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May 19, 2008 at 9:10 PM
Hi
<!DOCTYPE HTML PUBLIC ?-//W3C//DTD HTML 4.01 Transitional//EN?>
<html>
<head>
<title>AJAX and Servlet</title>
<script language=?javascript?>
var xmlHttp;
function checkUserExist() {
var username = document.getElementById(?username?).value;
var url = ?/Ajax/AJAXCheckUserServlet?username=? + username;
if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}
else if(window.ActiveXObject){
xmlHttp = new ActiveXObject(?Microsoft.XMLHTTP?);
}
xmlHttp.open(?Get?,url,true);
xmlHttp.onreadystatechange = callback;
xmlHttp.send(null);
}
function callback() {
if( xmlHttp.readyState==4 ){
if( xmlHttp.status==200 ) {
document.getElementById(?text?).innerHTML = ?<br/><b>?+xmlHttp.responseText+?</
b>?;
}
}
}
function focusIn(){
document.getElementById(?username?).focus( );
}
</script>
</head>
<body onload=?focusIn();?>
<form>
User Name <input type=?text? id=?username? name=?username? />
<input type=?button? value=?Check User Name Availability? onClick=?checkUserExist()?/>
<div id=? text? ></div>
</form>
</body>
</html>
---------------------------------------------------
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.sql.*;
public class AJAXCheckUserServlet extends HttpServlet {
public void doGet( HttpServletRequest request, HttpServletResponse response ) throws
ServletException, IOException {
String username = request.getParameter(?username?);
boolean isExist = check(username);
response.setContentType(?text/html?);
response.setHeader(?Cache-Control?, ?no-cache?);
if(isExist){
response.getWriter().write(?User Name exists. Please select other name.?);
}
else{
response.getWriter().write(?Congratulations....User Name is available.?);
}
}
public boolean check(String username) {
Connection con = null;
String url = ?jdbc:mysql://192.168.10.59:3306/?;
String db = ?javajazzup?;
String driver = ?com.mysql.jdbc.Driver?;
String user = ?root?;
String pass = ?root?;
boolean isExist= false;
try{
Class.forName(driver).newInstance();
con = DriverManager.getConnection(url+db, user, pass);
try{
Statement st = con.createStatement();
ResultSet res = st.executeQuery(?SELECT user_name FROM users?);
while (res.next()) {
String un = res.getString(?user_name?);
if(username.equals(un)){
con.close();
isExist = true;
break;
}
}
con.close();
}
catch (SQLException s){
System.out.println(?SQL code does not execute.?);
}
}
catch (Exception e){
e.printStackTrace();
}
return isExist;
}
}
---------------------------------
<!DOCTYPE HTML PUBLIC ?-//W3C//DTD HTML 4.01 Transitional//EN?>
<html>
<head>
<title>AJAX and Servlet</title>
<script language=?javascript?>
var xmlHttp;
function checkUserExist() {
var username = document.getElementById(?username?).value;
var url = ?/Ajax/AJAXCheckUserServlet?username=? + username;
if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}
else if(window.ActiveXObject){
xmlHttp = new ActiveXObject(?Microsoft.XMLHTTP?);
}
xmlHttp.open(?Get?,url,true);
xmlHttp.onreadystatechange = callback;
xmlHttp.send(null);
}
function callback() {
if( xmlHttp.readyState==4 ){
if( xmlHttp.status==200 ) {
document.getElementById(?text?).innerHTML = ?<br/><b>?+xmlHttp.responseText+?</
b>?;
}
}
}
function focusIn(){
document.getElementById(?username?).focus( );
}
</script>
</head>
<body onload=?focusIn();?>
<form>
User Name <input type=?text? id=?username? name=?username? />
<input type=?button? value=?Check User Name Availability? onClick=?checkUserExist()?/>
<div id=? text? ></div>
</form>
</body>
</html>
---------------------------------------------------
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.sql.*;
public class AJAXCheckUserServlet extends HttpServlet {
public void doGet( HttpServletRequest request, HttpServletResponse response ) throws
ServletException, IOException {
String username = request.getParameter(?username?);
boolean isExist = check(username);
response.setContentType(?text/html?);
response.setHeader(?Cache-Control?, ?no-cache?);
if(isExist){
response.getWriter().write(?User Name exists. Please select other name.?);
}
else{
response.getWriter().write(?Congratulations....User Name is available.?);
}
}
public boolean check(String username) {
Connection con = null;
String url = ?jdbc:mysql://192.168.10.59:3306/?;
String db = ?javajazzup?;
String driver = ?com.mysql.jdbc.Driver?;
String user = ?root?;
String pass = ?root?;
boolean isExist= false;
try{
Class.forName(driver).newInstance();
con = DriverManager.getConnection(url+db, user, pass);
try{
Statement st = con.createStatement();
ResultSet res = st.executeQuery(?SELECT user_name FROM users?);
while (res.next()) {
String un = res.getString(?user_name?);
if(username.equals(un)){
con.close();
isExist = true;
break;
}
}
con.close();
}
catch (SQLException s){
System.out.println(?SQL code does not execute.?);
}
}
catch (Exception e){
e.printStackTrace();
}
return isExist;
}
}
---------------------------------
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