unable to post multipart form data json request

Question

I am trying to post multipart form-data request in java to api. I am getting 400 http error code. Below is my end point in spring:

spring boot api

@org.springframework.web.bind.annotation.PostMapping(value="register2")
public ResponseEntity<CoreResponseHandler> doRegister2(@RequestPart String json)  { 
System.out.println("~~~~~~     "+json+"   ~~~~~~"); 
    return null;
}

core java code to consume above api

  import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import org.json.JSONException;
import org.json.JSONObject;
public class Test {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://localhost:8012/register2");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW");
            conn.setRequestProperty("charset","utf-8");
            conn.setRequestProperty("Content-Disposition","form-data;name='json'");
            conn.setDoOutput(true);
            conn.setDoInput(true);
            JSONObject jsonObject = buidJsonObject();
            setPostRequestContent(conn, jsonObject);
            conn.connect();
            System.out.println(conn.getResponseCode());
            if(conn.getResponseCode()==200){
                BufferedReader reader= new BufferedReader(new InputStreamReader(conn.getInputStream()));
                StringBuilder stringBuilder = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null)
                {
                    stringBuilder.append(line + "\n");
                }
                System.out.println(stringBuilder+" <<<<<<<<<<<<<<<<<<<<<<<<<" );
                jsonObject=new JSONObject(stringBuilder.toString());    
            }
            else{
                BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getErrorStream()));
                StringBuilder stringBuilder = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null)
                {
                    stringBuilder.append(line + "\n");
                }
                System.out.println(stringBuilder+" <<<<<<<<<<<<<<<<<<<<<<<<<" );
                System.out.println("ERRORERRORERRORERRORERRORERRORERRORERRORERROR"+conn.getResponseCode());
            }

        }catch(Exception ex) {
            ex.printStackTrace();
        }

    }

    private static  JSONObject buidJsonObject() throws JSONException {

        JSONObject jsonObject = new JSONObject();
        jsonObject.accumulate("username", "13338912");
        jsonObject.accumulate("encryptedPassword", "encpass");
        jsonObject.accumulate("name",  "fish");
        jsonObject.accumulate("email",  "fish@fish.com");
        jsonObject.accumulate("status",  "active");


        return jsonObject;
    }

    private static void setPostRequestContent(HttpURLConnection conn, 
            JSONObject jsonObject) throws IOException {

        OutputStream os = conn.getOutputStream();
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
        writer.write(jsonObject.toString());
        writer.flush();
        writer.close();
        os.close();
    }

}

below is the output that I got:

output

400

Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Tue Oct 09 13:51:00 IST 2018There was an unexpected error (type=Bad Request, status=400).Required request part 'json' is not present <<<<<<<<<<<<<<<<<<<<<<<<< ERRORERRORERRORERRORERRORERRORERRORERRORERROR400

I don't want to use 3rd party dependencies like okkhttp etc.

where is my logic wrong. kindly correct me. Why am I not getting http status 200

~~~~~~~~~~~~~problem seems to be unsolvable~~~~~~~~~~~~~

Answer 1

@org.springframework.web.bind.annotation.PostMapping(value="register2" ,consumes = MediaType.APPLICATION_JSON, 
                produces = MediaType.APPLICATION_JSON)
public ResponseEntity<CoreResponseHandler> doRegister2(@RequestPart String json)  { 
System.out.println("~~~~~~     "+json+"   ~~~~~~"); 
    return null;
}

It's also a solution please try this one