How to read the data in request body of XMLHTTP POST request in servlet

Question

JS Function:

function loadAjax1(y){
            var r=document.getElementById(y);
            var id=r.children[0].value;
            var name=r.children[1].value;
            var location=r.children[2].value;
            var nbed=r.children[3].value;
            var obed=r.children[4].value;
            var ibed=r.children[5].value;


            
            
            var url="Ajax";
            
            var data = `{
               "data":[
                  {
                     "type":"hospitals",
                     "id":"12",
                     "attributes":{
                        "hid":"113",
                        "hospital_name":"RKO",
                        "location":"DEF",
                        "normal_beds":"9",
                        "oxygen_beds":"10",
                        "icu_beds":"12"
                     }
                  }
                 ]
            }`;
            
            console.log(data);

            if(window.XMLHttpRequest){
                
                request = new XMLHttpRequest();
                
            }else if(window.ActiveXObject){
                
                request = new ActiveXObject("Microsoft.XMLHTTP");
            }
            
            try{
                request.onreadystatechange=sendInfo1;
                request.open("POST",url,true);
                request.setRequestHeader("Content-Type", "application/vnd.api+json");
                request.send(JSON.stringify(data));
                
            }catch(e){
                alert("Unable to connect server");
            }
            
        }

This is my code for AJAX call. Here I am making a POST request with XMLHTTP request object and this request is sent to a servlet. How can I read the request body in the servlet? I have tried with request.getParameter(). But it is not working and it says that the string is null. How can I fetch the data in request body and PARSE it as JSON.

Thanks in Advance