如何解决此System.IO.FileNotFoundException错误
如何解决此System.IO.FileNotFoundException错误
- 该错误只在生产环境中发生（在调试中没有发生）。
- 该错误只在Windows登录后的第一次应用程序运行时发生。
- 当我们点击BtnUseDesktop并触发BtnUseDesktop_Click事件时，该错误发生（如下所示）。
- 事件查看器堆栈从The.Application.Name.Main()方法开始...
- 但我们的代码中没有这个方法（它是一个WPF应用程序）。
事件查看器
应用程序：The.Application.Name.exe
框架版本：v4.0.30319
描述：由于未处理的异常，进程终止。
异常信息：System.IO.FileNotFoundException
堆栈：
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(
System.Object, System.Delegate, System.Object, Int32, System.Delegate)
at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(
System.Windows.Threading.DispatcherPriority, System.TimeSpan,
System.Delegate, System.Object, Int32)
at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr, Int32, IntPtr, IntPtr)
at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)
at System.Windows.Threading.Dispatcher.PushFrameImpl(
System.Windows.Threading.DispatcherFrame)
at System.Windows.Threading.Dispatcher.PushFrame(
System.Windows.Threading.DispatcherFrame)
at System.Windows.Threading.Dispatcher.Run()
at System.Windows.Application.RunDispatcher(System.Object)
at System.Windows.Application.RunInternal(System.Windows.Window)
at System.Windows.Application.Run(System.Windows.Window)
at The.Application.Name.Main()
BtnUseDesktop_Click
private void BtnUseDesktop_Click(object sender, RoutedEventArgs e)
{
AvSwitcher switcher = new AvSwitcher();
this.RunAsyncTask(() =>
switcher.SwitchToDesktop(this.windowSyncSvc.ActiveLyncWindowHandle));
}
Click事件调用的AvSwitcher
public class AvSwitcher
{
private DeviceLocationSvc deviceLocationSvc;
private UIAutomationSvc uiAutomationSvc;
private WindowMovingSvc windowMovingSvc;
private ManualResetEvent manualResetEvent;
private Modality audioVideo;
public static bool IsSwitching { get; set; }
public AvSwitcher()
{
this.deviceLocationSvc = new DeviceLocationSvc();
this.uiAutomationSvc = new UIAutomationSvc();
this.windowMovingSvc = new WindowMovingSvc();
}
public void SwitchToDesktop(IntPtr activeLyncConvWindowHandle)
{
this.BeginHold(DeviceLocation.Desktop, activeLyncConvWindowHandle);
}
public void SwitchToWall(IntPtr activeLyncConvWindowHandle)
{
this.BeginHold(DeviceLocation.Wall, activeLyncConvWindowHandle);
}
private Conversation GetLyncConversation()
{
Conversation conv = null;
if (LyncClient.GetClient() != null)
{
conv = LyncClient.GetClient().ConversationManager.Conversations.FirstOrDefault();
}
return conv;
}
private void BeginHold(DeviceLocation targetLocation, IntPtr activeLyncConvWindowHandle)
{
AvSwitcher.IsSwitching = true;
// make sure the class doesn't dispose of itself
this.manualResetEvent = new ManualResetEvent(false);
Conversation conv = this.GetLyncConversation();
if (conv != null)
{
this.audioVideo = conv.Modalities[ModalityTypes.AudioVideo];
ModalityState modalityState = this.audioVideo.State;
if (modalityState == ModalityState.Connected)
{
this.HoldCallAndThenDoTheSwitching(targetLocation, activeLyncConvWindowHandle);
}
else
{
this.DoTheSwitching(targetLocation, activeLyncConvWindowHandle);
}
}
}
private void HoldCallAndThenDoTheSwitching(
DeviceLocation targetLocation,
IntPtr activeLyncConvWindowHandle)
{
try
{
this.audioVideo.BeginHold(
this.BeginHold_callback,
new AsyncStateValues()
{
TargetLocation = targetLocation,
ActiveLyncConvWindowHandle = activeLyncConvWindowHandle
});
this.manualResetEvent.WaitOne();
}
catch (UnauthorizedAccessException)
