<option value=”deepak1">deepak1</option>
<option value=”deepak2">deepak2</option>
</select>
</form>
<h3>
<span id=”firstname”></span> &nbsp;
<span id=”lastname”></span>
</h3>
</body>
</html>

The combo box, which is used to select one option, has “onchange” attribute, which is set to the JavaScript function “showUser ()”. This method is called every time user changes the user selection. To show the user details two components of id “firstname” and “lastname” is used which will be updated after getting the records corresponding to the particular user using Ajax.

“showUser ()” first tries to get HTTP request object maintaining the browser compatibility. In this example, this object is stored in the variable named “xmlHttp”. Read how to get HTTP request object on page 12

Next step is to determine which method should be invoked after getting the response from the server. In this example, the method “callback ()” is assigned for this purpose. Now the request for servlet “AJAXUserInfoServlet” is forwarded to the server along with user number as parameter.

AJAXUserInfoServlet.java

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.sql.*;
public class AJAXUserInfoServlet extends HttpServlet {
public void doGet( HttpServletRequest request, HttpServletResponse response ) throws
ServletException, IOException {
String username = request.getParameter(“username”);
response.setContentType(“text/xml”);
response.setHeader(“Cache-Control”, “no-cache”);
sendUserFirstLastName(username,response);
}
public void sendUserFirstLastName(String username,HttpServletResponse response) {
Connection con = null;
String url = “jdbc:mysql://192.168.10.59:3306/”;
String db = “javajazzup”;
String driver = “com.mysql.jdbc.Driver”;
String user = “root”;