Unable to POST JSON object from Javascript to a Servlet via AJAX

Question

I am trying to POST a JSON object to a servlet via AJAX. However, the object is null in the servlet. I am unable to figure out what's wrong with this code.

JAVASCRIPT

function submitValues(event, val1, val2) 
{    
var xmlHttpObj = new XMLHttpRequest();                
            if(window.XMLHttpRequest) 
            {
                xmlHttpObj = new XMLHttpRequest();                    
             }
            else if(window.ActiveXObject)
            {
                xmlHttpObj = new ActiveXObject("Microsoft.XMLHttp");

            }


     var jsonObject =  submitTheValues(event, val1, val2);
       alert("json is:" +jsonObject);
     var json = JSON.stringify(jsonObject);
       alert("json after stringify:" +json);

        xmlHttpObj.open("POST", "../myapp/myservlet", true);
        xmlHttpObj.setRequestHeader("Content-type", "application/json");                    
        xmlHttpObj.send(json);

}  

SERVLET

String jsonObj = request.getParameter("json");

Answer 1

If you want to receive the data as a parameter you'll have to send it as application/x-www-form-urlencode.

xmlHttpObj.open("POST", "../myapp/myservlet", true);
xmlHttpObj.setRequestHeader("Content-type", "application/x-www-form-urlencode");                    
xmlHttpObj.send('json='+encodeURIComponent(json));