Spring 启动响应过滤器，用于在发送到客户端之前重组 controller 响应

Question

I have a couple of spring boot rest controllers, and I want a standard JSON response structure to be sent to the client.

The standard response will be composed of responseTime, apiResponseCode, status, apiName, response ( which will vary based on the api). See below:

{
"responseTime": "2020-04-19T08:36:53.001",
"responseStatus": "SUCCESS",
"apiResponseCode": "SUCCESS",
"apiName": "PROPERTY_STORE_GET_PROPERTIES",
"response": [
    {
        "propertyName": "app.name",
        "propertyValue": "property-store"
    }
]
}

To achieve this, I have created below model class:

package com.example.response.model;
import java.io.Serializable;
import java.time.LocalDateTime;
import com.example.constants.ApiResponseCode;
import com.example.constants.Status;

public class ApplicationResponse<T> implements Serializable {
   private static final long serialVersionUID = -1715864978199998776L;
   LocalDateTime responseTime;
   Status responseStatus;
   ApiResponseCode apiResponseCode;
   String apiName;
   T response;

   public ApplicationResponse(LocalDateTime responseTime, Status status, 
          ApiResponseCode apiRespCode, String apiName, T response) {
    this.responseTime = responseTime;
    this.responseStatus = status;
    this.apiResponseCode = apiRespCode;
    this.apiName = apiName;
    this.response = response;
}

// getters and setters

To create a generic response wrapper, I have created below response util class.

import java.time.LocalDateTime;
import com.example.constants.ApiResponseCode;
import com.example.constants.Status;
import com.example.response.model.ApplicationResponse;

public class ResponseUtil {
    public static <T> ApplicationResponse<T> createApplicationResponse(String 
         apiName, T response) {
         return new ApplicationResponse<>(LocalDateTime.now(), 
               Status.SUCCESS, ApiResponseCode.SUCCESS, apiName,
               response);
}

private ResponseUtil() {
}
}

Now the ask is that my response from controller should get serialized in the standard way. Shown below is my controller method.

package com.example.propertystore.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.RestController;
import com.example.constants.ApiResponseCode;
import com.example.constants.Status;
import com.example.exception.ApplicationException;
import com.example.exception.ApplicationExceptionHelper;
import com.example.propertystore.constants.PropertyStoreApiName;
import com.example.propertystore.dto.PropertyDTO;
import com.example.propertystore.entity.Property;
import com.example.propertystore.service.PropertyStoreService;
import com.example.response.ResponseUtil;
import com.example.response.model.ApplicationResponse;

@RestController
public class PropertyStoreControllerImpl implements PropertyStoreController {

@Autowired
PropertyStoreService propertyStoreService;

@Autowired
ApplicationExceptionHelper exceptionHelper;

@Override
public ApplicationResponse<List<PropertyDTO>> getProperties() throws ApplicationException {
    ApplicationResponse<List<PropertyDTO>> response = null;
    try {
        response = ResponseUtil.createApplicationResponse(
            PropertyStoreApiName.PROPERTY_STORE_GET_PROPERTIES.toString(),
                propertyStoreService.getProperties());
    } catch (Exception e) {
        exceptionHelper.raiseApplicationException( HttpStatus.INTERNAL_SERVER_ERROR, Status.FAILURE,
                ApiResponseCode.INTERNAL_SERVER_ERROR,
                PropertyStoreApiName.PROPERTY_STORE_GET_PROPERTIES.toString(), null);
    }
    return response;
}}

With the current implementation what I'll have to do is that in my controllers I will have to transform the response by calling ResponseUtil.createApplicationResponse() . This is going to litter the entire controller methods with the createApplicationResponse() method call.

What I wanted to explore is that if there is any cleaner way of achieving this using servlet filters or AOP?

PS: I tried filter option, but couldn't understand how to proceed around it. Got stuck after retrieving the response.getOutputStream() in doFilter().

Hope someone can help?

Answer 1

Just wrap all your responses into a decorator object.

class ResponseDecorator<T> {
  //global.fields (time,code, status.....)
  T response;
}

Then wrap this response wrapper into the ResponseEntity

Answer 2

The response.getOutputStream that you used and filters are servlet related classes, and i think you can do that without them.Just make your custom response class and add fields however you want your response. Than in the controller, just return new ResponseEntity(HttpStatus.OK,"your message "): I don't know if this is the behavior you want.