Servlet模拟网上售票问题，解决线程的安全问题

package com.lc.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Ticketsell extends HttpServlet {

	public int ticket = 3;//假设只有三张票

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		PrintWriter out = response.getWriter();
		response.setContentType("text/html;charset=gbk");

		//简单点而处理售票问题
		//当一个变量需要多个用户共享，则应该在访问该变量的时候加 同步机制
		//如果一个变量不需要共享则直接在doGet()和doPost()方法中定义即可,这样的话就不存在线程的安全型问题

		synchronized (this) { //解决同步性问题的方法

			if(ticket > 0)
			{
				System.out.println("你买到票了！");
				out.println("你买到票了！");

				//休眠
				try {
					Thread.sleep(10*1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				ticket--;
			}
			else
			{
				System.out.println("你没有买到票！");
				out.println("你没有买到票！");
			}
		}

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);

	}

}

运行结果如下：在不同的游览器中同时访问这个资源  在第三次之后显示 票没有了！