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/ContentServlet.java

Created February 23, 2016 13:17
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Web App code for stackoverflow question
Raw
ContentServlet.java
package com.example.test;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet({"/home" })
public class ContentServlet extends HttpServlet{
private static final long serialVersionUID = -2907124992996374890L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
if(!SessionValidator.isSessionValid(request, response)){
RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
dispatcher.forward(request, response);
return;
}
RequestDispatcher dispatcher = request.getRequestDispatcher("home.jsp");
dispatcher.forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
doGet(request, response);
}
}
Raw
home.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>Home</title>
</head>
<body>
<%
String userId = (String) session.getAttribute("userId");
%>
<h1>You successfully logged in!!</h1>
<h2>Welcome <%=userId%></h2>
<a href="login?action=logout">logout</a>
</body>
</html>
Raw
login.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>
</head>
<body>
<%
String message = (String) request.getAttribute("message");
message = message==null ? "" : message;
%>
<form action="login" method="post">
<h3><%=message %></h3>
<label>Id: </label> <input type="text" name="userId">
<label>Password: </label> <input type="password" name="password">
<input type="submit" value="Login">
</form>
</body>
</html>
Raw
LoginServlet.java
package com.example.test;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
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;
@WebServlet({ "/", "/login" })
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 6893524305259610055L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String action = request.getParameter("action");
if("logout".equals(action)){
HttpSession session = request.getSession(false);
if(!SessionValidator.isSessionValid(request, response)){
RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
dispatcher.forward(request, response);
return;
}
session.invalidate();
}
RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
dispatcher.forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String userId = request.getParameter("userId");
String password = request.getParameter("password");
if("admin".equals(userId) && "pass1234".equals(password)){
HttpSession session = request.getSession();
session.invalidate();
session = request.getSession(true);
session.setAttribute("userId", userId);
response.sendRedirect("home");
}
else{
RequestDispatcher dispatcher = request.getRequestDispatcher("login.jsp");
request.setAttribute("message", "Invalid Login ID / password");
dispatcher.forward(request, response);
}
}
}
Raw
SessionValidator.java
package com.example.test;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class SessionValidator {
public static boolean isSessionValid(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
HttpSession session = request.getSession(false);
if(session==null || session.getAttribute("userId")==null){
request.setAttribute("message", "Session expired, login again");
return false;
}
return true;
}
}
Raw
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<display-name>mywebapp</display-name>
<session-config>
<session-timeout>5</session-timeout>
</session-config>
</web-app>
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