java jdk5.0生产者消费者升级版

import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;public class Test_Producer_Consumer {public static void main(String[] args) {Resource res = new Resource();Producer pro = new Producer(res);Consumer con = new Consumer(res);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();}}/* * class Resource { private String name; private int count = 1; private boolean * flag = false; *  * public synchronized void set(String name) { while(flag) { try { this.wait(); * } catch (InterruptedException e) { e.printStackTrace(); } } this.name = name * + "..." + count++; System.out.println(Thread.currentThread().getName() + * "...生产了..." + name); flag = true; this.notifyAll(); } *  * public synchronized void out() { while(!flag) { try { this.wait(); } catch * (InterruptedException e) { e.printStackTrace(); } } * System.out.println(Thread.currentThread().getName() + "...消费了.............." * + name); flag = false; this.notifyAll(); } } */class Resource {private String name;private int count = 1;private boolean flag = false;/* * JDK5.0对线程同步问题进行了升级 */private Lock lock = new ReentrantLock();private Condition condition_pro = lock.newCondition();private Condition condition_con = lock.newCondition();public void set(String name) {lock.lock();try {while (flag) {condition_pro.await();}this.name = name + "..." + count++;System.out.println(Thread.currentThread().getName() + "...生产了..."+ name);flag = true;condition_con.signalAll();} catch (InterruptedException e) {e.printStackTrace();} finally { // 不管你await有没有出错，你的锁一定会要释放lock.unlock();}}public void out() {lock.lock();try {while (!flag) {condition_con.await();}System.out.println(Thread.currentThread().getName()+ "...消费了.............." + name);flag = false;condition_pro.signalAll();} catch (InterruptedException e) {e.printStackTrace();} finally { // 不管你await有没有出错，你的锁一定会要释放lock.unlock();}}}class Producer implements Runnable {private Resource res;Producer(Resource res) {this.res = res;}@Overridepublic void run() {while (true) {res.set("商品");}}}class Consumer implements Runnable {private Resource res;Consumer(Resource res) {this.res = res;}@Overridepublic void run() {while (true) {res.out();}}}

JDK5.0对多线程同步进行了升级

将隐式的synchronized替换成了显式的Lock对象

将Object对象中的wait、notify、notifyAll，替换成了Condition对象

因为等待和唤醒是针对锁对象的，所以Condition对象的实例可以通过Lock对象的newCondition()方法拿到

并且升级之后最大的好处是一个锁对象可以对应多个Condition对象，这样在生产者消费者的例子中就可以解决

唤醒的时候把本方唤醒的问题，通过不同的Condition对象，可以选择让哪些Condition对象等待，哪些Condition对象唤醒