无法通过AJAX将JSON对象从Javascript发布到Servlet

我试图通过AJAX将JSON对象发布到servlet。但是，该对象在servlet中为null。我无法找出这段代码的错误

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");

---

如果您想将数据作为参数接收，则必须将其作为

application/x-www-form-urlencode

发送

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

---

非常感谢。我为此挣扎了很久。它只是工作得很好。