在前面一節(jié)教程文章中，已經介紹了什么是HttpSession，如何存儲和從會話對象獲取數據。
我們可以綁定HttpSession實例上的對象，并使用setAttribute和getAttribute方法獲取對象的數據信息。
在這里，將演示一個在不使用數據庫連接的情況下，創(chuàng)建一個真實的登錄和注銷應用程序。假設有一個用戶名是：admin，它密碼是admin123。
注： 訪問這里查看：使用cookies登錄和注銷的應用程序示例 ，有助于學習本節(jié)文章的內容。
在這個例子中，我們創(chuàng)建了3個鏈接頁面：登錄，注銷和個人資料。實現功能：用戶在登錄之前不能進入個人資料頁面。如果用戶已經注銷，則需要再次登錄才能訪問個人資料頁面。
在這個應用程序中，創(chuàng)建了以下幾個文件。
打開Eclipse，創(chuàng)建一個動態(tài)Web項目：SessionLoginout，其完整的目錄結構如下所示 -
以下是這個項目中的幾個主要的代碼文件。
文件：index.html -
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Session登錄注銷實例</title>
</head>
<body style="text-algin: center;">
<h2>歡迎Session登錄注銷應用程序</h2>
<a href="login.html">登錄</a>|
<a href="logout">注銷</a>|
<a href="profile">個人信息</a>
</body>
</html>
文件：link.html -
<a href="login.html">登錄</a>|
<a href="logout">注銷</a>|
<a href="profile">個人信息</a>
<hr>
文件：login.html -
<div style="text-algin: center; padding-top:12px;">
<form action="login" method="post">
用戶名：<input type="text" name="username"> 密碼：<input type="password"
name="password"><input type="submit" value="登錄">
</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", "蘇小牛");
session.setAttribute("age", "21");
} else {
out.print("<font style='color:rec;'>對不起，用戶名或密碼錯誤!</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();
// 清除數據
session.invalidate();
out.print("您已成功注銷退出系統!");
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 + " 歡迎您來到個人信息中心！");
out.print("<hr/>個人信息如下, 昵稱：" + nickname + " ，年齡："+age);
} else {
out.print("請登錄系統！");
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>
在編寫上面代碼后，部署此Web應用程序(在項目名稱上點擊右鍵->”Run On Server…”)，打開瀏覽器訪問URL： http://localhost:8080/SessionLoginout/ ，如果沒有錯誤，應該會看到以下結果 -
點擊“登錄”，如下界面 -
使用用戶名：admin ，密碼：admin123，點擊登錄成功后，如下界面 -
用戶名或密碼錯誤時，顯示如下 -
點擊“個人信息”鏈接，顯示如下 -
點擊“注銷”鏈接，顯示如下 -
掃碼關注鍍金池微信號
手機訂課，優(yōu)惠多多