线程间的通信——wait()/notify()

package com.jjyy.thread;/** * 线程间的通讯 *  * 假设有两个线程，A和B。共同拥有一个同步对象，lock。　　    1．首先，线程A通过synchronized(lock) 获得lock同步对象，然后调用lock.wait()函数，放弃lock同步对象，线程A停止运行，进入等待队列。2．线程B通过synchronized(lock) 获得线程A放弃的lock同步对象，做完一定的处理，然后调用 lock.notify() 或者lock.notifyAll()       通知等待队列里面的线程A。3．线程A从等待队列里面出来，进入ready队列，等待调度。4．线程B继续处理，出了synchronized(lock)块之后，放弃lock同步对象。5．线程A获得lock同步对象，继续运行。 * @author jiangyu 2015年9月7日 * A gives up lockB got lockB gives up lockA got lock again and continue to runB has lock ? -- false * */public class Communicate {public static void main(String[] args) {Runnable resource = new ProcessorCore();Thread A = new Thread(resource, "A");Thread B = new Thread(resource, "B");A.start();try {Thread.sleep(500);} catch (InterruptedException e) {e.printStackTrace();}B.start();}}class ProcessorCore implements Runnable {final Object lock = new Object();@Overridepublic void run() {String threadName = Thread.currentThread().getName();if ("A".equals(threadName)) {synchronized (lock) {System.out.println("A gives up lock");try {lock.wait();} catch (InterruptedException e) {e.printStackTrace();}System.out.println("A got lock again and continue to run");}}if ("B".equals(threadName)) {synchronized (lock) {System.out.println("B got lock");lock.notify();System.out.println("B gives up lock");}boolean hasLock = Thread.holdsLock(lock); // 检查B是否拥有lock同步对象。System.out.println("B has lock ? -- " +hasLock); // false.}}}