JavaWeb基础 Cookie 记录用户名

时间：2017-12-06 20:09:37 阅读：244 评论：0 收藏：0 [点我收藏+]

标签：boolean ssi put 定位 web string nbsp response input

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　　好好学习合思考，尊师重道存感恩。叶见寻根三返一，江河湖海同一体。
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       javaEE：7
       javaSE：1.8
          JSTL：1.2.2
      server：tomcat 8.5
    browser：Chrome/Firefox
             os：windows7 x64
            ide：MyEclipse 2017

项目结构

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web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>Day11</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
  	<servlet-name>LoginServlet</servlet-name>
  	<servlet-class>com.jizuiku.servlet.LoginServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
  	<servlet-name>LoginServlet</servlet-name>
  	<url-pattern>/LoginServlet</url-pattern>
  </servlet-mapping>
  
</web-app>

LoginServlet.java

package com.jizuiku.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 
 * 
 * @author 博客园-给最苦
 * @version V2017.11.21
 */
public class LoginServlet extends HttpServlet {

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub

	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		// 处理中文
		request.setCharacterEncoding("utf-8");
		// 获取
		String username = request.getParameter("username");
		String password = request.getParameter("password");

		// 检验用户名和密码是否正确
		boolean isCorrectUsername = "jizuiku".equalsIgnoreCase(username);
		boolean isCorrectPassword = "jizuiku".equalsIgnoreCase(password);

		if (isCorrectUsername && isCorrectPassword) {
			// 登陆成功
			
			// 向session中保存一下username
			request.getSession().setAttribute("username", username);
			
			// 保存用户信息到cookie中
			Cookie cookie = new Cookie("username", username);
			// cookie的保存时间为 1小时
			cookie.setMaxAge(60*60);
			response.addCookie(cookie);
			// 换到新的网址下
			// 这里用的是重定向
			response.sendRedirect("/Day11/sessionDemo/successOne.jsp");

		} else {

			// 登录失败
			// 保存提示信息
			request.setAttribute("message", "输入的信息有误");

			// 转发到login.jsp中，为什么不用重定向？
			// 因为信息保存在了request中
			RequestDispatcher rd = request.getRequestDispatcher("/sessionDemo/login.jsp");
			rd.forward(request, response);

		}

	}

}

<%@ 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 ‘login.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>
	<%
		String username = "";

		Cookie[] cookies = request.getCookies();
		
		if (cookies != null) {
			for (Cookie c : cookies) {
				if ("username".equalsIgnoreCase(c.getName())) {
					username = c.getValue();
					break;
				}
			}
		}
	%>
	<%
		String message = "";
		String msgFromLoginServlet = (String) request.getAttribute("message");
		if (msgFromLoginServlet != null) {
			message = msgFromLoginServlet;
		}
	%>
	<h1><%=message %></h1>
	<h1>登录表单</h1>
	<form action="/Day11/LoginServlet" method="post">
		用户名:<input type="text" name="username" value="<%=username%>" /> 密 码:
		<input type="password" name="password" /> <input type="submit"
			value="登录" />
	</form>
</body>
</html>

successOne.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 ‘successOne.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>
	<%
		// 因为这个页面的定位是 访问控制页面，只有 登陆成功的人才能查看
		// 所以，为了防止有人绕过登录页面 进行访问，所以写了这段代码
		// 但即使是这样写了，还是不够的。信息安全领域很强的！
		String username = (String) session.getAttribute("username");
		
		if (username == null) {
			request.setAttribute("message", "请先登录");
			// 转发！
			request.getRequestDispatcher("/sessionDemo/login.jsp").forward(request, response);
			// return;
		}
		
		
	%>
	<h1>
		欢迎<%=username%>!
	</h1>
</body>
</html>

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