一：简介
NLog是一个简单灵活的.NET日志记录类库。通过使用NLog，我们可以在任何一种.NET语言中输出带有上下文的（contextual information）调试诊断信息，根据喜好配置其表现样式之后发送到一个或多个输出目标（target）中。
详细配置文章请参考：http://www.cnblogs.com/RitchieChen/archive/2012/07/16/2594308.html
二：应用
直接在NuGet中下载Nlog包即可，需要在项目的根目录下创建NLog.config配置文件，当前文章只记录文件方式写入日志，配置文件如下：
<?xml version="1.0" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <targets>
<target name="file" xsi:type="File"
layout="${longdate} ${logger} ${message}"
fileName="${basedir}/logs/${level}.txt" //level是已文件级别作为日志名，shortdate是以时间作为日志名
keepFileOpen="false" /> </targets> <rules> <logger name="*" minlevel="Debug" writeTo="file" /> </rules> </nlog>
异步写入文件
<?xml version="1.0" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <targets>
<target name="file" xsi:type="AsyncWrapper" queueLimit="" overflowAction="Discard">
<target name="file" xsi:type="File"
layout="${longdate} ${logger} ${message}"
fileName="${basedir}/logs/${level}.txt"
keepFileOpen="false"
/>
</target>
</targets> <rules>
<logger name="*" minlevel="Debug" writeTo="file" />
</rules>
</nlog>
配置语法
<targets>
<target xsi:type="File"
name="String"
layout="Layout"
header="Layout"
footer="Layout"
encoding="Encoding"
lineEnding="Enum"
archiveAboveSize="Long"
maxArchiveFiles="Integer"
archiveFileName="Layout"
archiveNumbering="Enum"
archiveEvery="Enum"
replaceFileContentsOnEachWrite="Boolean"
fileAttributes="Enum"
fileName="Layout"
deleteOldFileOnStartup="Boolean"
enableFileDelete="Boolean"
createDirs="Boolean"
concurrentWrites="Boolean"
openFileCacheTimeout="Integer"
openFileCacheSize="Integer"
networkWrites="Boolean"
concurrentWriteAttemptDelay="Integer"
concurrentWriteAttempts="Integer"
bufferSize="Integer"
autoFlush="Boolean"
keepFileOpen="Boolean" />
</targets>
控制台
class Program
{
static void Main(string[] args)
{
NLog.Logger log = NLog.LogManager.GetCurrentClassLogger();
log.Debug("记录一个错误日志");
Console.WriteLine("执行完毕");
Console.ReadKey();
}
}