ManagementEventWatcher.WaitForNextEvent Metoda

Definicja

Czeka na następne zdarzenie, które pasuje do określonego zapytania, a następnie zwraca go.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

Zwraca

ManagementBaseObject

ManagementBaseObjectReprezentujący nowo dostarczone zdarzenie.A ManagementBaseObject representing the newly arrived event.

Przykłady

Poniższy przykład pokazuje, jak klient otrzymuje powiadomienie po utworzeniu wystąpienia Win32_Process , ponieważ Klasa zdarzeń jest __InstanceCreationEvent.The following example shows how the client receives notification when an instance of Win32_Process is created because the event class is __InstanceCreationEvent. Aby uzyskać więcej informacji, zobacz dokumentację Instrumentacja zarządzania Windows .For more information, see the Windows Management Instrumentation documentation. Klient odbiera zdarzenia synchronicznie przez wywołanie WaitForNextEvent metody.The client receives events synchronously by calling the WaitForNextEvent method. Ten przykład może być testowany przez uruchomienie procesu, takiego jak Notatnik, podczas gdy przykładowy kod jest uruchomiony.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

Uwagi

Jeśli obiekt obserwatora zdarzeń zawiera opcje z określonym limitem czasu, interfejs API będzie oczekiwać na następne zdarzenie tylko przez określony czas; w przeciwnym razie interfejs API zostanie zablokowany do momentu wystąpienia następnego zdarzenia.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.

Zabezpieczenia.NET Framework.NET Framework Security

Pełne zaufanie do bezpośredniego wywołującego.Full trust for the immediate caller. Ten element członkowski nie może być używany przez kod częściowo zaufany.This member cannot be used by partially trusted code. Aby uzyskać więcej informacji, zobacz Używanie bibliotek z częściowo zaufanego kodu.For more information, see Using Libraries from Partially Trusted Code.

Dotyczy