Map<String, String> params = new HashMap<String, String>();
params.put("fromUser", "lesliefang");
params.put("toUser", "xiaojun");

JsonObjectRequest newMissRequest = new JsonObjectRequest(
    Request.Method.POST, "http://127.0.0.1:8080/users",
    new JSONObject(params), new Response.Listener<JSONObject>() {

        @Override
        public void onResponse(JSONObject jsonobj) {
             
        }
    }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
 
        }
    });