ManagementEventWatcher.Query Propiedad

Definición

Espacio de nombres:

System.Management

Ensamblado:

System.Management.dll

Paquete:

System.Management v8.0.0

Source:

ManagementEventWatcher.cs

Obtiene o establece los criterios que se aplicarán a los eventos.

public:
 property System::Management::EventQuery ^ Query { System::Management::EventQuery ^ get(); void set(System::Management::EventQuery ^ value); };

public System.Management.EventQuery Query { get; set; }

member this.Query : System.Management.EventQuery with get, set

Public Property Query As EventQuery

Valor de propiedad

EventQuery

Consulta que se va a aplicar a los eventos.

Ejemplos

En el ejemplo siguiente se muestra cómo el cliente recibe una notificación cuando se crea una instancia de Win32_Process porque la clase de evento es __InstanceCreationEvent. Para obtener más información, consulte la documentación de Instrumental de administración de Windows . El cliente recibe eventos de forma sincrónica tras llamar al método WaitForNextEvent. Para probar este ejemplo, inicie un proceso, como Bloc de notas, mientras se ejecuta el código de ejemplo.

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

Comentarios

Valor de propiedad

Los criterios que se aplicarán a los eventos, que son iguales a la consulta de eventos.

Seguridad de .NET Framework

Plena confianza para el llamador inmediato. Un código de confianza parcial no puede utilizar este miembro. Para obtener más información, consulte Uso de bibliotecas de código de confianza parcial.