Freigeben über


AggregateException.Flatten Methode

Definition

Fasst AggregateException-Instanzen zu einer einzelnen neuen Instanz zusammen.

public:
 AggregateException ^ Flatten();
public AggregateException Flatten ();
member this.Flatten : unit -> AggregateException
Public Function Flatten () As AggregateException

Gibt zurück

Eine neue zusammengefasste AggregateException.

Beispiele

Im folgenden Beispiel werden geschachtelte AggregateException -Instanzen vereinfacht und in nur einen Schleife behandelt.

using System;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      var task1 = Task.Factory.StartNew(() => {
                     var child1 = Task.Factory.StartNew(() => {
                        var child2 = Task.Factory.StartNew(() => {
                            // This exception is nested inside three AggregateExceptions.
                            throw new CustomException("Attached child2 faulted.");
                        }, TaskCreationOptions.AttachedToParent);

                        // This exception is nested inside two AggregateExceptions.
                        throw new CustomException("Attached child1 faulted.");
                     }, TaskCreationOptions.AttachedToParent);
      });

      try {
         task1.Wait();
      }
      catch (AggregateException ae) {
         foreach (var e in ae.Flatten().InnerExceptions) {
            if (e is CustomException) {
               Console.WriteLine(e.Message);
            }
            else {
               throw;
            }
         }
      }
   }
}

public class CustomException : Exception
{
   public CustomException(String message) : base(message)
   {}
}
// The example displays the following output:
//    Attached child1 faulted.
//    Attached child2 faulted.
open System
open System.Threading.Tasks

type CustomException(message) =
    inherit Exception(message)

let task1 =
    Task.Factory.StartNew (fun () ->
        let child1 =
            Task.Factory.StartNew(
                (fun () ->
                    let child2 =
                        Task.Factory.StartNew(
                            (fun () -> raise (CustomException "Attached child2 faulted,")),
                            TaskCreationOptions.AttachedToParent
                        )
                    raise (CustomException "Attached child1 faulted.")),
                TaskCreationOptions.AttachedToParent
            )
        ()
    )

try
    task1.Wait()
with
| :? AggregateException as ae ->
    for e in ae.Flatten().InnerExceptions do
        if e :? CustomException then
            printfn "%s" e.Message
        else
            reraise()
        
// The example displays the following output:
//    Attached child1 faulted.
//    Attached child2 faulted.
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim task1 = Task.Factory.StartNew(Sub()
                                           Dim child1 = Task.Factory.StartNew(Sub()
                                                                                 Dim child2 = Task.Factory.StartNew(Sub()
                                                                                                                       Throw New CustomException("Attached child2 faulted.")
                                                                                                                    End Sub,
                                                                                                                    TaskCreationOptions.AttachedToParent)
                                                                                                                    Throw New CustomException("Attached child1 faulted.")
                                                                              End Sub,
                                                                              TaskCreationOptions.AttachedToParent)
                                        End Sub)

      Try
         task1.Wait()
      Catch ae As AggregateException
         For Each ex In ae.Flatten().InnerExceptions
            If TypeOf ex Is CustomException Then
               Console.WriteLine(ex.Message)
            Else
               Throw
            End If
         Next
      End Try
   End Sub
End Module

Class CustomException : Inherits Exception
   Public Sub New(s As String)
      MyBase.New(s)
   End Sub
End Class
' The example displays the following output:
'       Attached child1 faulted.
'       Attached child2 faulted.

Sie können auch die AggregateException.Flatten-Methode verwenden, um die inneren Ausnahmen von mehreren AggregateException-Instanzen erneut auszulösen, die von mehreren Aufgaben in einer einzelnen AggregateException-Instanz ausgelöst wurden, wie im folgenden Beispiel gezeigt.

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;

public class Example2
{
   public static void Main()
   {
        try {
            ExecuteTasks();
        }
        catch (AggregateException ae) {
            foreach (var e in ae.InnerExceptions) {
                Console.WriteLine("{0}:\n   {1}", e.GetType().Name, e.Message);
            }
        }
   }

   static void ExecuteTasks()
   {
        // Assume this is a user-entered String.
        String path = @"C:\";
        List<Task> tasks = new List<Task>();

        tasks.Add(Task.Run(() => {
                             // This should throw an UnauthorizedAccessException.
                              return Directory.GetFiles(path, "*.txt",
                                                        SearchOption.AllDirectories);
                           }));

        tasks.Add(Task.Run(() => {
                              if (path == @"C:\")
                                 throw new ArgumentException("The system root is not a valid path.");
                              return new String[] { ".txt", ".dll", ".exe", ".bin", ".dat" };
                           }));

        tasks.Add(Task.Run(() => {
                               throw new NotImplementedException("This operation has not been implemented.");
                           }));

