Microsoft.Framework.Logging.NLog
使用Nlog扩展日志系统：按照我们上节说的，对于扩展的日志系统都要实现俩个接口ILogger、ILoggerProvider。所以在当前工程中也没例外，NLogLoggerProvider实现了ILoggerProvider、内部类Logger实现了ILogger。源代码如下：
public class NLogLoggerProvider : ILoggerProvider
{
private readonly LogFactory _logFactory; public NLogLoggerProvider(LogFactory logFactory)
{
_logFactory = logFactory;
} public ILogger CreateLogger(string name)
{
return new Logger(_logFactory.GetLogger(name));
} private class Logger : ILogger
{
private readonly global::NLog.Logger _logger; public Logger(global::NLog.Logger logger)
{
_logger = logger;
} public void Log(
LogLevel logLevel,
int eventId,
object state,
Exception exception,
Func<object, Exception, string> formatter)
{
var nLogLogLevel = GetLogLevel(logLevel);
var message = string.Empty;
if (formatter != null)
{
message = formatter(state, exception);
}
else
{
message = LogFormatter.Formatter(state, exception);
}
if (!string.IsNullOrEmpty(message))
{
var eventInfo = LogEventInfo.Create(nLogLogLevel, _logger.Name, message, exception);
eventInfo.Properties["EventId"] = eventId;
_logger.Log(eventInfo);
}
} public bool IsEnabled(LogLevel logLevel)
{
return _logger.IsEnabled(GetLogLevel(logLevel));
} private global::NLog.LogLevel GetLogLevel(LogLevel logLevel)
{
switch (logLevel)
{
case LogLevel.Verbose: return global::NLog.LogLevel.Debug;
case LogLevel.Information: return global::NLog.LogLevel.Info;
case LogLevel.Warning: return global::NLog.LogLevel.Warn;
case LogLevel.Error: return global::NLog.LogLevel.Error;
case LogLevel.Critical: return global::NLog.LogLevel.Fatal;
}
return global::NLog.LogLevel.Debug;
} public IDisposable BeginScopeImpl([NotNull] object state)
{
return NestedDiagnosticsContext.Push(state.ToString());
}
}
}
NLog
这段代码很容易读懂，也就不过多解释了，需要注意的一点是：LogFactory是NLog的工厂。
下面我们主要就NLog和大名鼎鼎的Log4net进行比较（道听途说比较多，欢迎指正）
- 都不建议直接使用，使用门面类包装（也就是相当于本处的Microsoft.Framework.Logging.NLog的内部Logger类实际是Nlog的log的门面）
- 如果现在系统使用了日志系统，建议使用原有的日志系统（应用log4net比较多），完全新的项目建议使用Nlog
- 从初始化配置上看Nlog要比log4net简单
- 从功能强大度上，基本可以平分秋色
- 从开源代码更新程度上看：Nlog以及在github上开源（https://github.com/nlog）、log4net在Apache上开源（http://logging.apache.org/log4net/download_log4net.cgi）。但是Nlog还有更新，支持的.net版本也比较多；log4net感觉好久没更新了，核心版本还是.net2.0(此处不是道听途说，是楼猪自己下载源码得倒的结论)
- 据说使用同步记录日志时log4net比Nlog要快，但是Nlog可以开启异步记录，并且速度会反超log4net
下面是楼主参考的一些博文
- log4net vs. Nlog [closed]（骄傲的豹子）
- NLog 2.0.0.2000 使用实例 （回复部分为主要参考，主体是介绍Nlog的使用的）
- NLog文章系列——系列文章目录以及简要介绍（Nlog学习的参考）
测试代码：
<?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"
autoReload="true"> <targets>
<target name="logfile"
xsi:type="File"
fileName="file.txt"
layout="${longdate}|${level:uppercase=true}|${logger}|${event-context:item=EventId}|${message}|${ndc}" />
<target name="console"
xsi:type="ColoredConsole"
layout="[${level:uppercase=true}:${logger}] ${message}"/>
</targets> <rules>
<logger name="*" minlevel="Info" writeTo="logfile,console" />
</rules>
</nlog>
public Program()
{
// a DI based application would get ILoggerFactory injected instead
var factory = new LoggerFactory(); // getting the logger immediately using the class's name is conventional
