javascript - 如何处理 asp.net Httphandler 中的错误？

Question

我在 asp.net 中有返回文件的 Httphandler。在代码中我有 Response.AddHeader("Content-Disposition", "attachment; filename=somefile.ext");所以页面 URL 保持不变。但如果 Httphandler URL 出现错误，就会变成这样 http://localhost:55161/document.axd我有白屏。

如何在不刷新页面的情况下从 Httphandler 返回 javascript 警报？像这样的事情:

public class Document: IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        HttpRequest Request = context.Request;
        HttpResponse Response = context.Response;

        //Response.AddHeader("Content-Disposition", "attachment; filename=somefile.ext");
        Response.ContentType = "application/javascript";
        Response.Write("<script type ='text/javascript'>alert('Error!');</script>");

    }

    public bool IsReusable
    {
        get { return false; }
    }
}

PS，对不起我的英语，我不是母语:)

Answer 1

我认为你这样做是错误的。您不应该从 http 处理程序返回 javascript。它们旨在用于处理数据。应根据 Httphandler 执行的结果显示警报。

您可以做的是将 try catch block 放入您的 http 处理程序中，并在出现异常时返回特定代码作为结果。然后在您的 javascript 中 - 检查该代码 - 并显示警报。

在下面你可以找到我在这个案例中使用过的东西。它会给你一个想法 - 你有一个单独的类，其中包含执行结果 - 并返回易于通过 javascript 处理的 JSON。

        public void ProcessRequest(HttpContext context)
        {
            var result = new HandlerResult();
            var resultJson = string.Empty;
            var reqDictionary = Helper.DecryptQueryParams(context);

            try
            {
                if (!Helper.AllQueryParametersExists(reqDictionary, "userid", "topN", "time", "latitude", "logitude", "shareLocation"))
                {
                    _log.Error("Incomplete query string parameters!");

                    throw new Exception("Incomplete query string parameters!");
                }

                Guid userId;
                Guid.TryParse(reqDictionary["userid"], out userId);
                int topN;
                int.TryParse(reqDictionary["topn"], out topN);

                double minutes;
                double.TryParse(reqDictionary["time"], out minutes);

                var time = DateTime.Now.AddDays(-minutes);

                double latitude;
                double.TryParse(reqDictionary["latitude"], out latitude);
                double logitude;
                double.TryParse(reqDictionary["logitude"], out logitude);
                bool shareLocation = Helper.ParseInt(reqDictionary["sharelocation"]);

                var finalTime = new DateTime(time.Year, time.Month, time.Day, time.Hour, time.Minute, 0);

                var users = _userAccessor.Repo.FindUsers(userId, topN, finalTime, latitude,
                    logitude, shareLocation);

                var sb = new StringBuilder();

                var list = new List<UserLocation>();
                foreach (var user in users)
                {
                    var userLocation = new UserLocation
                    {
                        UserId = user.Id,
                        UserName = user.Email,
                        FullName = user.FullName,
                        Gender = user.Gender,
                        Age = user.Age,
                        Latitude = user.Latitude,
                        Longitude = user.Longitude,
                        Time = user.Time
                    };

                    list.Add(userLocation);
                }

                context.Response.Write(sb.ToString());


                result.Result = string.Empty;
                result.ResultStatus = HandlerResult.Status.Successful;
                resultJson = JsonConvert.SerializeObject(list);
                _log.Info("OK");
            }
            catch (Exception ex)
            {
                result.ResultStatus = HandlerResult.Status.Error;
                result.Result = ex.Message;
                resultJson = JsonConvert.SerializeObject(result);
                _log.Error(ex);
            }
            finally
            {
                context.Response.Clear();
                context.Response.ContentType = "text/plain";
                context.Response.Write(resultJson);
                context.Response.Flush();
                context.Response.End();

                _log.Info(resultJson);
            }
        }


   public class HandlerResult
    {
        public string Result { get; set; }

        public Guid UserId { get; set; }

        public Status ResultStatus { get; set; }

        public HandlerResult(Status resultStatus, string result)
        {
            this.ResultStatus = resultStatus;
            this.Result = result;
        }

        public HandlerResult(string result)
        {
            ResultStatus = Status.Novalue;
            this.Result = result;
        }

        public HandlerResult()
        {

        }

        public enum Status
        {
            Novalue = 0,
            Successful = 1,
            Error = 2,
            Notvaliduser = 3,
            Successfulupdate = 4,
            UserExists = 5,
            UserNotConfirmed = 6
        }
    }