Spring Boot 构建电商基础秒杀项目 (三) 通用的返回对象 & 异常处理

SpringBoot构建电商基础秒杀项目 学习笔记

定义通用的返回对象

public class CommonReturnType {

    // success, fail
    private String status;

    // status = success, data 内返回前端需要的 json数据
    // status = fail, data 内使用通用的错误码格式
    private Object data;

    public static CommonReturnType create(Object result){

        return create(result, "success");
    }

    public static CommonReturnType create(Object result, String status){

        CommonReturnType type = new CommonReturnType();
        type.setStatus(status);
        type.setData(result);

        return type;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }
}

定义错误接口

public interface CommonError {

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

定义错误类型枚举

public enum EmBusinessError implements CommonError {

    // 通用错误类型 10001
    PARAMETER_VALIDATION_ERROR(10001, "参数不合法"),
    UNKNOWN_ERROR(10002, "未知错误"),

    // 20000 开头为用户信息相关错误定义
    USER_NOT_EXIST(20001, "用户不存在"),

    ;

    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;
    }

    @Override
    public CommonError setErrMsg(String errMsg) {
        this.errMsg = errMsg;
        return this;
    }
}

包装器业务异常类实现

// 包装器业务异常类实现
public class BusinessException extends Exception implements CommonError {

    private CommonError commonError;

    public BusinessException(CommonError commonError){
        super();
        this.commonError = commonError;
    }

    public BusinessException(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 errMsg) {
        this.commonError.setErrMsg(errMsg);
        return this;
    }
}

定义 BaseController 处理异常

public class BaseController {

    // 定义 exceptionhandler 解决未被 controller 层吸收的 exception
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.OK)
    @ResponseBody
    public Object handlerException(HttpServletRequest request, Exception ex){

        Map<String, Object> responseData = new HashMap<>();

        if(ex instanceof BusinessException){
            BusinessException businessException = (BusinessException)ex;
            responseData.put("errCode", businessException.getErrCode());
            responseData.put("errMsg", businessException.getErrMsg());
        }else{
            responseData.put("errCode", EmBusinessError.UNKNOWN_ERROR.getErrCode());
            responseData.put("errMsg", EmBusinessError.UNKNOWN_ERROR.getErrMsg());
        }

        return CommonReturnType.create(responseData, "fail");
    }
}

修改 UserController

@Controller("user")
@RequestMapping("/user")
public class UserController extends BaseController{

    @Autowired
    private UserService userService;

    @RequestMapping("/get")
    @ResponseBody
    public CommonReturnType getUser(@RequestParam(name="id") Integer id) throws BusinessException{
        UserModel userModel = userService.getUserById(id);

        if(userModel == null){
//            userModel.setEncrptPassword("123");
            throw new BusinessException(EmBusinessError.USER_NOT_EXIST);
        }

        UserVO userVO = convertFromModel(userModel);

        return CommonReturnType.create(userVO);
    }

    private UserVO convertFromModel(UserModel userModel){
        if(userModel == null){
            return null;
        }

        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userModel, userVO);

        return userVO;
    }
}

源码：spring-boot-seckill

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