ManagementEventWatcher.WaitForNextEvent Método

Definição

Aguarda o próximo evento que corresponde à consulta especificada chegar e, em seguida, retorna-o.Waits for the next event that matches the specified query to arrive, and then returns it.

public:
 System::Management::ManagementBaseObject ^ WaitForNextEvent();
public System.Management.ManagementBaseObject WaitForNextEvent ();
member this.WaitForNextEvent : unit -> System.Management.ManagementBaseObject
Public Function WaitForNextEvent () As ManagementBaseObject

Retornos

Um ManagementBaseObject que representa o evento recém-chegado.A ManagementBaseObject representing the newly arrived event.

Exemplos

O exemplo a seguir mostra como o cliente recebe a notificação quando uma instância do Win32_Process é criada porque a classe de evento é __InstanceCreationEvent.The following example shows how the client receives notification when an instance of Win32_Process is created because the event class is __InstanceCreationEvent. Para obter mais informações, consulte a documentação do Instrumentação de gerenciamento do Windows .For more information, see the Windows Management Instrumentation documentation. O cliente recebe eventos de forma síncrona chamando o método WaitForNextEvent.The client receives events synchronously by calling the WaitForNextEvent method. Este exemplo pode ser testado com o início de um processo, como o bloco de notas, enquanto o código de exemplo está em execução.This example can be tested by starting a process, such as Notepad, while the example code is running.

using System;
using System.Management;

// This example shows synchronous consumption of events. 
// The client is blocked while waiting for events. 

public class EventWatcherPolling 
{
    public static int Main(string[] args) 
    {
        // Create event query to be notified within 1 second of 
        // a change in a service
        WqlEventQuery query = 
            new WqlEventQuery("__InstanceCreationEvent", 
            new TimeSpan(0,0,1), 
            "TargetInstance isa \"Win32_Process\"");

        // Initialize an event watcher and subscribe to events 
        // that match this query
        ManagementEventWatcher watcher =
            new ManagementEventWatcher();
        watcher.Query = query;
        // times out watcher.WaitForNextEvent in 5 seconds
        watcher.Options.Timeout = new TimeSpan(0,0,5);
      
        // Block until the next event occurs 
        // Note: this can be done in a loop if waiting for 
        //        more than one occurrence
        Console.WriteLine(
            "Open an application (notepad.exe) to trigger an event.");
        ManagementBaseObject e = watcher.WaitForNextEvent();

        //Display information from the event
        Console.WriteLine(
            "Process {0} has been created, path is: {1}", 
            ((ManagementBaseObject)e
            ["TargetInstance"])["Name"],
            ((ManagementBaseObject)e
            ["TargetInstance"])["ExecutablePath"]);

        //Cancel the subscription
        watcher.Stop();
        return 0;
    }
}
Imports System.Management

' This example shows synchronous consumption of events. 
' The client is blocked while waiting for events. 

Public Class EventWatcherPolling
    Public Overloads Shared Function _
        Main(ByVal args() As String) As Integer

        ' Create event query to be notified within 1 second of 
        ' a change in a service
        Dim query As New WqlEventQuery( _
            "__InstanceCreationEvent", _
            New TimeSpan(0, 0, 1), _
            "TargetInstance isa ""Win32_Process""")

        ' Initialize an event watcher and subscribe to events 
        ' that match this query
        Dim watcher As New ManagementEventWatcher
        watcher.Query = query
        ' times watcher.WaitForNextEvent in 5 seconds
        watcher.Options.Timeout = New TimeSpan(0, 0, 5)

        ' Block until the next event occurs 
        ' Note: this can be done in a loop
        ' if waiting for more than one occurrence
        Console.WriteLine( _
          "Open an application (notepad.exe) to trigger an event.")
        Dim e As ManagementBaseObject = _
            watcher.WaitForNextEvent()

        'Display information from the event
        Console.WriteLine( _
            "Process {0} has created, path is: {1}", _
            CType(e("TargetInstance"), _
                ManagementBaseObject)("Name"), _
            CType(e("TargetInstance"), _
                ManagementBaseObject)("ExecutablePath"))

        'Cancel the subscription
        watcher.Stop()
        Return 0

    End Function 'Main
End Class

Comentários

Se o objeto Inspetor de eventos contiver opções com um tempo limite especificado, a API aguardará o próximo evento somente pelo período de tempo especificado; caso contrário, a API será bloqueada até que o próximo evento ocorra.If the event watcher object contains options with a specified time-out, the API will wait for the next event only for the specified amount of time; otherwise, the API will be blocked until the next event occurs.

Segurança do .NET Framework.NET Framework Security

Confiança total para o chamador imediato.Full trust for the immediate caller. Este membro não pode ser usado pelo código parcialmente confiável.This member cannot be used by partially trusted code. Para obter mais informações, consulte usando bibliotecas de código parcialmente confiável.For more information, see Using Libraries from Partially Trusted Code.

Aplica-se a