HttpServletRequest in spring getting parameters values as null for post request - spring

Question

#ResponseBody
#RequestMapping(value = {"apiRequest"}, method = {RequestMethod.POST})
public String contestApiSignUp(HttpServletRequest req) throws JSONException {
try {
String username = req.getParameter("username");
String firstname = req.getParameter("firstname");
String lastname = req.getParameter("lastname");
String password = req.getParameter("password");
String phone = req.getParameter("phone");
Here the values I am getting all are null. That is username =null, firstname =null...
I am hitting post request with the values
http://localhost:8080/apiRequest.htm
username = Subhajit
firstname = Subha
...
like this.
But while I am using same code but,
#RequestMapping(value = {"apiRequest"}, method = {RequestMethod.GET})
using GET instead of POST then I am getting the proper values.

Answer 1

When you sent your HTML Form by POST to your URL /apiRequest, did you fill your data (username, firstname etc.) in fields in your form, or did you attached them to the sent URL (eg. apiRequest.htm?username=test&...) ?
Because with the second approach, you data will be accessible only through a GET request, not a POST. The first approach will work with a POST request.
Also, you do not need to call explicitly getParameter on the HttpServletRequest in a Spring Controller.
You can do this :
#ResponseBody
#RequestMapping (value = "apiRequest", method = RequestMethod.POST)
public String contestApiSignUp(
#RequestParam ("username") String username,
#RequestParam ("firstname") String firstname,
#RequestParam ("lastname") String lastname,
#RequestParam ("password") String password,
#RequestParam ("phone") String phone) {
return "Hello World";
}

Answer 2

From the comments, you said you are trying with postman to post the request, So are you building website or webservices? either way you should not be sending your data in the headers.
If you are building a website put together an HTML file from which
you can submit a form to this controller
If you are building webservice, change the controller and let it
accept JSON (or XML -I would discourage this though) body. Follow
this https://stackoverflow.com/a/40226580/6785908. And then from
postman (or curl), post a json instead.