WebApi 全局使用filter

 先上代碼：

    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API 配置和服務

            // Web API 路由
            config.MapHttpAttributeRoutes();

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

            config.Filters.Add(new ApiExceptionAttribute());
        }
    }

 WebAPi的全局過濾器不同於MVC，MVC需要在FilterConfig里面添加，WebApi必須在WebApiConfig里面設置

    public class FilterConfig
    {
        public static void RegisterGlobalFilters(GlobalFilterCollection filters)
        {
            filters.Add(new HandleErrorAttribute());
        }
    }

 WebApi異常處理過濾器：

    public class ApiExceptionAttribute : ExceptionFilterAttribute
    {
        /// <summary>
        /// 控制器方法中出現異常，會調用該方法捕獲異常
        /// </summary>
        /// <param name="filterContext">提供使用</param>
        public override void OnException(HttpActionExecutedContext filterContext)
        {
            WriteLog(filterContext);
            string jsonResult = new { code = 1, message = filterContext.Exception.Message }.ToJson();
            HttpResponseMessage result = new HttpResponseMessage { Content = new StringContent(jsonResult, System.Text.Encoding.GetEncoding("UTF-8"), "application/json") };
            filterContext.Response = result;
            base.OnException(filterContext);
        }
    }