        try {
            Task.WaitAll(tasks.ToArray());
        }
        catch (AggregateException ae) {
            throw ae.Flatten();
        }
    }
}
// The example displays the following output:
//       UnauthorizedAccessException:
//          Access to the path 'C:\Documents and Settings' is denied.
//       ArgumentException:
//          The system root is not a valid path.
//       NotImplementedException:
//          This operation has not been implemented.
open System
open System.IO
open System.Threading.Tasks

let executeTasks () =
    // Assume this is a user-entered String.
    let path = @"C:\"

    let tasks =
        [| Task.Run (fun () ->
               // This should throw an UnauthorizedAccessException.
               Directory.GetFiles(path, "*.txt", SearchOption.AllDirectories))
           :> Task
           Task.Run (fun () ->
               if path = @"C:\" then
                   raise (ArgumentException "The system root is not a valid path.")

               [| ".txt"; ".dll"; ".exe"; ".bin"; ".dat" |])
           :> Task
           Task.Run(fun () -> raise (NotImplementedException "This operation has not been implemented")) |]

    try
        Task.WaitAll(tasks)
    with
    | :? AggregateException as ae -> raise (ae.Flatten())

try
    executeTasks ()
with 
| :? AggregateException as ae ->
    for e in ae.InnerExceptions do
        printfn $"{e.GetType().Name}:\n   {e.Message}"

// The example displays the following output:
//       UnauthorizedAccessException:
//          Access to the path 'C:\Documents and Settings' is denied.
//       ArgumentException:
//          The system root is not a valid path.
//       NotImplementedException:
//          This operation has not been implemented.
Imports System.Collections.Generic
Imports System.IO
Imports System.Threading.Tasks

Module Example
    Public Sub Main()
       Try
          ExecuteTasks()
       Catch ae As AggregateException
          For Each e In ae.InnerExceptions
             Console.WriteLine("{0}:{2}   {1}", e.GetType().Name, e.Message,
                               vbCrLf)
          Next
       End Try
    End Sub

    Sub ExecuteTasks()
        ' Assume this is a user-entered String.
        Dim path = "C:\"
        Dim tasks As New List(Of Task)
        
        tasks.Add(Task.Run(Function()
                             ' This should throw an UnauthorizedAccessException.
                              Return Directory.GetFiles(path, "*.txt",
                                                        SearchOption.AllDirectories)
                           End Function))

        tasks.Add(Task.Run(Function()
                              If path = "C:\" Then
                                 Throw New ArgumentException("The system root is not a valid path.")
                              End If
                              Return { ".txt", ".dll", ".exe", ".bin", ".dat" }
                           End Function))

        tasks.Add(Task.Run(Sub()
                              Throw New NotImplementedException("This operation has not been implemented.")
                           End Sub))

        Try
            Task.WaitAll(tasks.ToArray)
        Catch ae As AggregateException
            Throw ae.Flatten()
        End Try
    End Sub
End Module
' The example displays the following output:
'       UnauthorizedAccessException:
'          Access to the path 'C:\Documents and Settings' is denied.
'       ArgumentException:
'          The system root is not a valid path.
'       NotImplementedException:
'          This operation has not been implemented.

Hinweise

Wenn eine Aufgabe über einen angefügten untergeordneten Task verfügt, der eine Ausnahme auslöst, wird diese Ausnahme in eine AggregateException Ausnahme umschlossen, bevor sie an den übergeordneten Task weitergegeben wird, der diese Ausnahme in eine eigene AggregateException Ausnahme umschließt, bevor sie sie an den aufrufenden Thread weiterverbreitet. In solchen Fällen enthält die InnerExceptions Eigenschaft der Ausnahme, die AggregateException von der Task.Wait- Waitoder Task.WaitAll - Task.WaitAny Methode abgefangen wird, eine oder mehrere AggregateException Instanzen, nicht die ursprünglichen Ausnahmen, die den Fehler verursacht haben. Um zu vermeiden, geschachtelte AggregateException Ausnahmen durchlaufen zu müssen, können Sie die Flatten -Methode verwenden, um alle geschachtelten AggregateException Ausnahmen zu entfernen, sodass die InnerExceptions Eigenschaft des zurückgegebenen AggregateException Objekts die ursprünglichen Ausnahmen enthält.

Diese Methode flacht rekursiv alle Instanzen von AggregateException Ausnahmen ab, die innere Ausnahmen der aktuellen AggregateException Instanz sind. Die inneren Ausnahmen, die in der neuen AggregateException zurückgegeben werden, sind die Union aller inneren Ausnahmen aus der Ausnahmestruktur, die in der aktuellen AggregateException Instanz verwurzelt ist.

Gilt für:

Weitere Informationen