본문으로 건너뛰기
spring

SpringBoot Exception 처리하기

Paul Lee··약 4분 읽기
  • SpringBoot를 사용해서 개발을 하다보면 Exception 처리를 해야하는 경우가 생긴다. 해당하는 경우에 어떻게 예외처리하면 좋은지, 어떤 방법들이 있는지 한번 정리해보고자 한다
  • When developing with SpringBoot, there are cases where you need to handle exceptions. I want to organize how to handle exceptions and what methods are available in such cases.

Exception 처리하기​

  • 컨트롤러에 Excpetion을 하나씩 붙여나가면서 작업을 해 보자

Handling Exceptions​

  • Let's work by adding exceptions one by one to the controller.

기본 Controller와 Return 객체 만들기​

  • 기본 컨트롤러를 하나 만들고, 컨트롤러의 Response에 담아 줄 객체를 만들어 보자
  • 컨트롤러와 객체는 아래와 같이 만들어주었다

Creating a Basic Controller and Return Object​

  • Let's create a basic controller and an object to be included in the controller's response.
  • The controller and object were created as follows:
// 컨트롤러 클래스
package com.example.springcontrolleradvice.controller;

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/orders")
public class OrderController {

    @GetMapping("/{orderId}")
    public ResponseEntity<CommonResponse> getOrder(@PathVariable String orderId) {
        return ResponseEntity.ok(new CommonResponse("success", "order found", orderId));
    }
}

  • /orders/{orderId}로 GET 요청을 보내면, orderId를 Response에 담아서 보내준다
  • When you send a GET request to /orders/{orderId}, it returns the orderId in the response.
// 컨트롤러의 Response 객체
package com.example.springcontrolleradvice.controller;

public record CommonResponse(
String Status,
String message,
Object data
) {}

Exception 붙이기​

  • 컨트롤러에서 orderId가 100이 아닌 경우에는 Exception을 발생시켜보자

Adding Exception​

  • Let's throw an exception when orderId is not 100 in the controller.
package com.example.springcontrolleradvice.controller;


import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/orders")
public class OrderController {

    @GetMapping("/{orderId}")
    public ResponseEntity<CommonResponse> getOrder(@PathVariable String orderId) throws Exception {
        if(!orderId.equals("100")){
            throw new Exception("order not found");
        }
        return ResponseEntity.ok(new CommonResponse("success", "order found", orderId));
    }

}

  • 위처럼 Exception을 적용시키면, orderID가 100이 아닌경우에는 Exception 이 로그에 나온다
  • When you apply an exception like above, if orderID is not 100, the exception will appear in the logs.

Custom Exception 만들기​

  • 발생하는 Exception을 상속받아 CustomException을 만들어보자

Creating Custom Exception​

  • Let's create a CustomException by extending the Exception class.
package com.example.springcontrolleradvice.controller.exception;

public class CustomException extends RuntimeException {
    private String message;
    private String errorCode;
    private String hint;

    protected CustomException() {
    }

    public CustomException(String message, String errorCode, String hint) {
        this.message = message;
        this.errorCode = errorCode;
        this.hint = hint;
    }

    // getters and setters
}

컨트롤러에 CustomException을 적용하자​

Applying CustomException to the Controller​

package com.example.springcontrolleradvice.controller;

import com.example.springcontrolleradvice.controller.exception.CustomException;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
RequestMapping("/orders")

public class OrderController {

    @GetMapping("/{orderId}")
    public ResponseEntity<CommonResponse> getOrder(@PathVariable String orderId) {
        if (!orderId.equals("100")) {
            throw new CustomException("order not found", "ERROR400", "please check the order id");
        }
        return ResponseEntity.ok(new CommonResponse("success", "order found", orderId));
    }

}
  • CustomException을 적용시키면, Exception이 발생했을 때, CustomException이 발생한다
  • When you apply CustomException, the CustomException will be thrown when an exception occurs.

CustomException을 처리하는 Handler 만들기​

  • 위의 과정은 Exception 발생시 Exception만 발생한다. 우리가 원하는 CustomException 메시지는 return되지 않는다.
  • Exception을 발생시킬 때, 리턴되는 메시지에 우리의 CustomException을 넣어주도록 하자
  • Exception을 intercept 해 주는 곳을 만들어서 우리의 CustomException을 return하도록 하자
  • CustomExceptionInterceptor를 작성하자

Creating a Handler to Process CustomException​

  • The above process only throws an exception when an exception occurs. The CustomException message we want is not returned.
  • Let's include our CustomException in the returned message when an exception is thrown.
  • Let's create a place to intercept the exception and return our CustomException.
  • Let's write CustomExceptionInterceptor.
package com.example.springcontrolleradvice.controller.exception;


import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

@ControllerAdvice
public class CustomExceptionInterceptor extends ResponseEntityExceptionHandler {

    @ExceptionHandler(CustomException.class)
    public final ResponseEntity<Object> handleCustomException(CustomException ex) {
        CustomExceptionModel exceptionResponse = new CustomExceptionModel(ex.getMessage(), ex.getErrorCode(), ex.getHint());
        return new ResponseEntity(exceptionResponse, HttpStatus.INTERNAL_SERVER_ERROR);
    }
}
  • @ControllerAdvice를 사용해서 Exception을 intercept 해주는 곳을 만들어준다
  • ResponseEntityExceptionHandler를 상속받아 CustomeExceptionInterceptor가 Exception이 발생 할 때 가로 채 주도록 만들자
  • CustomExceptionModel은 CustomException과 동일한 구조를 가지고있는 메시지객체로 작성 해준다
  • Use @ControllerAdvice to create a place that intercepts exceptions.
  • Extend ResponseEntityExceptionHandler to make CustomExceptionInterceptor intercept when an exception occurs.
  • Write CustomExceptionModel as a message object with the same structure as CustomException.
package com.example.springcontrolleradvice.controller.exception;

public record CustomExceptionModel(
        String message,
        String errorCode,
        String hint
) {
}
  • 우리가 작성한 메시지로 exception을 return 해준다
  • It returns the exception with the message we wrote.