在前面一节教程文章中,已经介绍了什么是HttpSession
,如何存储和从会话对象获取数据。
我们可以绑定HttpSession
实例上的对象,并使用setAttribute
和getAttribute
方法获取对象的数据信息。
在这里,将演示一个在不使用数据库连接的情况下,创建一个真实的登录和注销应用程序。假设有一个用户名是:admin
,它密码是admin123
。
注: 访问这里查看:使用cookies登录和注销的应用程序示例 ,有助于学习本节文章的内容。
在这个例子中,我们创建了3
个链接页面:登录,注销和个人资料。实现功能:用户在登录之前不能进入个人资料页面。如果用户已经注销,则需要再次登录才能访问个人资料页面。
在这个应用程序中,创建了以下几个文件。
- index.html - Web应用程序首页。
- link.html - 链接页面。
- login.html - 登录页面。
- LoginServlet.java - 登录Servlet处理。
- LogoutServlet.java - 注销Servlet处理。
- ProfileServlet.java - 用户个人资料Servlet。
- web.xml - Servlet配置文件。
打开Eclipse,创建一个动态Web项目:SessionLoginout,其完整的目录结构如下所示 -
以下是这个项目中的几个主要的代码文件。
文件:index.html -
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Session登录注销实例</title>
</head>
<body style="text-algin: center;">
<h2>欢迎Session登录注销应用程序</h2>
<a href="login.html">登录</a>|
<a href="logout">注销</a>|
<a href="profile">个人信息</a>
</body>
</html>
文件:link.html -
<a href="login.html">登录</a>|
<a href="logout">注销</a>|
<a href="profile">个人信息</a>
<hr>
文件:login.html -
<div style="text-algin: center; padding-top:12px;">
<form action="login" method="post">
用户名:<input type="text" name="username"> 密码:<input type="password"
name="password"><input type="submit" value="登录">
</form>
</div>
</body>
</html>
文件:LoginServlet.java -
package com.yiibai;
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;
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
request.setCharacterEncoding("UTF-8");
request.getRequestDispatcher("link.html").include(request, response);
String username = request.getParameter("username");
String password = request.getParameter("password");
if (username == null) {
username = "";
}
if (password == null) {
password = "";
}
if (username.equals("admin") && password.equals("admin123")) {
out.print("Welcome, " + username);
HttpSession session = request.getSession();
session.setAttribute("username", username);
session.setAttribute("nickname", "苏小牛");
session.setAttribute("age", "21");
} else {
out.print("<font style='color:rec;'>对不起,用户名或密码错误!</font>");
request.getRequestDispatcher("login.html").include(request, response);
}
out.close();
}
}
文件:logoutServlet.java -
package com.yiibai;
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;
public class LogoutServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
request.setCharacterEncoding("UTF-8");
request.getRequestDispatcher("link.html").include(request, response);
HttpSession session = request.getSession();
// 清除数据
session.invalidate();
out.print("您已成功注销退出系统!");
out.close();
}
}
文件:ProfileServlet.java -
package com.yiibai;
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;
public class ProfileServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
request.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
request.getRequestDispatcher("link.html").include(request, response);
HttpSession session = request.getSession(false);
if (session != null) {
String name = (String) session.getAttribute("username");
String nickname = (String) session.getAttribute("nickname");
String age = (String) session.getAttribute("age");
out.print("您好, " + name + " 欢迎您来到个人信息中心!");
out.print("<hr/>个人信息如下, 昵称:" + nickname + " ,年龄:"+age);
} else {
out.print("请登录系统!");
request.getRequestDispatcher("login.html").include(request, response);
}
out.close();
}
}
文件: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>SessionLoginout</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.yiibai.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>ProfileServlet</servlet-name>
<servlet-class>com.yiibai.ProfileServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ProfileServlet</servlet-name>
<url-pattern>/profile</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LogoutServlet</servlet-name>
<servlet-class>com.yiibai.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LogoutServlet</servlet-name>
<url-pattern>/logout</url-pattern>
</servlet-mapping>
</web-app>
在编写上面代码后,部署此Web应用程序(在项目名称上点击右键->”Run On Server…”),打开浏览器访问URL: http://localhost:8080/SessionLoginout/ ,如果没有错误,应该会看到以下结果 -
点击“登录”,如下界面 -
使用用户名:admin
,密码:admin123
,点击登录成功后,如下界面 -
用户名或密码错误时,显示如下 -
点击“个人信息”链接,显示如下 -
点击“注销”链接,显示如下 -