订阅 Windows 事件日志？

Question

我正在处理一个需要经常检查某些事件的 Windows 事件日志的项目。 我想知道 - 有没有办法为某些事件创建对 Windows 事件日志的订阅？

那么，当事件发生时（例如事件 id = 00001），我可以在代码中收到通知吗？

如果这不能完成，那么我将不得不继续搜索事件日志，这效率不高。

Answer 1

当您使用 C# 时，我认为您应该使用 Windows API 来订阅某些 Windows 事件。 您可以使用 EventLogWatcher 或 EventLog 类来实现。 您可以在MSDN上找到使用 EventLog 创建 Windows 事件日志订阅的示例。

如果您更喜欢 EventLogWatcher，请参阅其有限文档。 这是我的例子：

public static void subscribe()
{
    EventLogWatcher watcher = null;
    try
    {
        EventLogQuery subscriptionQuery = new EventLogQuery(
            "Security", PathType.LogName, "*[System/EventID=4624]");

        watcher = new EventLogWatcher(subscriptionQuery);

        // Make the watcher listen to the EventRecordWritten
        // events.  When this event happens, the callback method
        // (EventLogEventRead) is called.
        watcher.EventRecordWritten +=
            new EventHandler<EventRecordWrittenEventArgs>(
                EventLogEventRead);

        // Activate the subscription
        watcher.Enabled = true;

        for (int i = 0; i < 5; i++)
        {
            // Wait for events to occur. 
            System.Threading.Thread.Sleep(10000);
        }
    }
    catch (EventLogReadingException e)
    {
        Log("Error reading the log: {0}", e.Message);
    }
    finally
    {
        // Stop listening to events
        watcher.Enabled = false;

        if (watcher != null)
        {
            watcher.Dispose();
        }
    }
    Console.ReadKey();
}

// Callback method that gets executed when an event is
// reported to the subscription.
public static void EventLogEventRead(object obj,
    EventRecordWrittenEventArgs arg)
{
    // Make sure there was no error reading the event.
    if (arg.EventRecord != null)
    {
        //////
        // This section creates a list of XPath reference strings to select
        // the properties that we want to display
        // In this example, we will extract the User, TimeCreated, EventID and EventRecordID
        //////
        // Array of strings containing XPath references
        String[] xPathRefs = new String[9];
        xPathRefs[0] = "Event/System/TimeCreated/@SystemTime";
        xPathRefs[1] = "Event/System/Computer";
        xPathRefs[2] = "Event/EventData/Data[@Name=\"TargetUserName\"]";
        xPathRefs[3] = "Event/EventData/Data[@Name=\"TargetDomainName\"]";
        // Place those strings in an IEnumberable object
        IEnumerable<String> xPathEnum = xPathRefs;
        // Create the property selection context using the XPath reference
        EventLogPropertySelector logPropertyContext = new EventLogPropertySelector(xPathEnum);

        IList<object> logEventProps = ((EventLogRecord)arg.EventRecord).GetPropertyValues(logPropertyContext);
        Log("Time: ", logEventProps[0]);
        Log("Computer: ", logEventProps[1]);
        Log("TargetUserName: ", logEventProps[2]);
        Log("TargetDomainName: ", logEventProps[3]);
        Log("---------------------------------------");

        Log("Description: ", arg.EventRecord.FormatDescription());
    }
    else
    {
        Log("The event instance was null.");
    }
}

Answer 2

这是一个简化的示例，它使用在 Windows 事件查看器的筛选器视图上的XML选项卡中生成的查询。 它加载查询返回的初始记录，然后监视任何未来的项目。

        var query = $"*[System[(EventID=1942) and TimeCreated[timediff(@SystemTime) <= 604800000]]]";
        var decoded = System.Web.HttpUtility.HtmlDecode(query);
        var eventLogQuery = new EventLogQuery("Application", PathType.LogName, decoded);
        var watcher = new EventLogWatcher(eventLogQuery, null, true);
        var count = 0;

        watcher.EventRecordWritten += (object sender, EventRecordWrittenEventArgs e) =>
        {
            count += 1;

            Console.WriteLine($"Found {count} items for query");
        };

        watcher.Enabled = true;

        for (var i = 0; i < 5; i++)
        { 
            System.Threading.Thread.Sleep(10000);
        }