AggregateException.Handle(Func<Exception,Boolean>) Método
Definición
Importante
Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.
Invoca un controlador en cada Exception contenida por esta AggregateException.
public:
void Handle(Func<Exception ^, bool> ^ predicate);public void Handle (Func<Exception,bool> predicate);member this.Handle : Func<Exception, bool> -> unitPublic Sub Handle (predicate As Func(Of Exception, Boolean))Parámetros
Predicado que se va a ejecutar para cada excepción. El predicado acepta como argumento la Exception que va a procesarse y devuelve un valor booleano para indicar si se controló la excepción.
Excepciones
El argumento predicate es null.
No se controló una excepción contenida por esta AggregateException.
Ejemplos
Normalmente, un controlador de excepciones que detecta una AggregateException excepción usa un foreach bucle (en C#) o For Each bucle (en Visual Basic) para controlar cada excepción de su InnerExceptions colección. En su lugar, en el ejemplo siguiente se usa el Handle método para controlar cada excepción y solo se reinician las excepciones que no CustomException son instancias.
using System;
using System.Threading.Tasks;
public class Example
{
public static void Main()
{
var task1 = Task.Run( () => { throw new CustomException("This exception is expected!"); } );
try {
task1.Wait();
}
catch (AggregateException ae)
{
// Call the Handle method to handle the custom exception,
// otherwise rethrow the exception.
ae.Handle(ex => { if (ex is CustomException)
Console.WriteLine(ex.Message);
return ex is CustomException;
});
}
}
}
public class CustomException : Exception
{
public CustomException(String message) : base(message)
{}
}
// The example displays the following output:
// This exception is expected!
open System
open System.Threading.Tasks
type CustomException(message) =
inherit Exception(message)
let task1 =
Task.Run(fun () -> raise (CustomException "This exception is expected!"))
try
task1.Wait()
with
| :? AggregateException as ae ->
// Call the Handle method to handle the custom exception,
// otherwise rethrow the exception.
ae.Handle (fun ex ->
if ex :? CustomException then
printfn $"{ex.Message}"
ex :? CustomException)
// The example displays the following output:
// This exception is expected!
Imports System.Threading.Tasks
Module Example
Public Sub Main()
Dim task1 = Task.Run(Sub() Throw New CustomException("This exception is expected!"))
Try
task1.Wait()
Catch ae As AggregateException
' Call the Handle method to handle the custom exception,
' otherwise rethrow the exception.
ae.Handle(Function(e)
If TypeOf e Is CustomException Then
Console.WriteLine(e.Message)
End If
Return TypeOf e Is CustomException
End Function)
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:
' This exception is expected!
A continuación se muestra un ejemplo más completo que usa el Handle método para proporcionar un control especial para un UnauthorizedAccessException objeto al enumerar archivos.
using System;
using System.IO;
using System.Threading.Tasks;
public class Example2
{
public static void Main()
{
// This should throw an UnauthorizedAccessException.
try {
var files = GetAllFiles(@"C:\");
if (files != null)
foreach (var file in files)
Console.WriteLine(file);
}
catch (AggregateException ae) {
foreach (var ex in ae.InnerExceptions)
Console.WriteLine("{0}: {1}", ex.GetType().Name, ex.Message);
}
Console.WriteLine();
// This should throw an ArgumentException.
try {
foreach (var s in GetAllFiles(""))
Console.WriteLine(s);
}
catch (AggregateException ae) {
foreach (var ex in ae.InnerExceptions)
Console.WriteLine("{0}: {1}", ex.GetType().Name, ex.Message);
}
}
static string[] GetAllFiles(string path)
{
var task1 = Task.Run( () => Directory.GetFiles(path, "*.txt",
SearchOption.AllDirectories));
try {
return task1.Result;
}
catch (AggregateException ae) {
ae.Handle( x => { // Handle an UnauthorizedAccessException
if (x is UnauthorizedAccessException) {
Console.WriteLine("You do not have permission to access all folders in this path.");
Console.WriteLine("See your network administrator or try another path.");
}
return x is UnauthorizedAccessException;
});
return Array.Empty<String>();
}
}
}
// The example displays the following output:
// You do not have permission to access all folders in this path.
// See your network administrator or try another path.
//
// ArgumentException: The path is not of a legal form.
open System
open System.IO
open System.Threading.Tasks
let getAllFiles path =
let task1 =
Task.Run(fun () -> Directory.GetFiles(path, "*.txt", SearchOption.AllDirectories))
try
task1.Result
with
| :? AggregateException as ae ->
ae.Handle (fun x ->
// Handle an UnauthorizedAccessException
if x :? UnauthorizedAccessException then
printfn "You do not have permission to access all folders in this path."
printfn "See your network administrator or try another path."
x :? UnauthorizedAccessException)
Array.empty
// This should throw an UnauthorizedAccessException.
try
let files = getAllFiles @"C:\"
if not (isNull files) then
for file in files do
printfn $"{file}"
with
| :? AggregateException as ae ->
for ex in ae.InnerExceptions do
printfn $"{ex.GetType().Name}: {ex.Message}"
printfn ""
// This should throw an ArgumentException.
try
for s in getAllFiles "" do
printfn $"{s}"
with
| :? AggregateException as ae ->
for ex in ae.InnerExceptions do
printfn $"{ex.GetType().Name}: {ex.Message}"
// The example displays the following output:
// You do not have permission to access all folders in this path.
// See your network administrator or try another path.
//
// ArgumentException: The path is empty. (Parameter 'path')
Imports System.IO
Imports System.Threading.Tasks
Module Example
Public Sub Main()
' This should throw an UnauthorizedAccessException.
Try
Dim files = GetAllFiles("C:\")
If files IsNot Nothing Then
For Each file In files
Console.WriteLine(file)
Next
End If
Catch ae As AggregateException
For Each ex In ae.InnerExceptions
Console.WriteLine("{0}: {1}", ex.GetType().Name, ex.Message)
Next
End Try
Console.WriteLine()
' This should throw an ArgumentException.
Try
For Each s In GetAllFiles("")
Console.WriteLine(s)
Next
Catch ae As AggregateException
For Each ex In ae.InnerExceptions
Console.WriteLine("{0}: {1}", ex.GetType().Name, ex.Message)
Next
End Try
Console.WriteLine()
End Sub
Function GetAllFiles(ByVal path As String) As String()
Dim task1 = Task.Run( Function()
Return Directory.GetFiles(path, "*.txt",
SearchOption.AllDirectories)
End Function)
Try
Return task1.Result
Catch ae As AggregateException
ae.Handle( Function(x)
' Handle an UnauthorizedAccessException
If TypeOf x Is UnauthorizedAccessException Then
Console.WriteLine("You do not have permission to access all folders in this path.")
Console.WriteLine("See your network administrator or try another path.")
End If
Return TypeOf x Is UnauthorizedAccessException
End Function)
End Try
Return Array.Empty(Of String)()
End Function
End Module
' The example displays the following output:
' You do not have permission to access all folders in this path.
' See your network administrator or try another path.
'
' ArgumentException: The path is not of a legal form.
Comentarios
Cada invocación de predicate devuelve true o false para indicar si se controló .Exception Después de todas las invocaciones, si alguna excepción no se ha controlado, todas las excepciones no controladas se colocarán en un nuevo AggregateException elemento que se producirá. De lo contrario, el Handle método simplemente devuelve. Si alguna invocación de predicate inicia una excepción, detendrá el procesamiento de más excepciones y propagará inmediatamente la excepción iniciada tal y como está.
