HandleErrorAttribute只能处理httpStatusCode为500的异常（服务器异常）

HandleErrorAttribute源代码：

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = true)]
    public class HandleErrorAttribute : FilterAttribute, IExceptionFilter
    {
        private const string DefaultView = "Error";
        private readonly object _typeId = new object();
        private Type _exceptionType = typeof(Exception);
        private string _master;
        private string _view;
        public Type ExceptionType
        {
            get
            {
                return this._exceptionType;
            }
            set
            {
                if (value == null)
                {
                    throw new ArgumentNullException("value");
                }
                if (!typeof(Exception).IsAssignableFrom(value))
                {
                    throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, MvcResources.ExceptionViewAttribute_NonExceptionType, new object[]
                    {
                        value.FullName
                    }));
                }
                this._exceptionType = value;
            }
        }
        public string Master
        {
            get
            {
                return this._master ?? string.Empty;
            }
            set
            {
                this._master = value;
            }
        }
        public override object TypeId
        {
            get
            {
                return this._typeId;
            }
        }
        public string View
        {
            get
            {
                if (string.IsNullOrEmpty(this._view))
                {
                    return "Error";
                }
                return this._view;
            }
            set
            {
                this._view = value;
            }
        }
        public virtual void OnException(ExceptionContext filterContext)
        {
            if (filterContext == null)
            {
                throw new ArgumentNullException("filterContext");
            }
            if (filterContext.IsChildAction)
            {
                return;
            }
            if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
            {
                return;
            }
            Exception exception = filterContext.Exception;
            if (new HttpException(null, exception).GetHttpCode() != 500)//注意这里
            {
                return;
            }
            if (!this.ExceptionType.IsInstanceOfType(exception))
            {
                return;
            }
            string controllerName = (string)filterContext.RouteData.Values["controller"];
            string actionName = (string)filterContext.RouteData.Values["action"];
            HandleErrorInfo model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);
            filterContext.Result = new ViewResult
            {
                ViewName = this.View,
                MasterName = this.Master,
                ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
                TempData = filterContext.Controller.TempData
            };
            filterContext.ExceptionHandled = true;
            filterContext.HttpContext.Response.Clear();
            filterContext.HttpContext.Response.StatusCode = 500;
            filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
        }
    }