{
// the call is already on hold
this.DoTheSwitching(targetLocation, activeLyncConvWindowHandle);
}
}
private void BeginHold_callback(IAsyncResult ar)
{
if (ar.IsCompleted)
{
DeviceLocation targetLocation = ((AsyncStateValues)ar.AsyncState).TargetLocation;
IntPtr activeLyncConvWindowHandle =
((AsyncStateValues)ar.AsyncState).ActiveLyncConvWindowHandle;
this.DoTheSwitching(targetLocation, activeLyncConvWindowHandle);
}
Thread.Sleep(2000); // is this necessary
this.audioVideo.BeginRetrieve(this.BeginRetrieve_callback, null);
}
private void DoTheSwitching(DeviceLocation targetLocation, IntPtr activeLyncConvWindowHandle)
{
DeviceLocationSvc.TargetDevices targetDevices =
this.deviceLocationSvc.GetTargetDevices(targetLocation);
this.SwitchScreenUsingWinApi(targetDevices.Screen, activeLyncConvWindowHandle);
this.SwitchVideoUsingLyncApi(targetDevices.VideoDevice);
this.SwitchAudioUsingUIAutomation(
targetDevices.MicName,
targetDevices.SpeakersName,
activeLyncConvWindowHandle);
AvSwitcher.IsSwitching = false;
}
private void SwitchScreenUsingWinApi(Screen targetScreen, IntPtr activeLyncConvWindowHandle)
{
if (activeLyncConvWindowHandle != IntPtr.Zero)
{
WindowPosition wp =
this.windowMovingSvc.GetTargetWindowPositionFromScreen(targetScreen);
this.windowMovingSvc.MoveTheWindowToTargetPosition(activeLyncConvWindowHandle, wp);
}
}
private void SwitchVideoUsingLyncApi(VideoDevice targetVideoDevice)
{
if (targetVideoDevice != null)
{
LyncClient.GetClient().DeviceManager.ActiveVideoDevice = targetVideoDevice;
}
}
private void SwitchAudioUsingUIAutomation(
string targetMicName,
string targetSpeakersName,
IntPtr activeLyncConvWindowHandle)
{
if (targetMicName != null && targetSpeakersName != null)
{
AutomationElement lyncConvWindow =
AutomationElement.FromHandle(activeLyncConvWindowHandle);
AutomationElement lyncOptionsWindow =
this.uiAutomationSvc.OpenTheLyncOptionsWindowFromTheConvWindow(lyncConvWindow);
this.uiAutomationSvc.SelectTheTargetMic(lyncOptionsWindow, targetMicName);
this.uiAutomationSvc.SelectTheTargetSpeakers(lyncOptionsWindow, targetSpeakersName);
this.uiAutomationSvc.InvokeOkayButton(lyncOptionsWindow);
}
}
private void BeginRetrieve_callback(IAsyncResult ar)
{
this.audioVideo.EndRetrieve(ar);
this.manualResetEvent.Set(); // allow the program to exit
}
private class AsyncStateValues
{
internal DeviceLocation TargetLocation { get; set; }
internal IntPtr ActiveLyncConvWindowHandle { get; set; }
}
}
在解决System.IO.FileNotFoundException的问题上，我曾经被误导过不止一次。花费了几个小时进行谷歌搜索、更新nuget包、版本检查，然后坐在一个完全更新的解决方案旁边，我重新意识到了产生这个错误的一个完全有效、更简单的原因。
如果在一个多线程的环境中（例如UI Dispatcher.Invoke），当线程管理器dll（文件）无法返回时，就会抛出System.IO.FileNotFoundException。所以，如果你的主UI线程A调用系统线程管理器dll B，而B调用你的线程代码C，但C由于一些不相关的原因（例如我遇到的空引用）而抛出异常，那么C就无法返回，B也无法返回，而A只会因为B丢失而责怪B抛出了FileNotFoundException。
在走上dll版本的路径之前...更仔细地检查一下你的线程代码是否抛出异常。
如何解决System.IO.FileNotFoundException问题
System.IO.FileNotFoundException意味着程序找不到指定的文件。因此，您需要检查代码在生产环境中要查找的文件。为了查看程序在生产环境中要查找的文件（查看异常的FileName属性），可以尝试以下技术：
1.写入调试日志（debug log）；
2.使用Visual Studio Attach to Process；
3.使用Visual Studio Remote Debugging。
然后，查看计算机上的文件系统，看看文件是否存在。很可能的情况是文件不存在。
我将这个答案标记为正确答案，因为它引导我使用了"attach to process"。然后我编辑了答案，将"attach to process"作为生产调试选项。
“写入调试日志”是什么意思以及要写什么？
这意味着您需要存储一些记录，记录发生了什么以及调试时有用的相关信息。您可以自己开发日志记录解决方案，但强烈建议查看现有的日志库，如Serilog、NLog等。
这是否意味着无法从事件查看器提供的数据中找出缺失的文件？
这取决于事件查看器中的内容。我肯定不会依赖它的内容。将日志记录掌握在自己手中，这样您可以完全控制记录了哪些信息。
