C# Webapi异常处理

增加异常拦截处理

        public static void Register(HttpConfiguration config)
        {
            // Web API 配置和服务

            // Web API 路由  routeTemplate: "api/{controller}/{id}",
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{action}/{id}",
               
                defaults: new { id = RouteParameter.Optional }
            );

            //自定义异常拦截器, 统一解析
            config.Filters.Add(new CustomAttributes.CustomExceptionFilter());

            //自定义错误消息处理委托类
            config.MessageHandlers.Add(new CustomAttributes.CustomErrorMessageDelegatingHandler());
        }

CustomExceptionFilter

    /// <summary>
    /// CustomExceptionFilter
    /// </summary>
    public class CustomExceptionFilter : ExceptionFilterAttribute
    {
        /// <summary>
        /// OnException
        /// </summary>
        /// <param name="actionExecutedContext"></param>
        public override void OnException(HttpActionExecutedContext actionExecutedContext)
        {
            ReturnT<int> robj = new ReturnT<int>();
            HttpStatusCode status = HttpStatusCode.InternalServerError;
            String message = String.Empty;
            var exception = actionExecutedContext.Exception;
            if (exception.GetType() == typeof(UnauthorizedAccessException))
            {
                message = "Access to the Web API is not authorized.";
                status = HttpStatusCode.Unauthorized;
            }
            else if (exception.GetType() == typeof(DivideByZeroException))
            {
                message = "Internal Server Error.";
                status = HttpStatusCode.InternalServerError;
            }
            else
            {
                message = exception.Message;
                status = HttpStatusCode.InternalServerError;
            }
            robj.Result = (int)status;
            robj.ErrorMessage = message;
            robj.ExeResult = false;
            actionExecutedContext.Response = new HttpResponseMessage()
            {
                Content = new StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(robj), System.Text.Encoding.UTF8, "application/json"),
                StatusCode = status
            };
            base.OnException(actionExecutedContext);
        }
    }

CustomErrorMessageDelegatingHandler

    /// <summary>
    /// API自定义错误消息处理委托类。用于处理访问不到对应API地址的情况，对错误进行自定义操作。 
    /// </summary>
    public class CustomErrorMessageDelegatingHandler : DelegatingHandler
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="request"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            return base.SendAsync(request, cancellationToken).ContinueWith<HttpResponseMessage>((responseToCompleteTask) => {
                HttpResponseMessage response = responseToCompleteTask.Result;
                HttpError error = null;
                ReturnT<int> robj = new ReturnT<int>();
                if (response.TryGetContentValue<HttpError>(out error))
                { //添加自定义错误处理 //error.Message = "Your Customized Error Message";
                    
                }
                if (error != null)
                {
                    robj.ExeResult = false;
                    robj.ErrorMessage = error.Message;
                    robj.Result = (int)response.StatusCode;
                    //获取抛出自定义异常，有拦截器统一解析
                    throw new HttpResponseException(new HttpResponseMessage(response.StatusCode)
                    { 
                        Content = new StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(robj), System.Text.Encoding.UTF8, "application/json"),
                        ReasonPhrase = "Exception"
                    });
                }
                else { return response; }
            });
        }
    }