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**rajasri** · 12-13-2011, 05:02 AM

Authentication in webapplication using jsp and servlet is easy to do.
The Page that contains the forms are placed in jsp page and the action event is redirected to a servlet where authentication happens if authentication is success it redirect to authenticated page or else redirect to login page with message incorrect username/password.
Create a basic table in mysql or any database with two fields username and password and load the values for that.
Create a file login.jsp with code below and save in loginsystem folder in webapps of tomcat.
login.jsp

Quote:<html>
<head>
<script>

Quote:</script>
</head>
<body>

<form action ="login" method="post" name="login">

<p> </p>

<font color="#FF3300" size="6"> <a href="http://s2sgateway.com">Tutorial by S2SGATEWAY.COM</a>!!!!!!!!!</font></p>

<a title="Press To Go Back" href="login.jsp" style="text-decoration: none">
<font color="#FFFFFF" face="Bauhaus 93" size="4"><-- BACK</font></a></p>
<div align="center">
<center>
<div align="center">
<center>
<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#0099cc" width="51%" id="AutoNumber1" bgcolor="#0099CC" height="134">
<tr>
<td width="100%" colspan="3" height="19">
<p align="center">
<b><font face="Verdana" color="#00FF00">ADMIN LOGIN
</font></b></p>

</td>
</tr>
<tr>
<td width="30%" height="23"><font face="Verdana" size="2" color="#800080">
USER NAME</font></td>
<td width="72%" colspan="2" height="23"><font color="#800080"><input type="text" name="user" size="20" onload = 'T1.focus();'></font></td>
</tr>
<script>
focus();
</script>

<tr>
<td width="30%" height="23"><font face="Verdana" size="2" color="#800080">
PASSWORD</font></td>
<td width="72%" colspan="2" height="23"><font color="#800080"><input type="password" name="pass" size="20">
</font> </td>
</tr>

<tr>
<td width="30%" height="23"> </td>
<td width="72%" colspan="2" height="23"> </td>
</tr>
<tr>
<td width="30%" height="26"> </td>
<td width="18%" height="26">
<p align="left"><font color="#800080"><input type="submit" value="Login" name="B1" onclick = 'return checkNull();'></font></td>
<td width="54%" height="26"><font color="#800080"><input type="reset" value="Reset" name="B2"></font></td>
</tr>
</table>

</center>
</div>
<p align="left"><font color="#008080"> </font></p>

<p align="left"><font color="#008080">
</font></p>

<p align="left"><font color="#008080">
</font></p>

</center>
</div>
</form>
</body>
</html>

Now create a java file named login.java with code below and compile it and place the class in web-inf/classes folder.
login.java

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.*;
import javax.servlet.http.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class login extends HttpServlet {

public login() {
super();
}

public void destroy() {
super.destroy();

}

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

String a=request.getParameter("user");
String b=request.getParameter("pass");
HttpSession s=request.getSession();
login l =(login)s.getAttribute("a");

System.out.println(a);
try
{
Class.forName("com.mysql.jdbc.Driver");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost/dbname","username","password");

Statement st=null;
String c="select * from login where username='"+a+"' AND pass='"+b+"'";
st=con.createStatement();
ResultSet rs=st.executeQuery©;

if(rs.next())
{
response.sendRedirect("success.jsp");

}
else
response.sendRedirect("login.jsp");

}
catch(Exception e){}
}

public void init() throws ServletException {

}

}
Now add the servlet setting in web.xml like below

web.xml

<wep-app>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>login</servlet-name>
<servlet-class>login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login/*</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>home.html</welcome-file>
</welcome-file-list>
</web-app>
Thats it now you can run by visiting your tomcat http://localhost:8080/loginsystem/login.jsp
Any doubt ask us happy coding