使用条件布局用不同的布局记录每个日志级别的更简单方法

<variable name="VerboseLayout" value="${level:uppercase=true}: ${longdate} | ${logger}    : 
${when:when=level == LogLevel.Trace:inner=MONITOR_TRACE ${message}} 
${when:when=level == LogLevel.Debug:inner=MONITOR_DEBUG ${message}} 
${when:when=level == LogLevel.Info:inner=MONITOR_INFO ${message}} 
${when:when=level == LogLevel.Warn:inner=MONITOR_WARN ${message}} 
${when:when=level == LogLevel.Error:inner=MONITOR_ERROR ${message}} 
${when:when=level == LogLevel.Fatal:inner=MONITOR_CRITICAL ${message}} |     
${exception:format=tostring} | ${newline} ${newline}" />

参见https://github.com/NLog/NLog/wiki/When-Filter查看语法

来自Silverlight的日志

当使用NLog和Silverlight一起使用时，你可以通过提供的web服务将跟踪发送到服务器端。你也可以写入隔离存储中的本地文件，如果web服务器不可用，这就派上用场了。请看这里的细节，也就是说，用一些类似的东西来让自己成为一个目标:

namespace NLogTargets
{
    [Target("IsolatedStorageTarget")]
    public sealed class IsolatedStorageTarget : TargetWithLayout
    {
        IsolatedStorageFile _storageFile = null;
        string _fileName = "Nlog.log"; // Default. Configurable through the 'filename' attribute in nlog.config

        public IsolatedStorageTarget()
        {
        }

        ~IsolatedStorageTarget()
        {
            if (_storageFile != null)
            {
                _storageFile.Dispose();
                _storageFile = null;
            }
        }

        public string filename
        {
            set
            {
                _fileName = value; 
            }
            get
            {
                return _fileName;  
            }
         }

        protected override void Write(LogEventInfo logEvent)
        {
            try
            {
                writeToIsolatedStorage(this.Layout.Render(logEvent));
            }
            catch (Exception e)
            {
                // Not much to do about his....
            }
        }

        public void writeToIsolatedStorage(string msg)
        {
            if (_storageFile == null)
                _storageFile = IsolatedStorageFile.GetUserStoreForApplication();
            using (IsolatedStorageFile isolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
            {
                // The isolated storage is limited in size. So, when approaching the limit
                // simply purge the log file. (Yeah yeah, the file should be circular, I know...)
                if (_storageFile.AvailableFreeSpace < msg.Length * 100)
                {
                    using (IsolatedStorageFileStream stream = new IsolatedStorageFileStream(_fileName, FileMode.Truncate, FileAccess.Write, isolatedStorage))
                    { }
                }
                // Write to isolated storage
                using (IsolatedStorageFileStream stream = new IsolatedStorageFileStream(_fileName, FileMode.Append, FileAccess.Write, isolatedStorage))
                {
                    using (TextWriter writer = new StreamWriter(stream))
                    {
                        writer.WriteLine(msg);
                    }
                }
            }
        }
    } 
}

登录Twitter

Based on this post about a log4net Twitter Appender, I thought I would try my hand at writing a NLog Twitter Target (using NLog 1.0 refresh, not 2.0). Alas, so far I have not been able to get a Tweet to actually post successfully. I don't know if it is something wrong in my code, Twitter, our company's internet connection/firewall, or what. I am posting the code here in case someone is interested in trying it out. Note that there are three different "Post" methods. The first one that I tried is PostMessageToTwitter. PostMessageToTwitter is essentially the same as PostLoggingEvent in the orignal post. If I use that I get a 401 exception. PostMessageBasic gets the same exception. PostMessage runs with no errors, but the message still does not make it up to Twitter. PostMessage and PostMessageBasic are based on examples that I found here on SO.

仅供参考——我刚刚发现了@Jason Diller对这篇文章的一个回答的评论，他说twitter将在下个月关闭基本的身份验证。这是在2010年5月，现在是2010年12月，所以我想这可能就是为什么它不起作用的原因。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Web;
using System.IO;

using NLog;
using NLog.Targets;
using NLog.Config;

namespace NLogExtensions
{
  [Target("TwitterTarget")]
  public class TwitterTarget : TargetWithLayout
  {
    private const string REQUEST_CONTENT_TYPE = "application/x-www-form-urlencoded";  

    private const string REQUEST_METHOD = "POST";  

    // The source attribute has been removed from the Twitter API,  
    // unless you're using OAuth.  
    // Even if you are using OAuth, there's still an approval process.  
    // Not worth it; "API" will work for now!  
    // private const string TWITTER_SOURCE_NAME = "Log4Net";  
    private const string TWITTER_UPDATE_URL_FORMAT = "http://twitter.com/statuses/update.xml?status={0}";  

    [RequiredParameter]
    public string TwitterUserName { get; set; }

    [RequiredParameter]
    public string TwitterPassword { get; set; }

    protected override void Write(LogEventInfo logEvent)
    {
      if (string.IsNullOrWhiteSpace(TwitterUserName) || string.IsNullOrWhiteSpace(TwitterPassword)) return;

      string msg = this.CompiledLayout.GetFormattedMessage(logEvent);

      if (string.IsNullOrWhiteSpace(msg)) return;

      try
      {
        //PostMessageToTwitter(msg);
        PostMessageBasic(msg);
      }
      catch (Exception ex)
      {
        //Should probably do something here ...
      }
    }

    private void PostMessageBasic(string msg)
    {
      // Create a webclient with the twitter account credentials, which will be used to set the HTTP header for basic authentication 
      WebClient client = new WebClient { Credentials = new NetworkCredential { UserName = TwitterUserName, Password = TwitterPassword } };

