Java中的生产者消费者问题（多线程间同步通信）

JDK1.5之前的版本

<strong><span style="font-size:18px;">class ProducerConsumerDemo {public static void main(String[] args) {Resource r = new Resource();Producer pro = new Producer(r);Consumer con = new Consumer(r);Thread t1 = new Thread(pro);Thread t2 = new Thread(pro);Thread t3 = new Thread(con);Thread t4 = new Thread(con);t1.start();t2.start();t3.start();t4.start();}}/*对于多个生产者和消费者。为什么要定义while判断标记。原因：让被唤醒的线程再一次判断标记。为什么定义notifyAll，因为需要唤醒对方线程。因为只用notify，容易出现只唤醒本方线程的情况。导致程序中的所有线程都等待。*/class Resource{private String name;private int count = 1;private boolean flag = false;//  t1    t2public synchronized void set(String name){while(flag)try{this.wait();}catch(Exception e){}//t1(放弃资格)  t2(获取资格)this.name = name+"--"+count++;System.out.println(Thread.currentThread().getName()+"...生产者.."+this.name);flag = true;this.notifyAll();}//  t3   t4  public synchronized void out(){while(!flag)try{wait();}catch(Exception e){}//t3(放弃资格) t4(放弃资格)System.out.println(Thread.currentThread().getName()+"...消费者........."+this.name);flag = false;this.notifyAll();}}class Producer implements Runnable{private Resource res;Producer(Resource res){this.res = res;}public void run(){while(true){res.set("+商品+");}}}class Consumer implements Runnable{private Resource res;Consumer(Resource res){this.res = res;}public void run(){while(true){res.out();}}}</span></strong>

JDK1.5以后版本

<strong><span style="font-size:18px;">import java.util.concurrent.locks.*;class ProducerConsumerDemo2 {public static void main(String[] args) {Resource r = new Resource();Producer pro = new Producer(r);Consumer con = new Consumer(r);Thread t1 = new Thread(pro);Thread t2 = new Thread(pro);Thread t3 = new Thread(con);Thread t4 = new Thread(con);t1.start();t2.start();t3.start();t4.start();}}/*JDK1.5 中提供了多线程升级解决方案。将同步Synchronized替换成现实Lock操作。将Object中的wait，notify notifyAll，替换了Condition对象。该对象可以Lock锁 进行获取。该示例中，实现了本方只唤醒对方操作。Lock:替代了Synchronizedlock unlocknewCondition()Condition：替代了Object wait notify notifyAllawait();signal();signalAll();*/class Resource{private String name;private int count = 1;private boolean flag = false;//  t1    t2private Lock lock = new ReentrantLock();private Condition condition_pro = lock.newCondition();private Condition condition_con = lock.newCondition();public  void set(String name)throws InterruptedException{lock.lock();try{while(flag)condition_pro.await();//t1,t2this.name = name+"--"+count++;System.out.println(Thread.currentThread().getName()+"...生产者.."+this.name);flag = true;condition_con.signal();}finally{lock.unlock();//释放锁的动作一定要执行。}}//  t3   t4  public  void out()throws InterruptedException{lock.lock();try{while(!flag)condition_con.await();System.out.println(Thread.currentThread().getName()+"...消费者........."+this.name);flag = false;condition_pro.signal();}finally{lock.unlock();}}}class Producer implements Runnable{private Resource res;Producer(Resource res){this.res = res;}public void run(){while(true){try{res.set("+商品+");}catch (InterruptedException e){}}}}class Consumer implements Runnable{private Resource res;Consumer(Resource res){this.res = res;}public void run(){while(true){try{res.out();}catch (InterruptedException e){}}}}</span></strong>