Question

In my app im using JSP as view,servlet as controller,hibernate as model..

in that app jsp pages im have to fill form while creating new user with fields like username and all.

now i want to use AJAX code to check if username name with entered name in form is already there in the database or not…

can any1 guide me how to write coding for this as well as the control flow..

i have googled but didnt got any idea how to do this requirement..

thanks in advance

Answer 1

In Jsp

<script type="text/javascript">
    function VerifyUsername()
    {
        //alert("In Verify Method");
        var name=document.getElementById("username").value;
        //alert(name);
        var xmlhttp;
        if (window.XMLHttpRequest)
        {// code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp=new XMLHttpRequest();
            //alert("http");
         }
        else
        {// code for IE6, IE5
            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
            alert("http active");
        }
        xmlhttp.onreadystatechange=function()
        {
            //alert("in Function()");
            if (xmlhttp.readyState==4 && xmlhttp.status==200)
            {
                try
                {
                    //alert("In Try");
                    document.getElementById("errorpass").innerHTML=xmlhttp.responseText;
                    /*var response = xmlhttp.responseText;
                    alert(response);
                    if(response.toString()=='notmatch')
                    {
                        alert("Ok");
                        document.getElementById("errorpass").innerHTML ="OK";
                    }
                    if(response =='match')
                    {
                        alert("Not Ok");
                        document.getElementById("errorpass").innerHTML ="Take Other Name.";
                    }*/
                }
                catch(ex)
                {
                    alert("Exception in function "+ex);
                }
            }
        }
        //xmlhttp.open("POST","servlet/UsernamePresence_Serv?UserId"+name,true);
        xmlhttp.open("POST","servlet/UsernamePresence_Serv?"+name,true);
        var params = "UserId="+name;
        xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
        xmlhttp.setRequestHeader("Content-length", params.length);
        xmlhttp.setRequestHeader("Connection", "close"); 
        xmlhttp.send(params);
    }
</script>

in Servlet

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

    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    try
    {
        Session session=Hibernate_Class.sessionObject();
        String userID=null;
        userID = request.getParameter("UserId");

        login_model loginModel_Obj=new login_model();
        loginModel_Obj._Name=userID;
        System.out.print("at "+userID);
        boolean username_bool=Hibernate_Class.usernamePresence(loginModel_Obj, session);

        if (username_bool)
        {
            out.println("Username Present In Database");
        }
        else
        {
            out.println("Username Not Present In Database");
        }

    }
    finally{}
    out.close();
}