javascript - HttpServletRequest can not get xhr request parameter -

i working spring , javascript. calling @controller xhrhttprequest object.

i can see parameter(json string) chrome inspector, when call request.getparamter("id") returns null.

calling part js function ajax(url, data, callback, method){     //data {"id":"system", "password" : "1234"}     var httprequest;     var afteraction = function(){         if(!httprequest) {             console.error('can not find httprequest variable');             return;         }          if (httprequest.readystate === xmlhttprequest.done) {             if (httprequest.status === 200) {                 var responsedata = httprequest.responsetext;                 //alert(json.stringify(responsedata));                 console.log('result of api call >>>', responsedata);                 if(typeof callback == 'function') {                     callback(json.parse(responsedata));                 }             } else {                 alert('there problem request.');             }         }     }      //=========== logic ============     if (window.xmlhttprequest) { // mozilla, safari, ie7+ ...         httprequest = new xmlhttprequest();     } else if (window.activexobject) { // ie 6 , older         httprequest = new activexobject('microsoft.xmlhttp');     }      if(!method) method = 'post';     data = (!!data) ? json.stringify(data) : '';      httprequest.onreadystatechange = afteraction;     httprequest.open(method.touppercase(), url, true);     httprequest.setrequestheader("content-type", "application/json; charset=utf-8");     //httprequest.setrequestheader("content-length", data.length);     //httprequest.setrequestheader("connection", "close");     httprequest.send(data); } 

receive part spring @controller

@controller @requestmapping(value={"member"}, produces={"application/json"}) @responsestatus(value = httpstatus.ok) public class membercontroller {      /**      * @param request      * @param resp      * @return      * @throws exception      */     @requestmapping(value={"/login"})     public @responsebody string login(httpservletrequest request, httpservletresponse resp) throws exception {         system.out.println("login request");         string id = string.valueof(request.getparameter("id"));                 //returns null         string password = string.valueof(request.getparameter("password"));     //returns null          map<string, string> result = new hashmap<string, string>();         result.put("result", "s");         result.put("message", "login success");         objectmapper mapper = new objectmapper();         return mapper.writevalueasstring(result);     } } 

i not know why parameter becomes null. thanks.

you need follow below steps accept json in controller:

(1) define userlogin bean hold json

public class userlogin  {     private string id;     private string password;      //add getters , setters } 

(2) change controller accept json & receive userlogin bean

@controller @requestmapping(value={"member"}, produces={"application/json"}) @responsestatus(value = httpstatus.ok) public class membercontroller {      @requestmapping(value={"/login"}, method = requestmethod.post, consumes = mediatype.application_json_value)     public @responsebody string login(userlogin userlogin) throws exception {         system.out.println("login request");         string id = userlogin.getid();                     string password = userlogin.getpassword();          map<string, string> result = new hashmap<string, string>();         result.put("result", "s");         result.put("message", "login success");         objectmapper mapper = new objectmapper();         return mapper.writevalueasstring(result);     } }