Session案例-用户登录场景 

package com.loaderman.demo;

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;
/**
 * 用户主页的逻辑
 *
 */
public class IndexServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        PrintWriter writer = response.getWriter();
        String html = "";
        /**
         * 接收request域对象的数据
         */
        /*
        String loginName = (String)request.getAttribute("loginName");
        */
        /**
         * 二、在用户主页，判断session不为空且存在指定的属性才视为登录成功！才能访问资源。
         * 从session域中获取会话数据
         */
        //1.得到session对象
        HttpSession session = request.getSession(false);
        if(session==null){
            //没有登录成功，跳转到登录页面
            response.sendRedirect(request.getContextPath()+"/login.html");
            return;
        }
        //2.取出会话数据
        String loginName = (String)session.getAttribute("loginName");
        if(loginName==null){
            //没有登录成功，跳转到登录页面
            response.sendRedirect(request.getContextPath()+"/login.html");
            return;
        }
        html = "<html><body>欢迎回来，"+loginName+"，<a href='"+request.getContextPath()+"/logout'>安全退出</a></body></html>";
        writer.write(html);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}
package com.loaderman.demo;

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;
/**
 * 处理登录的逻辑
 * @author APPle
 *
 */
public class LoginServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        //1.接收参数
        String userName = request.getParameter("userName");
        String userPwd = request.getParameter("userPwd");
        
        //2.判断逻辑
        if("admin".equals(userName)
                 && "123456".equals(userPwd)){
            //登录成功
            /**
             * 分析：
             *       context域对象：不合适，可能会覆盖数据。
             *    request域对象： 不合适，整个网站必须得使用转发技术来跳转页面
             *    session域对象：合适。
             */
            /*
            request.setAttribute("loginName", userName);
            //request.getRequestDispatcher("/IndexServlet").forward(request, response);
            response.sendRedirect(request.getContextPath()+"/IndexServlet");
            */
            
            /**
             * 一、登录成功后，把用户数据保存session对象中
             */
            //1.创建session对象
            HttpSession session = request.getSession();
            //2.把数据保存到session域中
            session.setAttribute("loginName", userName);
            //3.跳转到用户主页
            response.sendRedirect(request.getContextPath()+"/index");
            
        }else{
            //登录失败
            //请求重定向
            response.sendRedirect(request.getContextPath()+"/fail.html");
        }
    }

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

}
package com.loaderman.demo;

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;
/**
 * 退出逻辑
 *
 */
public class LogoutServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        /**
         * 三、安全退出：
         *         删除掉session对象中指定的loginName属性即可！  
         */
        //1.得到session对象
        HttpSession session = request.getSession(false);
        if(session!=null){
            //2.删除属性
            session.removeAttribute("loginName");
        }
        //2.回来登录页面
        response.sendRedirect(request.getContextPath()+"/login.html");  
    }

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

web.xml配置:

 <servlet>
        <!-- servlet的内部名称，自定义。尽量有意义 -->
        <servlet-name>IndexServlet</servlet-name>
        <!-- servlet的类全名： 包名+简单类名 -->
        <servlet-class>com.loaderman.demo.IndexServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <!-- servlet的内部名称，一定要和上面的内部名称保持一致！！ -->
        <servlet-name>IndexServlet</servlet-name>
        <!-- servlet的映射路径（访问servlet的名称） -->
        <url-pattern>/index</url-pattern>
    </servlet-mapping>
    <servlet>
        <!-- servlet的内部名称，自定义。尽量有意义 -->
        <servlet-name>LoginServlet</servlet-name>
        <!-- servlet的类全名： 包名+简单类名 -->
        <servlet-class>com.loaderman.demo.LoginServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <!-- servlet的内部名称，一定要和上面的内部名称保持一致！！ -->
        <servlet-name>LoginServlet</servlet-name>
        <!-- servlet的映射路径（访问servlet的名称） -->
        <url-pattern>/login</url-pattern>
    </servlet-mapping>
    <servlet>
        <!-- servlet的内部名称，自定义。尽量有意义 -->
        <servlet-name>LogoutServlet</servlet-name>
        <!-- servlet的类全名： 包名+简单类名 -->
        <servlet-class>com.loaderman.demo.LogoutServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <!-- servlet的内部名称，一定要和上面的内部名称保持一致！！ -->
        <servlet-name>LogoutServlet</servlet-name>
        <!-- servlet的映射路径（访问servlet的名称） -->
        <url-pattern>/logout</url-pattern>
    </servlet-mapping>

fail.xml

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>信息提示页面</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">
    
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->

  </head>
  
  <body>
    <font color='red' size='3'>亲， 你的用户名或密码输入有误！请重新输入!</font><br/>
    <a href="/login.html">返回登录页面</a>
  </body>
</html>

login.xml

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>登录页面</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">
    
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->

  </head>
  
  <body>
    <form action="/login" method="post">
        用户名:<input type="text" name="userName"/>
        <br/>
        密码：<input type="text" name="userPwd"/>
        <br/>
        <input type="submit" value="登录"/>
    </form>
  </body>
</html>

ok ,运行服务器,访问index,就可以模拟实现用户登录了~~~

posted on 2018-11-22 10:43  LoaderMan  阅读(799)  评论(0)  编辑  收藏  举报

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