用synchronized实现简单例子

package com.thread;public class SynWindow implements Runnable {	Object object;	Object object2;	String name;	static int count=10;	public SynWindow(String name,Object object,Object object2) {		// TODO Auto-generated constructor stub		this.object = object;		this.object2 = object2;		this.name = name;	}	public void serviceWindow() {				while(count>0){				synchronized (object) {					synchronized (object2) {						System.out.PRintln(getName()+"服务"+count+"号客户");						count-=1;						object2.notify();					}					try {						object.wait();					} catch (Exception e) {						// TODO: handle exception					}				}		}			}	@Override	public void run() {		// TODO Auto-generated method stub		serviceWindow();	}		public String getName() {		return name;	}	public void setName(String name) {		this.name = name;	}	public static void main(String[] args) {		// TODO Auto-generated method stub		Object a = new Object();		Object b = new Object();		Object c = new Object();		SynWindow s1 = new SynWindow("窗口一", a, b);		SynWindow s2 = new SynWindow("窗口二", b, c);		SynWindow s3 = new SynWindow("窗口三", c, a);		Thread t1 = new Thread(s1);		Thread t2 = new Thread(s2);		Thread t3 = new Thread(s3);		t1.start();		try {			t1.sleep(100);		} catch (Exception e) {			// TODO: handle exception		}		t2.start();		t3.start();	}}一段synchronized的代码被一个线程执行之前，他要先拿到执行这段代码的权限，在java里边就是拿到某个同步对象的锁（一个对象只有一把锁）； 如果这个时候同步对象的锁被其他线程拿走了，他（这个线程）就只能等了（线程阻塞在锁池等待队列中）。 取到锁后，他就开始执行同步代码(被synchronized修饰的代码）；线程执行完同步代码后马上就把锁还给同步对象，其他在锁池中等待的某个线程就可以拿到锁执行同步代码了。这样就保证了同步代码在统一时刻只有一个线程在执行。