在没有事件源注册的情况下写入 Windows 应用程序事件日志

Question

有没有办法写入此事件日志：

或者至少是其他一些 Windows 默认日志，我不必在其中注册事件源？

Answer 1

是的，有一种方法可以写入您要查找的事件日志。 您不需要创建新的源，只需使用现有的源，它通常与 EventLog 的名称同名，并且在某些情况下，例如事件日志应用程序，无需管理权限即可访问*。

*您无法直接访问它的其他情况是安全事件日志，例如，它只能由操作系统访问。

我使用此代码直接写入事件日志应用程序：

using (EventLog eventLog = new EventLog("Application")) 
{
    eventLog.Source = "Application"; 
    eventLog.WriteEntry("Log message example", EventLogEntryType.Information, 101, 1); 
}

如您所见，EventLog 源与 EventLog 的名称相同。 原因可以在Event Sources @ Windows Dev Center中找到（我将引用源名称的部分加粗）：

Eventlog 键中的每个日志都包含称为事件源的子键。 事件源是记录事件的软件的名称。 如果应用程序很大，它通常是应用程序的名称或应用程序的子组件的名称。 您最多可以向注册表添加 16,384 个事件源。

Answer 2

您可以使用 EventLog 类，如如何：写入应用程序事件日志 (Visual C#) 中所述：

var appLog = new EventLog("Application");
appLog.Source = "MySource";
appLog.WriteEntry("Test log message");

但是，您需要使用管理权限配置此源“MySource”：

使用 WriteEvent 和 WriteEntry 将事件写入事件日志。 必须指定事件源才能写入事件； 在使用源编写第一个条目之前，您必须创建和配置事件源。

Answer 3

如 MSDN 中所述（例如https://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog(v=vs.110).aspx ），检查不存在的源并创建源需要管理员特权。

但是，可以不使用源“应用程序” 。 然而，在我在 Windows 2012 Server r2 下的测试中，我使用“应用程序”源获得了以下日志条目：

找不到来自源应用程序的事件 ID xxxx 的描述。 引发此事件的组件未安装在本地计算机上，或者安装已损坏。 您可以在本地计算机上安装或修复组件。 如果事件起源于另一台计算机，则显示信息必须与事件一起保存。 事件中包含以下信息：{我的事件条目消息}消息资源存在，但在字符串/消息表中找不到消息

我定义了以下方法来创建源：

    private string CreateEventSource(string currentAppName)
    {
        string eventSource = currentAppName;
        bool sourceExists;
        try
        {
            // searching the source throws a security exception ONLY if not exists!
            sourceExists = EventLog.SourceExists(eventSource);
            if (!sourceExists)
            {   // no exception until yet means the user as admin privilege
                EventLog.CreateEventSource(eventSource, "Application");
            }
        }
        catch (SecurityException)
        {
            eventSource = "Application";
        }

        return eventSource;
    }

我用 currentAppName = AppDomain.CurrentDomain.FriendlyName 调用它

可能可以使用 EventLogPermission 类而不是这个 try/catch，但不确定我们是否可以避免捕获。

也可以在外部创建源，例如在提升的 Powershell 中：

New-EventLog -LogName Application -Source MyApp

然后，在上述方法中使用“MyApp”将不会产生异常，并且可以使用该源创建 EventLog。

Answer 4

这是我使用的记录器类。 私有 Log() 方法中包含EventLog.WriteEntry() ，这是您实际写入事件日志的方式。 我在这里包含所有这些代码，因为它很方便。 除了记录之外，该类还将确保消息不会太长而无法写入事件日志（它将截断消息）。 如果消息太长，你会得到一个异常。 调用者还可以指定源。 如果调用者没有，这个类将获取源。 希望能帮助到你。

顺便说一句，您可以从网上获取 ObjectDumper。 我不想在这里发布所有这些。 我从这里得到了我的： C:\Program Files (x86)\Microsoft Visual Studio 10.0\Samples\1033\CSharpSamples.zip\LinqSamples\ObjectDumper

using System;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Linq;
using System.Reflection;
using Xanico.Core.Utilities;

namespace Xanico.Core
{
    /// <summary>
    /// Logging operations
    /// </summary>
    public static class Logger
    {
        // Note: The actual limit is higher than this, but different Microsoft operating systems actually have
        //       different limits. So just use 30,000 to be safe.
        private const int MaxEventLogEntryLength = 30000;

        /// <summary>
        /// Gets or sets the source/caller. When logging, this logger class will attempt to get the
        /// name of the executing/entry assembly and use that as the source when writing to a log.
        /// In some cases, this class can't get the name of the executing assembly. This only seems
        /// to happen though when the caller is in a separate domain created by its caller. So,
        /// unless you're in that situation, there is no reason to set this. However, if there is
        /// any reason that the source isn't being correctly logged, just set it here when your
        /// process starts.
        /// </summary>
        public static string Source { get; set; }

