Spring boot 튜토리얼 (3) - Validation / Log / ErrorHandling

9. Validation

Validation 디펜던시 적용

/pom.xml

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-validation</artifactId>
	</dependency>

Entity

@NotBlank 적용

@Entity
public class Department {

    @Id
    @GeneratedValue(strategy =  GenerationType.AUTO)
    private Long departmentId;

    // not blank 적용
    @NotBlank(message = "Please Add Department Name")
    private String departmentName;
    private String departmentAddress;
    private String departmentCode;
    
    ...
}

Controller

@Valid 적용

@RestController
public class DepartmentController {

    @Autowired
    private DepartmentService departmentService;

    @PostMapping("/departments")
    public Department saveDepartment(@Valid @RequestBody Department department) {
        return departmentService.saveDepartment(department);
    }
}

10. Adding Loggers in Springboot App

Logger 적용

@RestController
public class DepartmentController {

    @Autowired
    private DepartmentService departmentService;

    private final Logger LOGGER =
            LoggerFactory.getLogger(DepartmentController.class);

    @PostMapping("/departments")
    public Department saveDepartment(@Valid @RequestBody Department department) {
        LOGGER.info("Inside saveDepartment of DepartmentController");
        return departmentService.saveDepartment(department);
    }
}

결과

11. Project Lombok (Removing Boiler plate code)

Lombok이란 어노테이션 기반으로 코드를 자동완성 해주는 라이브러리이다. Lombok을 이용하면 Getter, Setter, Equlas, ToString 등과 다양한 방면의 코드를 자동완성 시킬 수 있다.

Lombok 디펜던시 및 적용

/pom.xml

    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <optional>true</optional>
    </dependency>
    
    <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <configuration>
          <excludes>
            <exclude>
              <groupId>org.projectlombok</groupId>
              <artifactId>lombok</artifactId>
            </exclude>
          </excludes>
        </configuration>
      </plugin>
    

@Entity
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Department {

    @Id
    @GeneratedValue(strategy =  GenerationType.AUTO)
    private Long departmentId;

    @NotBlank(message = "Please Add Department Name")
    private String departmentName;
    private String departmentAddress;
    private String departmentCode;

}

12. Exception Handling in Springboot

폴더 구조

1) DepartmentNotFoundException 생성

public class DepartmentNotFoundException extends Exception{
    public DepartmentNotFoundException() {
        super();
    }

    public DepartmentNotFoundException(String message) {
        super(message);
    }

    public DepartmentNotFoundException(String message, Throwable cause) {
        super(message, cause);
    }

    public DepartmentNotFoundException(Throwable cause) {
        super(cause);
    }

    protected DepartmentNotFoundException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }
}

2) ErrorMessage 생성 (lombok 적용)

@Data
@NoArgsConstructor
@AllArgsConstructor
public class ErrorMessage {

    private HttpStatus status;
    private String message;
}

3) RestResponseEntityExceptionHandler 생성

@ControllerAdvice
@ResponseStatus
public class RestResponseEntityExceptionHandler
        extends ResponseEntityExceptionHandler {

    @ExceptionHandler(DepartmentNotFoundException.class)
    public ResponseEntity<ErrorMessage> departmentNotFoundException(DepartmentNotFoundException exception,
                                                      WebRequest request) {
        ErrorMessage message = new ErrorMessage(HttpStatus.NOT_FOUND,
                exception.getMessage());

        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(message);
    }
}

(1) @ControllerAdvice : @Controller나 @RestController에서 발생한 예외를 한 곳에서 관리하고 처리할 수 있게 도와주는 어노테이션이다.
(2) @ResponseStatus : @ResponseStatus에 어노테이션을 부여하고 value에 상태 코드를 지정하면, 그 응답의 상태 코드를 지정할 수 있다.
(3) @ExceptionHandler : @ExceptionHandler같은 경우는 @Controller, @RestController가 적용된 Bean내에서 발생하는 예외를 잡아서 하나의 메서드에서 처리해주는 기능을 한다.

4) Service 적용

@Service
public class DepartmentServiceImpl implements DepartmentService {

    @Autowired
    private DepartmentRepository departmentRepository;

    @Override
    public Department fetchDepartmentById(Long departmentId) throws DepartmentNotFoundException {
        Optional<Department> department = departmentRepository.findById(departmentId);

        if(!department.isPresent()) {
            throw new DepartmentNotFoundException("Department Not Available");
        }

        return department.get();
    }
}

5) 결과

13. Changing H2 db to MySQL

1) application.properties 파일 MySql 설정

spring.jpa.hibernate.ddl-auto=update
spring.datasource.url=jdbc:mysql://localhost:3306/dcbapp
spring.datasource.username=root
spring.datasource.password=password
spring.datasource.driver-class-name =com.mysql.jdbc.Driver
spring.jpa.show-sql: true

2) Mysql 디펜던시 추가

		<dependency>
			<groupId> mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>

참고 : Spring Boot Tutorial | Full In-depth Course - Daily Code Buffer