1.自定义异常处理类

**
 * 自定义异常处理类
 * 针对不同的异常自定义不同的方法
 * 环绕通知
 * 切面:针对所有的controller中抛出的异常
 * 若使用@ControllerAdvice,则不会自动转换为JSON格式
 */
@RestControllerAdvice
public class RestExceptionHandler {

/**
 * 业务异常处理
 * @param e
 * @return ErrorInfo
 */
@ExceptionHandler({BaseBusinessException.class})
public ErrorInfo BusinessExceptionHandler(BaseBusinessException e) {
    return new ResponseResultUtil().error(e.getCode(), e.getMessage());
}

2.定义一个用于返回页面结果信息的VO对象类：ErrorInfo

public class ErrorInfo {
   private Integer code;
   private String message;

   public ErrorInfo(){};

   public ErrorInfo(Integer code, String message) {
      super();
      this.code = code;
      this.message = message;

   }
   public Integer getCode() {
      return code;
   }
   public void setCode(Integer code) {
      this.code = code;
   }
   public String getMessage() {
      return message;
   }
   public void setMessage(String message) {
      this.message = message;
   }
}
3.定义一个对步骤2中 返回信息结果处理的工具类：ResponseResultUtil

/**
 * 类名称： ResponseResultUtil <br>
 * 类描述：请求响应工具类<br>
 * 创建人：GMM <br>
 * date 2019/3/11<br>
 */
public class ResponseResultUtil {

    /**
     * @param code      响应码
     * @param message   相应信息
     * @description     请求成功返回对象
     */
    public final ErrorInfo success(int code, String message) {
        return new ErrorInfo(code, message);
    }

    /**
     * @param httpStatus  返回的响应码所对应的枚举类
     * @description         请求失败返回对象
     */
    public final ErrorInfo error(HttpStatus httpStatus) {
        return new ErrorInfo(httpStatus.value(), httpStatus.getReasonPhrase());
    }

    public final ErrorInfo error(int code, String message) {
        return new ErrorInfo(code, message);
    }
4.为方便统一管理异常代码和信息之间的关系，建立枚举类：HttpStatus 

public enum HttpStatus {
    CONTINUE(100, "Continue"),
    SWITCHING_PROTOCOLS(101, "Switching Protocols"),
    PROCESSING(102, "Processing"),
    CHECKPOINT(103, "Checkpoint"),
    OK(200, "OK"),
    CREATED(201, "Created"),
    ACCEPTED(202, "Accepted"),
    NON_AUTHORITATIVE_INFORMATION(203, "Non-Authoritative Information"),
    NO_CONTENT(204, "No Content"),
    RESET_CONTENT(205, "Reset Content"),
    PARTIAL_CONTENT(206, "Partial Content"),
    MULTI_STATUS(207, "Multi-Status"),
    ALREADY_REPORTED(208, "Already Reported"),
    IM_USED(226, "IM Used"),
    MULTIPLE_CHOICES(300, "Multiple Choices"),
    MOVED_PERMANENTLY(301, "Moved Permanently"),
    FOUND(302, "Found"),
    /** @deprecated */
    @Deprecated
    MOVED_TEMPORARILY(302, "Moved Temporarily"),
    SEE_OTHER(303, "See Other"),
    NOT_MODIFIED(304, "Not Modified"),
    /** @deprecated */
    }
5.封装一个基础业务异常类（让所有自定义业务异常类 继承此 基础类）：BaseBusinessException

/**
 * 类名称： BaseBusinessException <br>
 * 类描述： 业务异常父类<br>
 * 创建人：GMM <br>
 * date 2019/3/11<br>
 */
public class BaseBusinessException extends RuntimeException {

    private Integer code;

    // 给子类用的方法
    public BaseBusinessException(HttpStatus httpStatus) {
        this(httpStatus.value(),httpStatus.getReasonPhrase());
    }

    public BaseBusinessException(Integer code,String message) {
        super(message);
        this.code = code;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }
}
6.service 层抛出

@Service
public class UserLoginServiceImpl implements UserLoginService {

    @Autowired
    private UserLoginRepsitory userLoginRepsitory;

    @Transactional
    @Override
    public boolean login(String userCode, String password) {
        Employee employee=userLoginRepsitory.getEmployeeByCode(userCode);
        if(StringUtils.isBlank(userCode)){
            throw new BaseBusinessException(101,"用户名不能为空");
        }
}