3. Spring Boot Validation과 Exception 예제

User.java

public class User {


    @NotEmpty
    @Size(min = 1,max = 100)
    private String name;
    @Min(1)
    @NotNull
    private Integer age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

Error.java

public class Error {

    private String field;
    private String message;
    private String invalidValue;

    public String getField() {
        return field;
    }

    public void setField(String field) {
        this.field = field;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getInvalidValue() {
        return invalidValue;
    }

    public void setInvalidValue(String invalidValue) {
        this.invalidValue = invalidValue;
    }

    @Override
    public String toString() {
        return "Error{" +
                "field='" + field + '\'' +
                ", message='" + message + '\'' +
                ", invalidValue='" + invalidValue + '\'' +
                '}';
    }
}

ErrorResponse.java

public class ErrorResponse {

    String statusCode;
    String requestUrl;
    String code;
    String message;
    String resultCode;

    List<Error> errorList;

    public String getStatusCode() {
        return statusCode;
    }

    public void setStatusCode(String statusCode) {
        this.statusCode = statusCode;
    }

    public String getRequestUrl() {
        return requestUrl;
    }

    public void setRequestUrl(String requestUrl) {
        this.requestUrl = requestUrl;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getResultCode() {
        return resultCode;
    }

    public void setResultCode(String resultCode) {
        this.resultCode = resultCode;
    }

    public List<Error> getErrorList() {
        return errorList;
    }

    public void setErrorList(List<Error> errorList) {
        this.errorList = errorList;
    }

    @Override
    public String toString() {
        return "ErrorResponse{" +
                "statusCode='" + statusCode + '\'' +
                ", requestUrl='" + requestUrl + '\'' +
                ", code='" + code + '\'' +
                ", message='" + message + '\'' +
                ", resultCode='" + resultCode + '\'' +
                ", errorList=" + errorList +
                '}';
    }
}

ApiController.java

* @validated 사용

@RestController
@RequestMapping("/api/user")
@Validated // @Validated
public class ApiController {


    /*
     * (required = false) 필수값 아님, 해당 값이 없더라도 동작하고 null값 지정, default는 true
     * validated 어노테이션을 사용하여 해당 GET 방식 호출시 파라미터들을 검증할 수 있음
    */
    @GetMapping("")
    public User get(
            @Size(min=2)
            @RequestParam String name,
            @NotNull
            @Min(1)
            @RequestParam Integer age){
        User user = new User();
        user.setAge(age); // NPE 발생, 500에러
        user.setName(name);

        int a = 10 + age;

        return user;
    }

    @PostMapping("")
    public User post(@Valid @RequestBody User user){
        System.out.println(user);
        return user;
    }

    // 우선순위는 컨틀롤러 ExceptionHandler가 Global 보다 우선.
    // 해당 컨틀롤러에 클라이언트가 요청시 Exception 발생한 것들중에 ExceptionHandler 존재하는 것 캐치.
//    @ExceptionHandler(value = MethodArgumentNotValidException.class)
//    public ResponseEntity MethodArgumentNotValidException(MethodArgumentNotValidException e){
//        System.out.println("ApiController @MethodArgumentNotValidException(value = MethodArgumentNotValidException.class) : ");
//        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(e.getMessage()); // 해당 에러 메시지내용 응답
//    }
}

ApiControllerAdvice.java

* 특정 클래스에 Advice 적용

//@RestControllerAdvice
@RestControllerAdvice(basePackageClasses = ApiController.class)
//@RestControllerAdvice(basePackages = "com.example.exception.controller") 해당 패키지 내 Exception 을 잡음
public class ApiControllerAdvice {


    // Exception 에러를 핸들러로 잡아서 해당 메소드 실행
    @ExceptionHandler(value = Exception.class)
    public ResponseEntity exception(Exception e){
        System.out.println("@ExceptionHandler(value = Exception.class) : ");
        System.out.println(e.getClass().getName());
        System.out.println(e.getLocalizedMessage()); // 해당 Exception 내용
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(""); // 빈 응답
    }

