通过尝试实现WP8应用程序的背景代理，大麻烦

Question

我有一个公共库'datalib'：

namespace DataLib
{
public class DataLib
{
    public async static Task<List<String>> Daten()
    {
        //here is a http request witch call data from the internet in write it to file within isoStorage
        //than the content of this files will be written into var1, var2, var3... to return them at the end
        //than I creat an instans of an UserControl witch generate Images to the IsoStore using data from the IsoStore genarated at the beginning...
        var TestTile = new Tiles();
        //...and the tile will be updated here with the image form the isoStorage
        return new List<String> { var1, var2 var3 ... };
    }
}

UserControll"瓷砖"看起来像这样：

namespace DataLib
{
    public partial class Tiles : UserControl
    {
        public Tiles()
        {
            InitializeComponent();
            //some stuff to generate the image and write it into isoStorage
        }    
    }
}

在应用程序中，我正在使用var1，var2，var3 ...像这样：

private async void Hauptfunktion()
{
    List<String> DatenPacket = await DataLib.DataLib.Daten();
    string var1 = DatenPacket[0].ToString();
    string var2 = DatenPacket[0].ToString();
    string var3 = DatenPacket[0].ToString();
    ...
}

所有这些都可以正常工作，但是现在我必须在背景代理中运行此漏洞这个代理" cwtaskagent"看起来像这样：

protected override async void OnInvoke(ScheduledTask task)
    { 
        await DataLib.DataLib.Daten();
        if (Debugger.IsAttached)
        {
            ScheduledActionService.LaunchForTest(task.Name, TimeSpan.FromSeconds(30));
        }
        NotifyComplete();
    }

遵循教程后，我在app.xaml.cs ...中具有此代码...

private void Application_Launching(object sender, LaunchingEventArgs e)
    {
        string taskName = "CWTaskAgent";
        PeriodicTask oldTask = ScheduledActionService.Find(taskName) as PeriodicTask;
        if (oldTask != null)
        {
            ScheduledActionService.Remove(taskName);
        }
        PeriodicTask task = new PeriodicTask(taskName);
        task.Description = "Change Livetile";
        ScheduledActionService.Add(task);
        if (Debugger.IsAttached)
        {
            ScheduledActionService.LaunchForTest(task.Name, TimeSpan.FromSeconds(10));
        }
    }

...以及wmappmanifest.xml中的此代码：

<ExtendedTask Name="CWTaskAgent">
    <BackgroundServiceAgent Specifier="ScheduledTaskAgent" Name="CWTaskAgent" Source="CWTaskAgent" Type="CWTaskAgent.ScheduledAgent"/>  
  </ExtendedTask>

so，现在如果我在模拟器中运行它，我会在10秒钟左右后会出现两个错误，当代理人启动...

时

1. 'system..io.filenotfoundexception'类型的例外（第一次机会）发生在mscorlib.ni.dll中。

2. 'system.unauthorizedAccessexceptio'类型的例外（第一次机会）发生在mscorlib.ni.dll中。

标记的线是'var testtile = new tiles（）;'在datalib.cs

中

更新：用于阅读和编写文件的代码：

using (Mutex mutex1 = new Mutex())
            {
                mutex1.WaitOne();
                try
                {
                    IsolatedStorageFileStream WritingStream = new IsolatedStorageFileStream("TagMonatJahr.txt", FileMode.Create, DatenDateien);
                    StreamWriter writer = new StreamWriter(WritingStream);
                    writer.Write(DateTime.Now.ToString("ddMMyyyy"));
                    writer.Close();
}
finally
    {
        mutex1.ReleaseMutex();
    }
}

using (Mutex mutex2 = new Mutex())
{
mutex2.WaitOne();
try
{
    IsolatedStorageFileStream ReadingStream = new IsolatedStorageFileStream("TagMonatJahr.txt", FileMode.Open, DatenDateien);
    StreamReader reader = new StreamReader(ReadingStream);
    TagMonatJahr = reader.ReadToEnd();
    reader.Close();
}
    finally
    {
        mutex2.ReleaseMutex();
    }
}

Answer 1

检查此线程。看起来您正在尝试使用UI代码而无需进行调度器。因此，尝试此代码：

protected override void OnInvoke(ScheduledTask task)
{ 
 Deployment.Current.Dispatcher.BeginInvoke( async () =>
 {
      await DataLib.DataLib.Daten();
      NotifyComplete();
 });
}