これは、この Web サイトでの最初のクエリです。皆さんが私のプロジェクトを完了するのを手伝ってくれることを願っています. 事前にthnx。
プロジェクトの完全なコードを貼り付けました。解決策が必要です（つまり、ログアウトボタンをクリックした後、ユーザーはログインページに移動する必要があり、戻るボタンをクリックしようとすると、前のページに移動せず、同じログインページにいる必要があります。
index.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Login</title>
<style type="text/css">
.header {
width: 250px;
height: 50px;
background-color: #6495ED;
font-family: verdana;
font-size: 20px;
font-weight: bold;
}
.header2 {
width: 250px;
height: 50px;
background-color: "#FFE4B5";
font-family: verdana;
font-size: 12px;
font-weight: bold;
}
</style>
<script type="text/javascript">
<%String name = (String) request.getAttribute("status");%>
var alertMsg = "<%=name%>
";
if (alertMsg != "null" && alertMsg != '') {
alert(alertMsg);
}
</script>
<script src="<%=request.getContextPath()%>/gen_validatorv4.js"
type="text/javascript"></script>
</head>
<body>
<form name="login" action="LoginServlet" method="post">
<center>
<a href="index.jsp" class="header2" style="background-color: #FFE4B5";>Home</a>
</center>
<center>
<table
style="background-color: #CAE1FF; border-color: 1px solid red;">
<tr>
<td align="center" class="header" colspan="2">Login</td>
</tr>
<tr height="50px">
<td align="" class=""
style="padding-left: 10px; font-family: tohoma;">Username</td>
<td><input type="text" name="username" style="width: 150px;" />
</td>
</tr>
<tr height="50px">
<td align="" class=""
style="padding-left: 10px; font-family: tohoma;">Password</td>
<td><input type="password" name="password"
style="width: 150px;" /></td>
</tr>
<tr height="50px">
<td></td>
<td align="center" colspan="0">
<table style="width: 100%;">
<tr>
<td align="left"><input type="submit" name="submit"
value="Login"
style="width: 60px; height: 25px; background: #436EEE; color: white !important; border: 1px solid #0000EE;; border-radius: 2;" />
</td>
<td><input type="reset" value="Cancel"
style="width: 60px; height: 25px; background: #436EEE; color: white !important; border: 1px solid #0000EE;; border-radius: 2;" />
</td>
<td><a href="register.jsp">New User?</a></td>
</tr>
</table></td>
</tr>
</table>
</center>
</form>
<script type="text/javascript">
var formValidator = new Validator("login");
formValidator.addValidation("username", "req",
"Please enter your User Name");
formValidator.addValidation("password", "req",
"Please enter your Password");
</script>
</body>
</html>
LoginServlet.java
package pack;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
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;
/**
* Servlet implementation class LoginServlet
*/
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet implements Filter {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public LoginServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
@Override
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String loginName = null;
String loginPass = null;
String status;
HttpSession session = request.getSession();
String username = request.getParameter("username");
String password = request.getParameter("password");
String jdbcDriver = "com.mysql.jdbc.Driver";
String dbURL = "jdbc:mysql://localhost:3306/studentdetails";
String uname = "root";
String pwd = "admin";
try {
Class.forName(jdbcDriver);
Connection con = DriverManager.getConnection(dbURL, uname, pwd);
Statement stmt = con.createStatement();
ResultSet rs;
String query = "SELECT username, password FROM registration WHERE username = '"
+ username + "' AND password = '" + password + "'";
System.out.println(query);
stmt.executeQuery(query);
boolean permission = false;
rs = stmt.getResultSet();
while (rs.next()) {
permission = true;
loginName = rs.getString("username");
loginPass = rs.getString("password");
}
System.out.println(loginName);
System.out.println(loginPass);
rs.close();
stmt.close();
if (permission == true) {
request.getSession(true);
session.setAttribute("username", loginName);
RequestDispatcher redis = request
.getRequestDispatcher("/WEB-INF/pages/list.jsp");
redis.forward(request, response);
} else {
System.out.println("Permission denied");
status = "Username not yet registered";
request.setAttribute("status", status);
RequestDispatcher redis = request
.getRequestDispatcher("index.jsp");
redis.forward(request, response);
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
@Override
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
HttpSession session = request.getSession(false);
if (session != null && session.isNew()) {
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
chain.doFilter(request, response);
} else {
response.sendRedirect("index.jsp");
}
}
@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
}
}
list.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Expires" content="-1">
<meta http-equiv="CACHE-CONTROL" content="NO-CACHE">
<title>Insert title here</title>
<script type="text/javascript">
function logout() {
session.removeAttribute("username");
request.getSession().invalidate();
response.sendRedirect("index.jsp");
}
</script>
</head>
<body>
<form action="LoginServlet" name = "list">
<p><%if(session.getAttribute("username")!=null){
%>
<%session.getAttribute("username");%></p>
<%} %>
<input type="button" value = "Logout" onclick="logout();"/>
</form>
</body>
</html>
web.xml
<?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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
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>SessionManagement</display-name>
<servlet>
<servlet-name>Session</servlet-name>
<servlet-class>pack.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<filter>
<filter-name>noCacheFilter</filter-name>
<filter-class>pack.LoginServlet</filter-class>
</filter>
<filter-mapping>
<filter-name>noCacheFilter</filter-name>
<url-pattern>/list.jsp</url-pattern>
</filter-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>