    @ExceptionHandler(value = MethodArgumentNotValidException.class)
    public ResponseEntity MethodArgumentNotValidException(MethodArgumentNotValidException e, HttpServletRequest httpServletRequest){
        System.out.println("@MethodArgumentNotValidException(value = MethodArgumentNotValidException.class) : ");

        List<Error> errorList = new ArrayList<>();

        BindingResult bindingResult = e.getBindingResult();
        bindingResult.getAllErrors().forEach(error->{
            FieldError field = (FieldError) error;
            String fieldName = field.getField();
            String message = field.getDefaultMessage();
            String value = field.getRejectedValue().toString();

            Error errorMsg = new Error();
            errorMsg.setField(fieldName);
            errorMsg.setMessage(message);
            errorMsg.setInvalidValue(value);

            errorList.add(errorMsg);

        });
        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setErrorList(errorList);
        errorResponse.setMessage("");
        errorResponse.setRequestUrl(httpServletRequest.getRequestURI());
        errorResponse.setStatusCode(HttpStatus.BAD_REQUEST.toString());
        errorResponse.setResultCode("FAIL");
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(errorResponse); // 해당 에러 메시지내용 응답
    }

    @ExceptionHandler(value = ConstraintViolationException.class)
    public ResponseEntity ConstraintViolationException(ConstraintViolationException e, HttpServletRequest httpServletRequest){
        System.out.println("@ConstraintViolationException(value = ConstraintViolationException.class) : ");

        List<Error> errorList = new ArrayList<>();

        // e.getConstraintViolations() 에러 정보
        e.getConstraintViolations().forEach(error ->{
            Stream<Path.Node> stream = StreamSupport.stream(error.getPropertyPath().spliterator(), false);
            List<Path.Node> list = stream.collect(Collectors.toList());

            String field = list.get(list.size()-1).getName();
            String message = error.getMessage();
            String invalidValue = error.getInvalidValue().toString();

            Error errorMsg = new Error();
            errorMsg.setField(field);
            errorMsg.setMessage(message);
            errorMsg.setInvalidValue(invalidValue);

            errorList.add(errorMsg);

        });
        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setErrorList(errorList);
        errorResponse.setMessage("");
        errorResponse.setRequestUrl(httpServletRequest.getRequestURI());
        errorResponse.setStatusCode(HttpStatus.BAD_REQUEST.toString());
        errorResponse.setResultCode("FAIL");
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(errorResponse); // 해당 에러 메시지내용 응답
    }

    @ExceptionHandler(value = MissingServletRequestParameterException.class)
    public ResponseEntity MissingServletRequestParameterException(MissingServletRequestParameterException e, HttpServletRequest httpServletRequest){
        System.out.println("@MissingServletRequestParameterException(value = MissingServletRequestParameterException.class) : ");
        List<Error> errorList = new ArrayList<>();

        String fieldName = e.getParameterName();
        String value = e.getMessage();

        Error errorMsg = new Error();
        errorMsg.setField(fieldName);
        errorMsg.setInvalidValue(value);

        errorList.add(errorMsg);
        ErrorResponse errorResponse = new ErrorResponse();
        errorResponse.setErrorList(errorList);
        errorResponse.setMessage("");
        errorResponse.setRequestUrl(httpServletRequest.getRequestURI());
        errorResponse.setStatusCode(HttpStatus.BAD_REQUEST.toString());
        errorResponse.setResultCode("FAIL");
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(errorResponse); // 해당 에러 메시지내용 응답
    }
}

HTTP 요청 BODY

{
  "name":"",
  "age":0
}

HTTP 응답 BODY

{
"statusCode": "400 BAD_REQUEST",
"requestUrl": "/api/user",
"code": null,
"message": "",
"resultCode": "FAIL",
"errorList":[
{
"field": "name",
"message": "크기가 1에서 100 사이여야 합니다",
"invalidValue": ""
},
{
"field": "name",
"message": "비어 있을 수 없습니다",
"invalidValue": ""
},
{
"field": "age",
"message": "1 이상이어야 합니다",
"invalidValue": "0"
}
]
}