/// <summary>
    /// 中間件定義和業(yè)務(wù)邏輯
    /// </summary>
    public class MyMiddleware
    {
        private readonly RequestDelegate _next;
        /// <summary>
        /// 構(gòu)造
        /// </summary>
        /// <param name="next"></param>
        public MyMiddleware(RequestDelegate next)
        {
            _next = next;
        }
        /// <summary>
        /// 方法名必須命名為 Invoke或者 InvokeAsync,才能有效執(zhí)行下一個(gè)中間件
        /// </summary>
        /// <param name="httpContext"></param>
        /// <returns></returns>
        public async Task InvokeAsync(HttpContext httpContext)
        {
            /*
             * 在這里可以書(shū)寫(xiě)業(yè)務(wù)處理邏輯
             *中間件的處理流程就像一個(gè)俄羅斯套娃，微軟約定中間件需要兩個(gè)參數(shù)，一個(gè)是httpcontext上下文對(duì)象，一個(gè)是Task類(lèi)型的委托。
             * 通過(guò)上下文對(duì)象，處理請(qǐng)求，通過(guò)委托傳遞上下文對(duì)象到下一個(gè)中間件（這也是套娃模式的由來(lái)）。
             */
            try
            {
                await _next(httpContext);
            }
            catch (Exception ex)
            {
                //內(nèi)部出現(xiàn)異常
                httpContext.Response.StatusCode = 500;
            }
            finally
            {
                var statusCode = httpContext.Response.StatusCode;
                var msg = "";
                switch (statusCode)
                {
                    case 401:
                        msg = "未授權(quán)";
                        break;
                    case 403:
                        msg = "拒絕訪問(wèn)";
                        break;
                    case 404:
                        msg = "未找到服務(wù)";
                        break;
                    case 405:
                        msg = "405 Method Not Allowed";
                        break;
                    case 500:
                        msg = "服務(wù)器內(nèi)部錯(cuò)誤";
                        break;
                    case 502:
                        msg = "請(qǐng)求錯(cuò)誤";
                        break;
                }
                if (!string.IsNullOrWhiteSpace(msg))
                {
                    await HandleExceptionAsync(httpContext, msg);
                }
            }
        }
        /// <summary>
        /// 處理Http響應(yīng)異常
        /// </summary>
        /// <param name="httpContext"></param>
        /// <param name="msg"></param>
        /// <returns></returns>
        private async Task HandleExceptionAsync(HttpContext httpContext, string msg)
        {
            ErrorModel error = new ErrorModel
            {
                code = httpContext.Response.StatusCode,
                msg = msg
            };
            var result = JsonConvert.SerializeObject(error);
            httpContext.Response.ContentType = "application/json;charset=utf-8";
            await httpContext.Response.WriteAsync(result).ConfigureAwait(false);
        }
    }

/// <summary>
    /// 中間件拓展類(lèi)
    /// </summary>
    public static  class MyMiddlewareExtensions
    {
        /// <summary>
        /// 將封裝的中間件委托到一個(gè)類(lèi)中，通過(guò)IApplicationBuilder拓展方法暴露
        /// </summary>
        /// <param name="builder"></param>
        /// <returns></returns>
        public static IApplicationBuilder UseMyMiddlewareOne(this IApplicationBuilder builder)
        {
            return builder.UseMiddleware<MyMiddleware>();
        }
        /*
         * 下面還可以拓展其他自定義中間件方法，通過(guò)IApplicationBuilder暴露
         */
    }

 // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                //開(kāi)發(fā)環(huán)境使用
                app.UseSwagger();
                app.UseSwaggerUI(option =>
                {
                    foreach (string version in typeof(ApiVersions).GetEnumNames())
                    {
                        option.SwaggerEndpoint($"/swagger/{version}/swagger.json", $"版本：{version}");
                    }
                });
            }
            app.UseRouting();
            //使用自定義中間件：
            app.UseMyMiddlewareOne();//注冊(cè)自定義中間件
            app.UseAuthorization();
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }

    /// <summary>
        /// 自定義中間件測(cè)試
        /// </summary>
        /// <param name="param"></param>
        /// <returns></returns>
        [HttpGet]
        public int  MiddleWareTest(string param)
        {
            /*
             * note:此處的字符串是否是數(shù)字不做判斷，當(dāng)輸入的非數(shù)字字符串時(shí)，強(qiáng)轉(zhuǎn)Int服務(wù)內(nèi)部會(huì)
             */
            int Number = int.Parse(param);
            return Number;
        }