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有关session的登录注销的一个小例子

2016-08-04 16:45 302 查看

下面是一个session的应用的小例子，是用来注销登录的

登陆界面的代码:

login.html:

[java]
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>login.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    


  </head>

  <body>
    <form action="/day07/LoginServlet" method="post">
          用户名：<input text="text" name="username"><br/>
          密码：  <input text="password" name="password"><br/>
    <input type="submit" value="登陆">
  </body>
</html>

用户的javaBean

User.java:

[java]
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package cn.edu.login;


public class User {
    private String username;
    private String password;

    public User(String username, String password) {
        super();
        this.username = username;
        this.password = password;
    }

    public User(){
        super();
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }


}

处理登录信息的Servlet，如果用户账号密码输入正确，就让用户跳转到欢迎界面，顺

便将用户信息加入到session中。

LoginServlet:

[java]
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package cn.edu.login;


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 {


    public 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 username=request.getParameter("username");
       String password=request.getParameter("password");

       List<User> list=Db.getAll();//这里的Db是我自己写的假数据库，里面有一


些User的账号密码信息，是内部类，在下面有
       for(User user:list){
           if(user.getUsername().equals(username)&&user.getPassword


().equals(password)){
               request.getSession().setAttribute("user", user);//登陆成


功，向session中存入一个登陆标记
               response.sendRedirect("/day07/index.jsp");
               return;
           }
       }

       out.write("用户名或者密码错误！");
    }


    public void doPost(HttpServletRequest request, HttpServletResponse


response)
            throws ServletException, IOException {
        doGet(request,response);
    }


}


//模拟数据库(上面提到的)
class Db{
    private static List<User> list=new ArrayList<User>();
    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;
    }
}

欢迎界面，可以从session中拿出用户姓名信息显示在主页上

index.jsp:

[html]
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<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName


()+":"+request.getServerPort()+path+"/";
%>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'index.jsp' starting page</title>
    <mate http-equiv="content-type" content="text/html;charset=UTF-8">
  </head>

  <body>
     欢迎您！${user.username}
     <br/>
  <a href="/day07/login.html">登录</a>  <a href="/day07/LogoutServlet">退出


登录</a>


  </body>
</html>

//注销时使用的Servlet，将session中加入的用户信息清除
LogoutServlet:

[java]
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package cn.edu.login;


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;
//完成用户注销
public class LogoutServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse


response)
            throws ServletException, IOException {
        HttpSession session=request.getSession(false);
        if(session==null){
            response.sendRedirect("/day07/index.jsp");
            return;
        }

        session.removeAttribute("user");
        response.sendRedirect("/day07/index.jsp");
    }


    public void doPost(HttpServletRequest request, HttpServletResponse


response)
            throws ServletException, IOException {
       doGet(request,response);
    }


}

这样，当用户点击退出登录的时候，session中就没有用户的相应信息，用户再次进入主页或登录页面的时候，就会显示用户没有登录。

转载请注明出处:http://blog.csdn.net/acmman

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