      // Don't wait to receive a 100 Continue HTTP response from the server before sending out the message body 
      ServicePointManager.Expect100Continue = false;

      // Construct the message body 
      byte[] messageBody = Encoding.ASCII.GetBytes("status=" + msg);

      // Send the HTTP headers and message body (a.k.a. Post the data) 
      client.UploadData(@"http://twitter.com/statuses/update.xml", messageBody);
    }

    private void PostMessage(string msg)
    {
      string user = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(TwitterUserName + ":" + TwitterPassword));
      byte [] bytes = System.Text.Encoding.UTF8.GetBytes("status=" + msg.ToTweet());
      HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://twitter.com/statuses/update.xml");
      request.Method = "POST";
      request.ServicePoint.Expect100Continue = false;
      request.Headers.Add("Authorization", "Basic " + user);
      request.ContentType = "application/x-www-form-urlencoded";
      request.ContentLength = bytes.Length;
      Stream reqStream = request.GetRequestStream();
      reqStream.Write(bytes, 0, bytes.Length);
      reqStream.Close();
    }

    private void PostMessageToTwitter(string msg)
    {
      var updateRequest = HttpWebRequest.Create(string.Format(TWITTER_UPDATE_URL_FORMAT,
                                                HttpUtility.UrlEncode(msg.ToTweet()))) as HttpWebRequest;
      updateRequest.ContentLength = 0;
      updateRequest.ContentType = REQUEST_CONTENT_TYPE;
      updateRequest.Credentials = new NetworkCredential(TwitterUserName, TwitterPassword);
      updateRequest.Method = REQUEST_METHOD;

      updateRequest.ServicePoint.Expect100Continue = false;

      var updateResponse = updateRequest.GetResponse() as HttpWebResponse;

      if (updateResponse.StatusCode != HttpStatusCode.OK && updateResponse.StatusCode != HttpStatusCode.Continue)
      {
        throw new Exception(string.Format("An error occurred while invoking the Twitter REST API [Response Code: {0}]", updateResponse.StatusCode));
      }
    }
  }

  public static class Extensions
  {
    public static string ToTweet(this string s)
    {
      if (string.IsNullOrEmpty(s) || s.Length < 140)
      {
        return s;
      }

      return s.Substring(0, 137) + "...";
    }
  }
}

这样配置:

告诉NLog包含目标的程序集:

<extensions>
  <add assembly="NLogExtensions"/>
</extensions>

配置目标:

<targets>
    <target name="twitter" type="TwitterTarget" TwitterUserName="yourtwittername" TwitterPassword="yourtwitterpassword" layout="${longdate} ${logger} ${level} ${message}" />
</targets>

如果有人尝试了这个方法并取得了成功，请将你的发现反馈给我们。

使用条件布局用不同的布局记录每个日志级别的更简单方法

<variable name="VerboseLayout" value="${level:uppercase=true}: ${longdate} | ${logger}    : 
${when:when=level == LogLevel.Trace:inner=MONITOR_TRACE ${message}} 
${when:when=level == LogLevel.Debug:inner=MONITOR_DEBUG ${message}} 
${when:when=level == LogLevel.Info:inner=MONITOR_INFO ${message}} 
${when:when=level == LogLevel.Warn:inner=MONITOR_WARN ${message}} 
${when:when=level == LogLevel.Error:inner=MONITOR_ERROR ${message}} 
${when:when=level == LogLevel.Fatal:inner=MONITOR_CRITICAL ${message}} |     
${exception:format=tostring} | ${newline} ${newline}" />

参见https://github.com/NLog/NLog/wiki/When-Filter查看语法

区别对待异常

当出现异常时，我们通常希望获得更多信息。下面的配置有两个目标，一个文件和控制台，它们根据是否有任何异常信息进行筛选。(编辑:Jarek已经在vNext中发布了一种新方法。)

关键是要有一个包装器目标xsi:type="FilteringWrapper" condition="length('${exception}')>0"

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.mono2.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true"
      internalLogLevel="Warn"
      internalLogFile="nlog log.log"
      >
    <variable name="VerboseLayout" 
              value="${longdate} ${level:upperCase=true} ${message}  
                    (${callsite:includSourcePath=true})"            />
    <variable name="ExceptionVerboseLayout"  
              value="${VerboseLayout} (${stacktrace:topFrames=10})  
                     ${exception:format=ToString}"                  />

    <targets async="true">
        <target name="file" xsi:type="File" fileName="log.log"
                layout="${VerboseLayout}">
        </target>

        <target name="fileAsException"  
                xsi:type="FilteringWrapper" 
                condition="length('${exception}')>0">
            <target xsi:type="File"  
                    fileName="log.log"  
                    layout="${ExceptionVerboseLayout}" />
        </target>

        <target xsi:type="ColoredConsole"
                name="console"
                layout="${NormalLayout}"/>

        <target xsi:type="FilteringWrapper"  
                condition="length('${exception}')>0"  
                name="consoleException">
            <target xsi:type="ColoredConsole" 
                    layout="${ExceptionVerboseLayout}" />
        </target>
    </targets>

    <rules>
        <logger name="*" minlevel="Trace" writeTo="console,consoleException" />
        <logger name="*" minlevel="Warn" writeTo="file,fileAsException" />
    </rules>

</nlog>

显然，你现在可以在Windows上使用NLog和Growl了。

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

    <extensions>
        <add assembly="NLog.Targets.GrowlNotify" />
    </extensions>

    <targets>
        <target name="growl" type="GrowlNotify" password="" host="" port="" />
    </targets>

    <rules>
        <logger name="*" minLevel="Trace" appendTo="growl"/>
    </rules>

</nlog>