        /// <summary>
        /// Logs the message, but only if debug logging is true.
        /// </summary>
        /// <param name="message">The message.</param>
        /// <param name="debugLoggingEnabled">if set to <c>true</c> [debug logging enabled].</param>
        /// <param name="source">The name of the app/process calling the logging method. If not provided,
        /// an attempt will be made to get the name of the calling process.</param>
        public static void LogDebug(string message, bool debugLoggingEnabled, string source = "")
        {
            if (debugLoggingEnabled == false) { return; }

            Log(message, EventLogEntryType.Information, source);
        }

        /// <summary>
        /// Logs the information.
        /// </summary>
        /// <param name="message">The message.</param>
        /// <param name="source">The name of the app/process calling the logging method. If not provided,
        /// an attempt will be made to get the name of the calling process.</param>
        public static void LogInformation(string message, string source = "")
        {
            Log(message, EventLogEntryType.Information, source);
        }

        /// <summary>
        /// Logs the warning.
        /// </summary>
        /// <param name="message">The message.</param>
        /// <param name="source">The name of the app/process calling the logging method. If not provided,
        /// an attempt will be made to get the name of the calling process.</param>
        public static void LogWarning(string message, string source = "")
        {
            Log(message, EventLogEntryType.Warning, source);
        }

        /// <summary>
        /// Logs the exception.
        /// </summary>
        /// <param name="ex">The ex.</param>
        /// <param name="source">The name of the app/process calling the logging method. If not provided,
        /// an attempt will be made to get the name of the calling process.</param>
        public static void LogException(Exception ex, string source = "")
        {
            if (ex == null) { throw new ArgumentNullException("ex"); }

            if (Environment.UserInteractive)
            {
                Console.WriteLine(ex.ToString());
            }

            Log(ex.ToString(), EventLogEntryType.Error, source);
        }

        /// <summary>
        /// Recursively gets the properties and values of an object and dumps that to the log.
        /// </summary>
        /// <param name="theObject">The object to log</param>
        [SuppressMessage("Microsoft.Globalization", "CA1303:Do not pass literals as localized parameters", MessageId = "Xanico.Core.Logger.Log(System.String,System.Diagnostics.EventLogEntryType,System.String)")]
        [SuppressMessage("Microsoft.Naming", "CA1720:IdentifiersShouldNotContainTypeNames", MessageId = "object")]
        public static void LogObjectDump(object theObject, string objectName, string source = "")
        {
            const int objectDepth = 5;
            string objectDump = ObjectDumper.GetObjectDump(theObject, objectDepth);

            string prefix = string.Format(CultureInfo.CurrentCulture,
                                          "{0} object dump:{1}",
                                          objectName,
                                          Environment.NewLine);

            Log(prefix + objectDump, EventLogEntryType.Warning, source);
        }

        private static void Log(string message, EventLogEntryType entryType, string source)
        {
            // Note: I got an error that the security log was inaccessible. To get around it, I ran the app as administrator
            //       just once, then I could run it from within VS.

            if (string.IsNullOrWhiteSpace(source))
            {
                source = GetSource();
            }

            string possiblyTruncatedMessage = EnsureLogMessageLimit(message);
            EventLog.WriteEntry(source, possiblyTruncatedMessage, entryType);

            // If we're running a console app, also write the message to the console window.
            if (Environment.UserInteractive)
            {
                Console.WriteLine(message);
            }
        }

        private static string GetSource()
        {
            // If the caller has explicitly set a source value, just use it.
            if (!string.IsNullOrWhiteSpace(Source)) { return Source; }

            try
            {
                var assembly = Assembly.GetEntryAssembly();

                // GetEntryAssembly() can return null when called in the context of a unit test project.
                // That can also happen when called from an app hosted in IIS, or even a windows service.

                if (assembly == null)
                {
                    assembly = Assembly.GetExecutingAssembly();
                }


                if (assembly == null)
                {
                    // From http://stackoverflow.com/a/14165787/279516:
                    assembly = new StackTrace().GetFrames().Last().GetMethod().Module.Assembly;
                }

                if (assembly == null) { return "Unknown"; }

                return assembly.GetName().Name;
            }
            catch
            {
                return "Unknown";
            }
        }

        // Ensures that the log message entry text length does not exceed the event log viewer maximum length of 32766 characters.
        private static string EnsureLogMessageLimit(string logMessage)
        {
            if (logMessage.Length > MaxEventLogEntryLength)
            {
                string truncateWarningText = string.Format(CultureInfo.CurrentCulture, "... | Log Message Truncated [ Limit: {0} ]", MaxEventLogEntryLength);

                // Set the message to the max minus enough room to add the truncate warning.
                logMessage = logMessage.Substring(0, MaxEventLogEntryLength - truncateWarningText.Length);

                logMessage = string.Format(CultureInfo.CurrentCulture, "{0}{1}", logMessage, truncateWarningText);
            }

            return logMessage;
        }
    }
}

Answer 5

尝试

   System.Diagnostics.EventLog appLog = new System.Diagnostics.EventLog();
   appLog.Source = "This Application's Name";
   appLog.WriteEntry("An entry to the Application event log.");