Golang接口响应封装与错误处理技巧

type Response struct {
    Code    int         `json:"code"`
    Message string      `json:"message"`
    Data    interface{} `json:"data,omitempty"`
}

<code>func Success(data interface{}) *Response {
    return &Response{
        Code:    0,
        Message: "success",
        Data:    data,
    }
}

func Error(code int, message string) *Response {
    return &Response{
        Code:    code,
        Message: message,
    }
}</code>

const (
    ErrCodeInvalidParam = 4001
    ErrCodeUnauthorized = 4002
    ErrCodeServerInternal = 5001
)

var (
    ErrInvalidParam = errors.New("invalid parameter")
    ErrUnauthorized = errors.New("unauthorized")
)

func Recovery() gin.HandlerFunc {
    return func(c *gin.Context) {
        defer func() {
            if err := recover(); err != nil {
                log.Printf("panic: %v\n", err)
                c.JSON(500, Error(ErrCodeServerInternal, "internal error"))
                c.Abort()
            }
        }()
        c.Next()
    }
}

func HandleAppError(err error) *Response {
    switch {
    case errors.Is(err, ErrInvalidParam):
        return Error(ErrCodeInvalidParam, "参数错误")
    case errors.Is(err, ErrUnauthorized):
        return Error(ErrCodeUnauthorized, "未授权")
    default:
        log.Println("unexpected error:", err)
        return Error(ErrCodeServerInternal, "系统异常")
    }
}

func GetUser(c *gin.Context) {
    id := c.Param("id")
    if id == "" {
        c.JSON(400, Error(ErrCodeInvalidParam, "ID 不能为空"))
        return
    }

    user, err := userService.FindByID(id)
    if err != nil {
        if errors.Is(err, ErrUserNotFound) {
            c.JSON(404, Error(4040, "用户不存在"))
        } else {
            c.JSON(500, HandleAppError(err))
        }
        return
    }

    c.JSON(200, Success(user))
}