Question

在阅读了一些关于AppDomain.UnhandledException和Application.DispatcherUnhandledException之间差异的优秀帖子之后，看来我应该同时处理它们。这是因为用户可以从主UI线程抛出的异常（即Application.DispatcherUnhandledException）中恢复的可能性更大。正确的吗？

另外，我是否应该让用户有机会继续这两个程序，或者仅仅是Application.DispatcherUnhandledException？

下面的示例代码处理AppDomain.UnhandledException和Application.DispatcherUnhandledException，并且两者都为用户提供了尝试继续的选项，尽管有异常。

[谢谢，下面的一些代码从其他答案中解脱出来]

的App.xaml

<Application x:Class="MyProgram.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Startup="App_StartupUriEventHandler"
         Exit="App_ExitEventHandler"
         DispatcherUnhandledException="AppUI_DispatcherUnhandledException">
    <Application.Resources>
    </Application.Resources>
</Application>

App.xaml.cs [编辑]

/// <summary>
/// Add dispatcher for Appdomain.UnhandledException
/// </summary>
public App()
    : base()
{
    this.Dispatcher.UnhandledException += OnDispatcherUnhandledException;
}

/// <summary>
/// Catch unhandled exceptions thrown on the main UI thread and allow 
/// option for user to continue program. 
/// The OnDispatcherUnhandledException method below for AppDomain.UnhandledException will handle all other exceptions thrown by any thread.
/// </summary>
void AppUI_DispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e)
{
    if (e.Exception == null)
    {
        Application.Current.Shutdown();
        return;
    }
    string errorMessage = string.Format("An application error occurred. If this error occurs again there seems to be a serious bug in the application, and you better close it.\n\nError:{0}\n\nDo you want to continue?\n(if you click Yes you will continue with your work, if you click No the application will close)", e.Exception.Message);
    //insert code to log exception here
    if (MessageBox.Show(errorMessage, "Application User Interface Error", MessageBoxButton.YesNoCancel, MessageBoxImage.Error) == MessageBoxResult.No)
    {
        if (MessageBox.Show("WARNING: The application will close. Any changes will not be saved!\nDo you really want to close it?", "Close the application!", MessageBoxButton.YesNoCancel, MessageBoxImage.Warning) == MessageBoxResult.Yes)
        {
            Application.Current.Shutdown();
        }
    }
    e.Handled = true;
}

/// <summary>
/// Catch unhandled exceptions not thrown by the main UI thread.
/// The above AppUI_DispatcherUnhandledException method for DispatcherUnhandledException will only handle exceptions thrown by the main UI thread. 
/// Unhandled exceptions caught by this method typically terminate the runtime.
/// </summary>
void OnDispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e)
{
    string errorMessage = string.Format("An application error occurred. If this error occurs again there seems to be a serious bug in the application, and you better close it.\n\nError:{0}\n\nDo you want to continue?\n(if you click Yes you will continue with your work, if you click No the application will close)", e.Exception.Message);
    //insert code to log exception here
    if (MessageBox.Show(errorMessage, "Application UnhandledException Error", MessageBoxButton.YesNoCancel, MessageBoxImage.Error) == MessageBoxResult.No)
    {
        if (MessageBox.Show("WARNING: The application will close. Any changes will not be saved!\nDo you really want to close it?", "Close the application!", MessageBoxButton.YesNoCancel, MessageBoxImage.Warning) == MessageBoxResult.Yes)
        {
            Application.Current.Shutdown();
        }
    }
    e.Handled = true;
}

Answer 1

AppDomain.CurrentDomain.UnhandledException捕获appdomain所有线程上的所有异常。但我发现这非常不可靠。
Application.Current.DispatcherUnhandledException捕获UI线程上的所有异常。这似乎可靠地工作，并将替换UI线程上的AppDomain.CurrentDomain.UnhandledException处理程序（优先级）。使用e.Handled = true保持应用程序正常运行。
为了捕获其他线程上的异常（在最好的情况下，它们是在自己的线程上处理的），我发现System.Threading.Tasks.Task（仅限.NET 4.0及更高版本）是低维护的。使用方法.ContinueWith(...,TaskContinuationOptions.OnlyOnFaulted)处理任务中的异常。有关详细信息，请参阅我的回答here。

Answer 2

AppDomain.UnhandledException处理程序连接为：

AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;

但是我找不到一种方法来标记处理程序中的处理 - 所以这似乎总会导致应用程序关闭，无论你做什么。所以我认为这不是很多用途。

最好处理Application.Current.DispatcherUnhandledException并测试CommunicationObjectFaultedException - 因为只需重新初始化代理就可以从中恢复 - 就像在初始连接时一样。例如：

void Current_DispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e) {
    if (e.Exception is CommunicationObjectFaultedException) { //|| e.Exception is InvalidOperationException) {
        Reconnect();
        e.Handled = true;
    }
    else {
        MessageBox.Show(string.Format("An unexpected error has occured:\n{0}.\nThe application will close.", e.Exception));
        Application.Current.Shutdown();
    }
}

public bool Reconnect() {
    bool ok = false;
    MessageBoxResult result = MessageBox.Show("The connection to the server has been lost.  Try to reconnect?", "Connection lost", MessageBoxButton.YesNo);
    if (result == MessageBoxResult.Yes)
        ok = Initialize();
    if (!ok)
        Application.Current.Shutdown();
}

其中Initialize具有您的初始代理实例化/连接代码。

在您上面发布的代码中，我怀疑您正在处理DispatcherUnhandledException 两次 - 通过在xaml和代码中连接处理程序。

应该同时使用AppDomain.UnhandledException和Application.DispatcherUnhandledException吗？

2 个答案: