线程安全问题:

Servlet的service方法,每次被请求是,调用.

这个调用很特殊,是在新的子线程中调用的,当service方法执行完毕,子线程死亡了.

可以简单的理解为:service方法每次执行都是一个新的线程.

package cn.xdl.demo1;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;/*** @author victor* @site https://victorfengming.github.io/* @company XDL* @project xdl_javaweb* @package cn.xdl.demo1* @created 2019-11-15 13:30* @function "线程锁测试"*/
@WebServlet("/s1")
public class Servlet1 extends HttpServlet {// 剩余票数private int count = 10;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 创建线程锁对象,用于作为标记Object ob = new Object();// 这个地方写什么对象都行,别瞎传递就行!synchronized (ob) {if (count > 0) {System.out.println("恭喜你,有票");System.out.println("正在出票");count--;System.out.println("出票完成,剩余票数:" + count);} else {System.out.println("很遗憾,没票了!");}}}
}