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@WebServlet Login and Logout Example
Posted on: December 16, 2011 at 12:00 AM

In this tutorial I am giving a very simple example which will demonstrate how you can create a login page, how can you authenticate them at the time of login, and finally logged out them in servlet.

@WebServlet Login and Logout Example

In this tutorial I am giving a very simple example which will demonstrate how you can create a login page, how can you authenticate them at the time of login, and finally logged out them in servlet.

Example :

login1.html

<!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 Page</title>
</head>
<body>
<form method="get" action="RequestForwardExample">
<p>Give the following details</p>
<table>
<tr><td>Name </td> <td><input type="text" name="name"/></td></tr>
<tr><td>Password </td> <td> <input type="password" name="psw"/></td></tr>
<tr><td></td> <td><input type="submit" value="submit"/></td></tr>
</table>
</form>
</body>
</html>

RequestForwardExample.java

package roseindia.requestDispatcherExample;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
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(name= "RequestForwardExample",
urlPatterns= {"/RequestForwardExample"})
public class RequestForwardExample extends HttpServlet
{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
{
response.setContentType("text/html");
PrintWriter out= response.getWriter();

String name= request.getParameter("name");
String psw= request.getParameter("psw");

String className= "com.mysql.jdbc.Driver";
String url= "jdbc:mysql://192.168.10.13/data";
String user= "root";
String password= "root";

Connection con;
PreparedStatement ps;
ResultSet rs;

try
{
Class.forName(className);
con= DriverManager.getConnection(url, user, password);

String sql= "SELECT name FROM login WHERE name = '"+name+"' AND password = '"+psw+"'";
ps= con.prepareStatement(sql);
rs= ps.executeQuery();
if(rs.next())
{
HttpSession session= request.getSession();
String n= rs.getString("name");
session.setAttribute("name", n);

ServletContext context= getServletContext();
RequestDispatcher rd= context.getRequestDispatcher("/ForwardTesterServlet");
rd.forward(request, response);
}
else
{
ServletContext context= getServletContext();
RequestDispatcher rd= context.getRequestDispatcher("/login1.html");
out.println("<font color=red>invalid user name or password</font>");
rd.include(request, response);
}

con.close();
ps.close();
rs.close(); 
}
catch(ClassNotFoundException cx)
{
out.println();
}
catch(SQLException sx)
{
out.println();
}
}
}

ForwardTesterServlet.java

package roseindia.requestDispatcherExample;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
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("/ForwardTesterServlet")
public class ForwardTesterServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
response.setContentType("text/html");
PrintWriter out= response.getWriter();
HttpSession session= request.getSession();
String name= (String)session.getAttribute("name");
out.println("Welcome "+name);
out.println("<h4>You are successfully logged in<h4>");
out.println("<html><body>");
out.println("<form method=get action= LogOutServlet>");
out.println("<input type=submit value=logout></input>");
out.println("</form></body></html>");
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
doGet(request, response);
}
}

LogOutServlet.java

package roseindia.requestDispatcherExample;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
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("/LogOutServlet")
public class LogOutServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
response.setContentType("text/html");
PrintWriter out= response.getWriter();
HttpSession session= request.getSession();
session.invalidate();
out.println("<font color=red><b>You have been successfully logged out</b></font>");
out.println("<font color=green><b>Login again</b></font>");
ServletContext context= getServletContext();
RequestDispatcher rd= context.getRequestDispatcher("/login1.html");
rd.include(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
doGet(request, response);
}

}

Output :

When you will execute the above example you will get the output as :

When you will click on "submit" button you will get the output as :

But to logout when you will click on "logout" button you will get the output as :

Download Source Code

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