How to read json sent by ajax in servlet

Question

I'm new to java and I struggling with this problem for 2 days and finally decided to ask here.

I am trying to read data sent by jQuery so i can use it in my servlet

jQuery

var test = [     {pv: 1000, bv: 2000, mp: 3000, cp: 5000},     {pv: 2500, bv: 3500, mp: 2000, cp: 4444} ];  $.ajax({     type: 'post',     url: 'masterpaket',     dataType: 'JSON',     data: 'loadProds=1&'+test, //NB: request.getParameter("loadProds") only return 1, i need to read value of var test     success: function(data) {      },     error: function(data) {         alert('fail');     } }); 

Servlet

protected void doPost(HttpServletRequest request, HttpServletResponse response)         throws ServletException, IOException {    if (request.getParameter("loadProds") != null) {       //how do i can get the value of pv, bv, mp ,cp    } } 

I really appreciate any help you can provide.

Answer 1

You won't be able to parse it on the server unless you send it properly:

$.ajax({     type: 'get', // it's easier to read GET request parameters     url: 'masterpaket',     dataType: 'JSON',     data: {        loadProds: 1,       test: JSON.stringify(test) // look here!     },     success: function(data) {      },     error: function(data) {         alert('fail');     } }); 

You must use JSON.stringify to send your JavaScript object as JSON string.

And then on the server:

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

You can parse the json string by hand, or using any library (I would recommend gson).

Answer 2

You will have to use the JSON parser to parse the data into the Servlet

import org.json.simple.JSONObject;   // this parses the json JSONObject jObj = new JSONObject(request.getParameter("loadProds"));  Iterator it = jObj.keys(); //gets all the keys  while(it.hasNext()) {     String key = it.next(); // get key     Object o = jObj.get(key); // get value     System.out.println(key + " : " +  o); // print the key and value } 

You will need a json library (e.g Jackson) to parse the json