How to reuse customized response in spring boot

Question

I wrote an simple api by spring boot.
And when save is success, it response with 200 httpStatus code that I made by json type.
But I want to use this response globally reusing it.

@PostMapping("/notice")
public ResponseEntity<Object> createNotice(@RequestBody @Valid NoticeDto noticeDto, HttpServletResponse response) {
    noticeService.createNotice(noticeDto);


    ObjectNode jsonResponse = null;
    try {
        ObjectMapper mapper = new ObjectMapper();

        jsonResponse = mapper.createObjectNode();
        jsonResponse.put("code", 200);
        jsonResponse.put("success", true);
        jsonResponse.put("msg", "OK");
    } catch (Exception ex) {
        ex.printStackTrace();
    }

    PrintWriter out = response.getWriter();
    response.setStatus(200);
    response.setContentType("application/json");
    response.setCharacterEncoding("UTF-8");
    out.flush();

}

For example, I want to use it like this.

@PostMapping("/notice")
public ResponseEntity<Object> createNotice(@RequestBody @Valid NoticeDto noticeDto, HttpServletResponse response) {
    noticeService.createNotice(noticeDto);
    
    return successResponse something...
}

For this purpose, which class file should I write?
Thank you for reading my questiong.

Answer 1

You can change the controller method this way:

You can achieve this in multiple ways. One of the way is as mentioned below.

package com.example.demo.controller;

import com.example.demo.dto.NoticeDto;
import com.example.demo.service.NoticeService;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import java.util.Map;

@RestController
public class DemoController {

    @Autowired(required = false)
    private NoticeService noticeService;

    @PostMapping(value = "/notice", produces = "application/json", 
   consumes="application/json")
public ResponseEntity<Map> createNotice(@RequestBody NoticeDto noticeDto) { //
    noticeService.createNotice(noticeDto);

    ObjectNode jsonResponse = null;
    try {
        ObjectMapper mapper = new ObjectMapper();

        jsonResponse = mapper.createObjectNode();
        jsonResponse.put("code", 200);
        jsonResponse.put("success", true);
        jsonResponse.put("msg", "OK");
    } catch (Exception ex) {
        ex.printStackTrace();
    }

    return new SuccessResponseWrapper<String>(jsonResponse.toPrettyString()).build();

}

}

And

You can add a new class called SuccessResponseWrapper.

package com.example.demo.controller;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.util.MultiValueMap;

public class SuccessResponseWrapper<T> {

private ResponseEntity<T> responseEntity;

public SuccessResponseWrapper(T body) {
    HttpStatus status = HttpStatus.OK;
    responseEntity = new ResponseEntity<>(body, status);
}

public SuccessResponseWrapper(MultiValueMap<String, String> headers) {
    HttpStatus status = HttpStatus.OK;
    responseEntity = new ResponseEntity<>(headers, status);
}

public SuccessResponseWrapper(T body, MultiValueMap<String, String> headers) {
    HttpStatus status = HttpStatus.OK;
    responseEntity = new ResponseEntity<>(body, headers, status);
}

public SuccessResponseWrapper(T body, MultiValueMap<String, String> headers, int rawStatus) {
    responseEntity = new ResponseEntity<>(body, headers, 200);
}

    public ResponseEntity build() {
         return this.responseEntity;
    }
}

In this way, you can reuse the SuccessResponseWrapper with Predefined http response code 200.

Answer 2

You can do something like this

class HttpResponsePrinter{
  public static  void ok(HttpServletResponse response){
      write(response, 200, 200, true, "OK");
  }
  private static void write(HttpServletResponse response,int httpCode, int code, bool success, String message) {
    ObjectNode jsonResponse = null;
    try {
        // you can reuse object mapper as well
        ObjectMapper mapper = new ObjectMapper();
        jsonResponse = mapper.createObjectNode();
        jsonResponse.put("code", code);
        jsonResponse.put("success", success);
        jsonResponse.put("msg", message);
      } catch (Exception ex) {
        ex.printStackTrace();
     }
     PrintWriter out = response.getWriter();
     response.setStatus(httpCode);
     response.setContentType("application/json");
     response.setCharacterEncoding("UTF-8");
     out.flush();
  }
}

Usage:

@PostMapping("/notice")
public ResponseEntity<Object> createNotice(@RequestBody @Valid NoticeDto noticeDto, HttpServletResponse response) {
    noticeService.createNotice(noticeDto);
    HttpResponsePrinter.ok(response);
}