C# Xamarin - 关闭 ProgressDialog 时应用程序崩溃

Question

我正在开发 android Xamarin 应用程序。我的应用程序连接到我的网站，因为它持续时间很长，所以我使用 ProgressDialog。但是当 ProgressDialog 关闭时，应用程序崩溃。我不明白为什么。我试图捕获错误，但应用程序也崩溃了。 （对不起我的英语）

代码如下：

ProgressDialog load;
void FTPConnection()
        {
            load = new ProgressDialog(this);
            load.SetTitle("Načítání");
            load.SetMessage("Spojování s ftp://kolemzeme.wz.cz, může to chvíli trvat...");
            load.SetCancelable(false);
            load.SetProgressStyle(ProgressDialogStyle.Spinner);
            load.Show();

            new Thread(new ThreadStart(async delegate
            {
                await Task.Delay(1000);
                try
                {
                    using (WebClient client = new WebClient())
                    {
                        Stream stream = client.OpenRead("http://" + web);
                        stream.Close();
                    }
                    FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://" + web + "/cesta.txt");
                    request.Credentials = new NetworkCredential(web, pass);
                    request.UseBinary = true;
                    request.UsePassive = true;
                    request.Method = WebRequestMethods.Ftp.GetFileSize;
                    try
                    {
                        FtpWebResponse respose = (FtpWebResponse)request.GetResponse();
                        RunOnUiThread(() =>
                        {
                            load.Dismiss();
                        });
                        NaCeste();
                    }
                    catch (WebException ex)
                    {
                        RunOnUiThread(() =>
                        {
                            load.Dismiss();
                        });
                        FtpWebResponse response = (FtpWebResponse)ex.Response;
                        SetContentView(Resource.Layout.Cesta);
                        Cesta();
                    }
                }
                catch (Exception ex)
                {
                    RunOnUiThread(() => 
                    {
                        load.Dismiss();
                    });
                    load.Dismiss();
                    AlertDialog.Builder builder = new AlertDialog.Builder(this);
                    builder.SetTitle("Nelze se připojit na FTP!")
                           .SetMessage("Aplikace nemůže navázat přístup k serveru FTP: http://kolemzeme.wz.cz\n\nPravděpodobně nemáte internet, nebo je server nyní nedostupný. Zkuste to později.\n\nError: " + ex.Message)
                           .SetCancelable(false)
                           .SetPositiveButton("Připojit se k wifi", delegate
                           {
                               Intent i = new Intent(Android.Provider.Settings.ActionWifiSettings);
                               StartActivityForResult(i, 0);
                               FTPConnection();

                           })
                           .SetNeutralButton("Opakovat", delegate
                           {
                               FTPConnection();
                           })
                           .SetNegativeButton("Odejít", delegate
                           {
                               Finish();
                           })
                           .Show();
                }
            })).Start();
        }

错误的屏幕截图 here。

Answer 1

RunOnUiThread(() => 
{
    load.Dismiss();
});
load.Dismiss();

您在 UI 线程上有一个 Dismiss 调用运行，一个没有。您需要删除第二个。

更好的方法是将异常处理的所有移动到 UI 线程。所以改变：

RunOnUiThread(() =>
{
    load.Dismiss();
});
FtpWebResponse response = (FtpWebResponse)ex.Response;
SetContentView(Resource.Layout.Cesta);
Cesta();

至：

RunOnUiThread(() =>
{
    load.Dismiss();
    FtpWebResponse response = (FtpWebResponse)ex.Response;
    SetContentView(Resource.Layout.Cesta);
    Cesta();
});

（例如 - 您需要对所有 catch 块进行这种样式的更改）

C# Xamarin - 关闭 ProgressDialog 时应用程序崩溃

C# Xamarin - Application crashes, when dismiss ProgressDialog

c#

android

progressdialog

xamarin