JavaWeb_使用Servlet + HttpSession实现简单用户登陆

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学习Servlet之后，觉得HttpSession的作用还是比较大的，可以通过HttpSession机制往页面传值，以下是一个简单的例子

1.新建登陆页

<%@ 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>登陆页</title></head><body><center>   <div style="margin-top:100px">   <h2>请登陆</h2>      <form action="login.do" method="post">           <input type="text" name="username" id="username"/><br>           <input type="password" name="pwd" id="pwd"/><br>           <input type="submit" value="登陆"/>                      </form>      </div></center></body></html>

2.登陆成功后跳转至首页

<%@ 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>欢迎页</title></head><body><h1>登陆成功，当前用户：${userName}</h1><h2>登陆时间:${logindate }</h2></body></html>

3.登陆失败信息提示页面，可以通过超链接跳转至登陆页

<%@ 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> <p>${msg }</p><br> <a href="../pages/login.jsp"><p>点此重新登陆</p></a> </body></html>

4.创建用户模型

package com.evian.model;public class User {private String uname;private String password;private String sex;public String getUname() {return uname;}public void setUname(String uname) {this.uname = uname;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public User(String uname, String password, String sex) {super();this.uname = uname;this.password = password;this.sex = sex;}public User() {super();// TODO Auto-generated constructor stub}}

5.用户Service，我只是做个小例子，所以没有链接数据库，只是通过Java数组存储几个用户

package com.evian.util;import com.evian.model.User;public class UserService {User user1 = new User("张三", "123123", "男");User user2 = new User("李白", "110110", "女");User user3 = new User("王名", "123456", "男");User[] users = { user1, user2, user3 }; //创建数组用于保存user    /** * 根据用户名匹配user对象并返回给servlet * @param username * @return */public User userlogin(String username) {User u = null;for (User user : users) {if (username.equals(user.getUname())) {u = user;}}return u;}}

6.登陆Action

package com.evian.controller;import java.io.IOException;import java.util.Date;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import com.evian.model.User;import com.evian.util.UserService;@SuppressWarnings("serial")@WebServlet("/UserServlet")public class UserServlet extends HttpServlet {protected void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {request.setCharacterEncoding("utf-8");// 设置请求信息字符编码response.setCharacterEncoding("utf-8");// 设置响应信息字符编码String userName = request.getParameter("username");// 获取登陆页用户名信息String password = request.getParameter("pwd");// 获取登陆页用户密码信息UserService us = new UserService();User user = us.userlogin(userName);// 调用UserService方法，返回用户名等于登陆页用户名的User对象HttpSession session = request.getSession();// 创建Session对象/** * 判断密码是否正确 */if (user != null) {if (user.getPassword().equals(password)) {session.setAttribute("userName", userName);session.setAttribute("logindate", new Date());response.sendRedirect("/TestSession/pages/index.jsp");// 密码正确跳转至index页面} else {session.setAttribute("msg", "密码错误");response.sendRedirect("/TestSession/pages/error.jsp");// 密码错误停留在login页面}} else {session.setAttribute("msg", "用户名不存在");response.sendRedirect("/TestSession/pages/error.jsp");// 用户名错误停留在login页面}}}

7.web.xml配置文件

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">  <display-name>TestSession</display-name>  <welcome-file-list>    <welcome-file>/pages/login.jsp</welcome-file>  </welcome-file-list>  <servlet>    <servlet-name>userLogin</servlet-name>    <servlet-class>com.evian.controller.UserServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>userLogin</servlet-name>    <url-pattern>/login.do</url-pattern>  </servlet-mapping></web-app>

8.运行效果图

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