Java Ajax Hello World needed

**Marcinnnn** · 08-31-2009, 02:05 PM

Hi,

I just need simple example of using AJAX with Java in web developing. Lets say we have just simple page

Code:

<html>
<header>
\\ stuff like title, meta, etc.
</header>
<body>
<div onclick="doAjax();" > whatever </div>
</body>
</html>

We have of course class in a package:

Code:

package app.rpc;

public class myClass extends HttpServlet {

	public void doGet(HttpServletRequest request, 
	           HttpServletResponse response) 
	        throws IOException, ServletException { 
	        
	       String something = request.getParameter("something");
	       
	           response.setContentType("text/xml"); 
	           response.setHeader("Cache-Control", "no-cache"); 
	           response.getWriter().write("It works! " + something); 
	    }		
}

I think that this class is just OK. And we of course need to have some javascript:

Code:

// yea I know that this will not work with ie6 but leave it
function initRequest() {
    if (window.XMLHttpRequest) {
        return new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        isIE = true;
        return new ActiveXObject("Microsoft.XMLHTTP");
    }
return false; 
}

// I think here problem comes

function doAjax() {
           var url = "myTomcatContext/app.rpc.myClass?something=Hello-World"; // I'm not sure if path is correct          
           var req = initRequest();
           req.onreadystatechange = function() {
               if (req.readyState == 4) {
                   if (req.status == 200) {
                       parseMessages(req.responseXML); // and not sure of this
                   } else if (req.status == 204){
                       clearTable();
                   }
               }
           }

           req.open("GET", url, true); // I would like also POST version - if someone can help I'll be thankful
           req.send(null);
    alert(response+ '!'); \\ I want all data ( "It works! Hello-world!" should be here)
}

Thanks in advance,
Marcin

**amrosama** · 08-31-2009, 02:24 PM

you can use responseText property instead, i think its working fine all you need to do is to see the results:
if you are using firefox get firebug plugin it will help you see the requests and responses by your page