how to keep register page data if register fails

i mean to say- now there is one register page with fields such as first name, last name,username,.... ok. so now i will fill in the details and when i click submit button and say the register fails because of similar username already exists. now the remaining fields should not clear except the username. how do we achieve that? this s my code:

register.jsp:

<!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>Registration</title>
<script type="text/javascript">
function validate()
{
	
	if(document.getElementById('fname').value == "")
	{
		alert("Please enter the First Name");
		document.getElementById('fname').value = document.getElementById('fname').value;
		document.getElementById('fname').focus();
		return false;
	}
	if(document.getElementById('lname').value == "")
	{
		alert("Please enter the Last Name");
		document.getElementById('lname').value = document.getElementById('lname').value;
		document.getElementById('lname').focus();
		return false;
	}
	if(document.getElementById('email').value == "")
	{
		alert("Please enter the Email");
		document.getElementById('email').value = document.getElementById('email').value;
		document.getElementById('email').focus();
		return false;
	}
	if(document.getElementById('uname').value == "")
	{
		alert("Please enter the User Name");
		document.getElementById('uname').value = document.getElementById('uname').value;
		document.getElementById('uname').focus();
		return false;
	}
	if(document.getElementById('pwd').value == "")
	{
		alert("Please enter the Password");
		document.getElementById('pwd').value = document.getElementById('pwd').value;
		document.getElementById('pwd').focus();
		return false;
	}
	
	return true;
}

</script>
</head>
<body style="background-color: pink">
<h1 align="center">Registration Page</h1>

<form method="post" action="Register"  onsubmit="return validate()">
<div style="margin-left:10%;margin-top: 5%">
*First Name: <input type="text"  id="fname" name="fname"/><br><br>
*Last Name: <input type="text" id="lname" name="lname"/><br><br>
*Email:         <input type="text" id="email" name="email"/><br><br>
*Username:  <input type="text" id="uname" name="uname"/><br><br>
*Password:  <input type="password" id="pwd" name="pwd"/> <br><br>
</div>
<div style="margin-left: 20%">
<input type="submit" value="Register" />
<input type="reset" value="Reset" />
</div>
<div style="margin-left: 10%;margin-top: 10%">
* indicates mandatory fields
</div>

<% if(request.getAttribute("message")!=null){ %>
									
	<div style="text-decoration:blink;color:red;text-align: center;">Username already exists</div>
							
	<%}%>

</form>

</body>
</html>

This is servlet class:

RegisterServlet.java:

package com.samartha;

import java.io.IOException;
import java.sql.*;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class RegisterServlet
 */
public class RegisterServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public RegisterServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String fname=request.getParameter("fname");
		String lname=request.getParameter("lname");
		String email=request.getParameter("email");
		String uname=request.getParameter("uname");
		String pwd=request.getParameter("pwd");
		
		String userName="";
		
		
		
		try{
	         Class.forName("com.mysql.jdbc.Driver").newInstance();
	           Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root123");
	           Statement stmt=con.createStatement();
	           String sql="insert into users(fname,lname,email,uname,pwd) values('"+fname+"','"+lname+"','"+email+"','"+uname+"','"+pwd+"')";
	           System.out.println("rows affected by insert "+stmt.executeUpdate(sql));
	           System.out.println("Data is successfully inserted!");
	           String sql1="SELECT uname,pwd FROM users where uname =\'" + uname + "\'";
	           ResultSet rs = stmt.executeQuery(sql1);
	           
	           while(rs.next()){
	        	   userName = rs.getString(1);
	        	   System.out.println("userName=>"+userName);
	        	
				}
	        }
			catch (SQLException s) {
			System.out.print(s);
			s.printStackTrace();
		}
	        catch(Exception e){
	        System.out.print(e);
	        e.printStackTrace();
	        }
	        
	    if(uname.equals(userName)){
		RequestDispatcher rd=null;
		rd=request.getRequestDispatcher("registersuccess.html");
		rd.forward(request, response);
	    }
	    else
	    {
	    	RequestDispatcher rd=null;
			rd=request.getRequestDispatcher("register.jsp");
			request.setAttribute("message", "success");
			rd.forward(request, response);
	    }
		
	}
}

Hi,
Use an ajax validation for username .

All form elements have a value attribute that can be used to set their initial values. You can use it to restore the submitted values to the elements.

Or, as pointed out, using Ajax to submit the values causes the original form to stay on the browser while the request is being processed in the background.

The latter is how I do a lot of form submissions, but it's a little more advanced and requires JavaScript.

Bear Bibeault wrote:All form elements have a value attribute that can be used to set their initial values. You can use it to restore the submitted values to the elements.

.

how do i do this?

Get the values from the request and use JSP to set them into the value attributes.

Ajax is the best way, without sending the data to the server it will validates at the client side itself...