Servlet--Session属性Attribute应用登录

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一、session属性Attribute

1、通过一个登录页面实现session的Attribute的设置和获取。

2、登录实例介绍：一共有3个Servlet，分别是 Login、One、Tow

3、业务逻辑介绍：

①、用户通过首页输入用户名和密码点击提交。用户名正确，跳转到Login可以访问One和Tow两个页面。

②、用户名字符少于2个，会提示登录失败，不能访问One和Tow页面。

③、没有登录直接访问One和Tow页面，会跳转到登录页面。并且url连接中会有个error=1错误的表示

二、实例

1、LoginServlet

package login;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;public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();//获取用户提交的用户名和密码String name = request.getParameter("name");String pwd = request.getParameter("pwd");//将用户名称添加到session的属性中if(name!=null && name.trim().length()>2){//将用户名添加到sessionrequest.getSession().setAttribute("name",name);//如果session属性有用户名可以访问其他页面out.print("<a href='"+request.getContextPath()+"/One'>访问one</a><br/>");out.print("<a href='"+request.getContextPath()+"/Tow'>访问tow</a><br/>");}else{out.print("你的登录失败，不能访问其他页面");}}}

2、OneServlet

package login;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;public class One extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();if(request.getSession().getAttribute("name")==null){out.print("没有登录，不能访问One页面，请先登录");response.sendRedirect(request.getContextPath()+"/index.jsp?error=1");}else{out.print("你好："+request.getSession().getAttribute("name")+"登录成功了！");}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();}}

3、TowServlet

package login;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;public class TowServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();if(request.getSession().getAttribute("name")==null){out.print("没有登录，不能访问Tow页面，请先登录");response.sendRedirect(request.getContextPath()+"/index.jsp?error=2");out.print(request.getContextPath());}else{out.print("你好"+request.getSession().getAttribute("name")+"登录成功");}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {}}

4、index.jsp

<%@ 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>    <base href="<%=basePath%>">        <title>My JSP 'index.jsp' starting page</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body>    This is my JSP page. <br>    <form action="LoginServlet" method="post">    用户名：<input type="text" name="name" value=""/><br/>    密    码：   <input type="password" name="pwd" value=""/><br/>    <input type="submit" value="提交"/>        </form>  </body></html>

5、web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app version="3.0"    xmlns="http://java.sun.com/xml/ns/javaee"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">  <servlet>    <description>This is the description of my J2EE component</description>    <display-name>This is the display name of my J2EE component</display-name>    <servlet-name>LoginServlet</servlet-name>    <servlet-class>login.LoginServlet</servlet-class>  </servlet>  <servlet>    <description>This is the description of my J2EE component</description>    <display-name>This is the display name of my J2EE component</display-name>    <servlet-name>One</servlet-name>    <servlet-class>login.One</servlet-class>  </servlet>  <servlet>  <servlet-name>TowServlet</servlet-name>  <servlet-class>login.TowServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>LoginServlet</servlet-name>    <url-pattern>/LoginServlet</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>One</servlet-name>    <url-pattern>/One</url-pattern>  </servlet-mapping>  <servlet-mapping>  <servlet-name>TowServlet</servlet-name>  <url-pattern>/Tow</url-pattern>  </servlet-mapping></web-app>

6、测试

A、在浏览器中输入：http://127.0.0.1:8080/test08_2/

B、填写用户名和密码，点击提交

C、登录成功，跳转到LoginServlet页面，可以点击访问One和访问Tow

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