WqlEventQuery.WithinInterval 屬性

定義

命名空間:

System.Management

組件:

System.Management.dll

套件:

System.Management v8.0.0

來源:

ManagementQuery.cs

取得或設定要用於這個查詢中的輪詢間隔。

public:
 property TimeSpan WithinInterval { TimeSpan get(); void set(TimeSpan value); };

public TimeSpan WithinInterval { get; set; }

member this.WithinInterval : TimeSpan with get, set

Public Property WithinInterval As TimeSpan

屬性值

TimeSpan

傳回 TimeSpan 值，內含事件查詢中所用的輪詢間隔。

範例

下列範例會初始化新的 WqlEventQuery ，代表查詢：「SELECT * FROM __InstanceCreationEvent WITHIN 1 WHERE TargetInstance ISA 'Win32_Process'“。

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 new process being created
        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(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 seconds of 
        ' a process being created
        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(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

備註

只有在要求 的事件沒有事件提供者 的情況下，才應該設定這個屬性，而且需要 WMI 才能輪詢要求的條件。

設定這個屬性值會覆寫儲存在 物件中的任何先前值。 系統會重建查詢字串以反映新的間隔。

屬性值

Null，如果沒有涉及輪詢，則為 Null;否則，如果需要輪詢，則為有效的 TimeSpan 值。

.NET Framework 安全性

完全信任立即呼叫者。 這個成員無法供部分信任的程式碼使用。 如需詳細資訊，請參閱 使用部分信任程式代碼的連結庫。