Spring Boot 自定义异常类

自定义异常类封装业务错误信息，配合全局异常处理实现精准的错误响应。

设计原则

• 继承RuntimeException（非受检异常）
• 包含错误码和错误信息
• 支持链式异常

基本实现

public class BusinessException extends RuntimeException {

    private final int code;
    private final String message;

    public BusinessException(int code, String message) {
        super(message);
        this.code = code;
        this.message = message;
    }

    public BusinessException(ErrorCode errorCode) {
        super(errorCode.getMessage());
        this.code = errorCode.getCode();
        this.message = errorCode.getMessage();
    }

    public int getCode() {
        return code;
    }

    @Override
    public String getMessage() {
        return message;
    }
}

错误码枚举

public enum ErrorCode {

    USER_NOT_FOUND(1001, "用户不存在"),
    USER_EXISTS(1002, "用户已存在"),
    INVALID_PARAMETER(2001, "参数错误"),
    UNAUTHORIZED(3001, "未授权"),
    FORBIDDEN(3002, "禁止访问");

    private final int code;
    private final String message;

    ErrorCode(int code, String message) {
        this.code = code;
        this.message = message;
    }

    public int getCode() { return code; }
    public String getMessage() { return message; }
}

异常类层级设计

// 基础业务异常
public class BusinessException extends RuntimeException { ... }

// 参数异常
public class ParameterException extends BusinessException {
    public ParameterException(String message) {
        super(ErrorCode.INVALID_PARAMETER.getCode(), message);
    }
}

// 资源不存在异常
public class NotFoundException extends BusinessException {
    public NotFoundException(String message) {
        super(ErrorCode.USER_NOT_FOUND.getCode(), message);
    }
}

全局异常处理集成

@RestControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(BusinessException.class)
    public ResponseEntity<Result> handleBusinessException(BusinessException e) {
        return ResponseEntity.ok(Result.fail(e.getCode(), e.getMessage()));
    }

    @ExceptionHandler(NotFoundException.class)
    public ResponseEntity<Result> handleNotFound(NotFoundException e) {
        return ResponseEntity.status(404).body(Result.fail(e.getCode(), e.getMessage()));
    }
}

使用示例

@Service
public class UserService {

    public User getById(Long id) {
        User user = userRepository.findById(id);
        if (user == null) {
            throw new NotFoundException("用户不存在: " + id);
        }
        return user;
    }

    public void createUser(UserDTO dto) {
        if (userRepository.existsByUsername(dto.getUsername())) {
            throw new BusinessException(ErrorCode.USER_EXISTS);
        }
        // ...
    }
}

要点总结

• 自定义异常继承RuntimeException
• 使用枚举统一管理错误码
• 按业务领域设计异常类层级
• 配合全局异常处理返回统一响应