......生产者" + this.name); flag = true; condition_pro.signal(); //唤醒消费者线程 }catch(Exception e){} finally{ lock.unlock();//解锁 } } public synchronized void show()throws InterruptedException{ lock.lock(); try{ while(!flag){ condition_con.wait(); } System.out.println(Thread.currentThread().getName()+"消费者"+ this.name); flag = false; condition_con.signal();//唤醒生产者线程 }catch(Exception e){} finally{ lock.unlock(); } } } class Producters implements Runnable{ private Resources r; Producters(Resources r){ this.r = r; } public void run(){ while(true){ try { r.set("商品"); } catch (InterruptedException e) { } } } } class Customers implements Runnable{ private Resources r; Customers(Resources r){ this.r = r; } public void run(){ while(true){ try { r.show(); } catch (InterruptedException e) { } } } } public class ProducterCustomerTest2 { public static void main(String[] args) { Resources r = new Resources(); Producters pro = new Producters(r); Customers cus = new Customers(r); Thread t1 = new Thread(pro); // Thread t2 = new Thread(pro); // Thread t3 = new Thread(cus); Thread t2 = new Thread(cus); t1.start(); // t2.start(); // t3.start(); t2.start(); } }
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原文地址:http://www.cnblogs.com/chizhongyue/p/4606074.html