ManagementEventWatcher.WaitForNextEvent Метод

Определение

Ожидает следующего события, которое удовлетворяет заданному запросу, а затем возвращает это событие.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

Возвраты

ManagementBaseObject представляет новое возникшее событие.A ManagementBaseObject representing the newly arrived event.

Примеры

В следующем примере показано, как клиент получает уведомление при создании экземпляра Win32_Process , так как класс событий — __InstanceCreationEvent.The following example shows how the client receives notification when an instance of Win32_Process is created because the event class is __InstanceCreationEvent. Дополнительные сведения см. в документации по инструментарий управления Windows (WMI) .For more information, see the Windows Management Instrumentation documentation. Клиент получает события синхронно, вызывая метод WaitForNextEvent.The client receives events synchronously by calling the WaitForNextEvent method. Чтобы протестировать этот пример, можно во время выполнения кода запустить какой-нибудь процесс, такой как приложение Блокнот.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

Комментарии

Если объект-наблюдатель событий содержит параметры с заданным тайм-аутом, API будет ожидать следующего события только в течение указанного времени. в противном случае API будет заблокирован до наступления следующего события.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.

Безопасность платформы .NET Framework.NET Framework Security

Полное доверие для непосредственно вызывающего метода.Full trust for the immediate caller. Этот член не может быть использован частично доверенным кодом.This member cannot be used by partially trusted code. Дополнительные сведения см. в разделе Использование библиотек из частично доверенного кода.For more information, see Using Libraries from Partially Trusted Code.

Применяется к