09-利用session完成用户登陆

最新推荐文章于 2024-12-18 22:39:29 发布

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最新推荐文章于 2024-12-18 22:39:29 发布

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原文链接：http://www.cnblogs.com/siashan/p/3916615.html

本文介绍了一个简单的用户登录及注销流程实现方案，包括登录页面的设计、登录验证逻辑的处理、使用session进行用户状态管理以及注销功能的实现。

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/***********************************************login.html*****************************************/

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
   <form action="/day07/LoginServlet" method="post">
       用户名：<input type="text" name="username"><br>
       密码：<input type="password" name="password"><br>
       <input type="submit" value="登录">;
   </form>
</body>
</html>

/*************************************LoginServlet***********************************************/

package session;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

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

public class LoginServlet extends HttpServlet {

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       response.setCharacterEncoding("UTF-8");
       response.setContentType("text/html;charset=UTF-8");
       PrintWriter out = response.getWriter();
       String name = request.getParameter("username");
       String pwd = request.getParameter("password");

       List<User> list = Db.getAll();
       for(User user:list){
           if(user.getName().equals(name) && user.getPassword().equals(pwd)){
               //登录成功就是向session存一个登录标记
               request.getSession().setAttribute("user", user);//值是user对象
               //跳到首页
               response.sendRedirect(request.getContextPath()+"/index.jsp");
               return;
           }
       }


       out.print("用户名密码不正确");

   }


   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       doGet(request, response);
   }

}
class Db{
   private static List list = new ArrayList();
   static{
       list.add(new User("aaa","123"));
       list.add(new User("bbb","123"));
       list.add(new User("ccc","123"));
   }
   public static List getAll(){
       return list;
   }
}
/*****************************************************************index.jsp*******************************************************************8/

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
welcome:${user.name}<a href="/day07/login.html">登录</a><a href="/day07/LogoutServlet">退出登录</a>
</body>
</html>

/***********************************************LogoutServlet*************************************************/

package session;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

//注销用户登录
public class LogoutServlet extends HttpServlet {

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       HttpSession session = request.getSession(false);
       //先判断session是否为空，空就代表没有用户登录，这是就不做处理，继续跳回到首页
       if(session == null){
           response.sendRedirect("/day07/index.jsp");
           return;
       }
       //不为空就摧毁session跳回到首页
       session.removeAttribute("user");
       response.sendRedirect("/day07/index.jsp");
   }


   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       doGet(request, response);
   }

}