秒杀第六节：定义通用的返回对象-返回错误信息

新建package文件error。新建CommonError对象

public interface CommonError {

    public int getErrCode();
    public String getErrMsg();
    public CommonError setErrMsg(String errMsg);
}

新建EmBusinessError implements CommonError

public enum EmBusinessError implements CommonError {

    //通用错误类型100001
    PARAMETER_VALIDATION_ERROR(10001,"参数不合法"),
    UNKNOW_ERROR(10002,"未知错误"),
    //2000开头为用户相关错误
    USER_NOT_EXIST(20001,"用户不存在"),
    USER_LOGIN_FAIL(20002,"手机或密码不存在"),
    USER_NOT_LOGIN(20003,"用户还未登陆"),
    //30000开头为交易型错误
    STOCK_NOT_ENOUGH(30001,"库存不足")
    ;

    private int errCode;
    private String errMsg;

    private EmBusinessError(int errCode,String errMsg){
        this.errCode = errCode;
        this.errMsg = errMsg;
    }

    @Override
    public int getErrCode() {
        return this.errCode;
    }

    @Override
    public String getErrMsg() {
        return this.errMsg;
    }

    //改动通用错误的errMsg
    @Override
    public CommonError setErrMsg(String errMsg) {
        this.errMsg = errMsg;
        return this;
    }
}

新建BussinessException extends Exception implements CommonError

//包装器业务异常类实现
public class BussinessException extends Exception implements CommonError {
    //emun
    private CommonError commonError;

    //直接接收EmBusinessError的传参用于构造业务异常
    public BussinessException(CommonError commonError){
        super();
        this.commonError = commonError;
    }

    //接收自定义errMsg的方式构造业务异常（通过覆盖原本errMsg）
    public BussinessException(CommonError commonError,String errMsg) {
        super();
        this.commonError = commonError;
        this.commonError.setErrMsg(errMsg);
    }


    @Override
    public int getErrCode() {
        return this.commonError.getErrCode();
    }

    @Override
    public String getErrMsg() {
        return this.commonError.getErrMsg();
    }

    @Override
    public CommonError setErrMsg(String str) {
        this.commonError.setErrMsg(str);
        return this;
    }
}

优化controller代码，增加错误信息处理

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/get")
    public CommonReturnType getUser(@RequestParam(name = "id") Integer id) throws BussinessException {
        //调用service服务获取对应id对象返回给前端
        UserModel userModel = userService.getUserById(id);
        //若获取的对应用户信息存在
        if (userModel == null) {
//            userModel.setEncrptPassword("123");
            throw new BussinessException(EmBusinessError.USER_NOT_EXIST);
        }

        //将核心领域模型用户对象转换为可供UI使用的viewobject
        UserVo userVo = convertFromMode(userModel);
        return CommonReturnType.create(userVo);
    }

    private UserVo convertFromMode(UserModel userModel) {
        if (userModel == null) {
            return null;
        }
        UserVo userVo = new UserVo();
        BeanUtils.copyProperties(userModel, userVo);
        return userVo;
    }
}

请求链接：http://localhost:8080/user/get?id=2
错误截图：

image.png
为什么返回的不是错误信息呢？因为抛出的异常没有被处理，下一节会说道异常的处理