package com.pas.session;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;
import javax.servlet.http.HttpSession;public class SessionTest extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {this.doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=gb2312");PrintWriter out = response.getWriter();HttpSession sss = request.getSession();sss.setAttribute("uname", "uname");sss.setAttribute("pas", "pas");// 设置周期时间 秒 默认30分钟/** 一个地方是：tomcat/conf/web.xml <session-config>* <session-timeout>30</session-timeout> </session-config> 对所有的web应用生效。* 第二个地方是：在单个web应用下的web.xml文件下添加或修改ession-config <session-config>* <session-timeout>10</session-timeout> </session-config> 只对本web应用生效* 如果两个配置文件冲突，就以单个web应用的配置为准。*/sss.setMaxInactiveInterval(3600);sss.removeAttribute("uname");//remove后输出null//输出uname=true,pas=pas out.println("uname=" + (sss.getAttribute("uname")==null) + ",pas="+ sss.getAttribute("pas"));//终结所有Session对象sss.invalidate();//用户权限判断HttpSession s=request.getSession(true);if(s.isNew()){out.println("非法登录");}out.flush();out.close();}

//权限检查
private void premSessionCheck(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {HttpSession sessionCheck=request.getSession(true);User u=(User)sessionCheck.getAttribute("User");if(u==null){request.setAttribute("err", "用户名或密码错误！");request.getRequestDispatcher("/LoginServlet").forward(request, response);return;}}}