使用Session完成登录注销案例

我们可以将对象绑定到HttpSession实例上,并使用setAttribute和getAttribute方法获取对象。

在上一篇《Servlet中HttpSession使用》中,我们了解了什么是HttpSession,如何从会话对象存储和获取数据等。

本文我们将创建一个不使用数据库版本的用户登录和注销应用程序。我们假设密码为yiidian。大致效果是:用户必须先登录才能进入个人中心页面。如果用户已注销,则需要再次登录才能访问个人资料。


为了让大家更加理解Cooke与HttpSession的区别,可以查看Cookie版本的用户登录注销程序:

《使用Cookie完成登录注销案例》


1 编写主页面

index.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>一点教程网-HttpSession完成用户登录和注销</title>
</head>
<body>
<h1>HttpSession完成用户登录和注销</h1>
<a href="login.jsp">登录</a>|
<a href="LogoutServlet">注销</a>|
<a href="ProfileServlet">个人中心</a>
</body>
</html>

2 编写通用链接页面

link.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>一点教程网-HttpSession完成用户登录和注销</title>
</head>
<body>
<a href="login.jsp">登录</a>|
<a href="LogoutServlet">注销</a>|
<a href="ProfileServlet">个人中心</a>
<hr/>
</body>
</html>

3 编写登录页面

login.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>一点教程网-HttpSession完成用户登录和注销</title>
</head>
<body>
<form action="LoginServlet" method="post">
    用户名:<input type="text" name="name"><br>
    密码:<input type="password" name="password"><br>
    <input type="submit" value="登录">
</form>
</body>
</html>

4 编写登录Servlet

LoginServlet:

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/**
 * 一点教程网 - http://www.yiidian.com
 */
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

        response.setContentType("text/html;charset=utf-8");
        PrintWriter out=response.getWriter();
        request.getRequestDispatcher("link.jsp").include(request, response);

        String name=request.getParameter("name");
        String password=request.getParameter("password");

        if(password.equals("yiidian")){
            out.print("欢迎你, "+name);
            HttpSession session=request.getSession();
            session.setAttribute("name",name);
        }
        else{
            out.print("抱歉, 用户名或密码错误!");
            request.getRequestDispatcher("login.jsp").include(request, response);
        }
        out.close();
    }
}

5 编写注销Servlet

LogoutServlet:
 

import javax.servlet.ServletException;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * 一点教程网 - http://www.yiidian.com
 */
public class LogoutServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

        response.setContentType("text/html;charset=utf-8");
        PrintWriter out=response.getWriter();

        request.getRequestDispatcher("link.jsp").include(request, response);

        HttpSession session=request.getSession();
        session.invalidate();

        out.print("你已经成功注销!");

        out.close();
    }
}

6 编写个人中心Servlet

ProfileServlet:
 

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

/**
 * 一点教程网 - http://www.yiidian.com
 */
public class ProfileServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

        response.setContentType("text/html;charset=utf-8");
        PrintWriter out=response.getWriter();
        request.getRequestDispatcher("link.jsp").include(request, response);

        HttpSession session=request.getSession(false);
        if(session!=null && session.getAttribute("name")!=null){
            String name=(String)session.getAttribute("name");

            out.print("你好, "+name+" 欢迎进入个人中心");
        }
        else{
            out.print("请先登录");
            request.getRequestDispatcher("login.jsp").include(request, response);
        }
        out.close();
    }
}

7 配置web.xml

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>LoginServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/LoginServlet</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>ProfileServlet</servlet-name>
        <servlet-class>ProfileServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ProfileServlet</servlet-name>
        <url-pattern>/ProfileServlet</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>LogoutServlet</servlet-name>
        <servlet-class>LogoutServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LogoutServlet</servlet-name>
        <url-pattern>/LogoutServlet</url-pattern>
    </servlet-mapping>


</web-app>

8 运行测试

1)首先访问index.jsp页面,http://localhost:8080/

2)点击“个人中心”,提示如下:

3)点击“登录”,进入登录页面,如下:

4)输入错误的密码,提示如下:

5)输入正确的密码(yiidian),提示如下:

6)点击“个人中心”,如下:

7)点击“注销”,如下:

 

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