_logger = factory.CreateLogger(typeof(Program).FullName); // providers may be added to an ILoggerFactory at any time, existing ILoggers are updated
#if !DNXCORE50
factory.AddNLog(new global::NLog.LogFactory());
#endif
factory.AddConsole();
factory.AddConsole((category, logLevel) => logLevel >= LogLevel.Critical && category.Equals(typeof(Program).FullName));
}
Microsoft.Framework.Logging.Console
实际上用控制台直接写日志的并不多，所以这个日志系统可能用途并不广，不过精炼的代码还是有很多可圈可点的地方：使用IConsole接口以及LogConsole类。我们一般来说肯定只会实现ILogger、ILoggerProvider俩个接口，也就是写实现类ConsoleLogger、ConsoleLoggerProvider。但是我们主要到ConsoleLogger只是负责记录的逻辑操作，具体对于介质的操作属于IConsole的职责，如果将ConsoleLogger与LogConsole柔和在一起，问题也不大；但是明显违反了面向对象设计的单一职责原则。所以麻雀虽小，五脏俱全，这几个小类也能体现面向对象的能力的。
Microsoft.Framework.Logging.TraceSource
这个对于我来说是个陌生的东西，虽然是.net自带的，并且从1.0就有了。最开始使用的时Debug和Trace进行跟踪、记录，到.net2.0时，使用TraceSource作为Debug和Trace的增强版本。
TraceSource的配置：
- Listeners：控制跟踪信息输出的方向（可以是：TextWriterTraceListener，DefaultTraceListener，EventLogTraceListener，WebPageTraceListener等，而TextWriterTraceListener的子类又有ConsoleTraceListener， DelimitedListTraceListener，XmlWriterTraceListener，EventSchemaTraceListener）
- Switch：筛选信息的开关，主要包括BooleanSwitch 类、TraceSwitch 类和 SourceSwitch 类
主要参考的文献：
我们回头看Microsoft.Framework.Logging.TraceSource代码，也就一目了然了.
public class TraceSourceLoggerProvider : ILoggerProvider
{
private readonly SourceSwitch _rootSourceSwitch;
private readonly TraceListener _rootTraceListener; private readonly ConcurrentDictionary<string, TraceSource> _sources = new ConcurrentDictionary<string, TraceSource>(StringComparer.OrdinalIgnoreCase); public TraceSourceLoggerProvider([NotNull]SourceSwitch rootSourceSwitch, [NotNull]TraceListener rootTraceListener)
{
_rootSourceSwitch = rootSourceSwitch;
_rootTraceListener = rootTraceListener;
} public ILogger CreateLogger(string name)
{
return new TraceSourceLogger(GetOrAddTraceSource(name));
} private TraceSource GetOrAddTraceSource(string name)
{
return _sources.GetOrAdd(name, InitializeTraceSource);
} private TraceSource InitializeTraceSource(string traceSourceName)
{
var traceSource = new TraceSource(traceSourceName);
string parentSourceName = ParentSourceName(traceSourceName); if (string.IsNullOrEmpty(parentSourceName))
{
if (HasDefaultSwitch(traceSource))
{
traceSource.Switch = _rootSourceSwitch;
} if (_rootTraceListener != null)
{
traceSource.Listeners.Add(_rootTraceListener);
}
}
else
{
if (HasDefaultListeners(traceSource))
{
TraceSource parentTraceSource = GetOrAddTraceSource(parentSourceName);
traceSource.Listeners.Clear();
traceSource.Listeners.AddRange(parentTraceSource.Listeners);
} if (HasDefaultSwitch(traceSource))
{
TraceSource parentTraceSource = GetOrAddTraceSource(parentSourceName);
traceSource.Switch = parentTraceSource.Switch;
}
} return traceSource;
} private static string ParentSourceName(string traceSourceName)
{
int indexOfLastDot = traceSourceName.LastIndexOf('.');
return indexOfLastDot == - ? null : traceSourceName.Substring(, indexOfLastDot);
} private static bool HasDefaultListeners(TraceSource traceSource)
{
return traceSource.Listeners.Count == && traceSource.Listeners[] is DefaultTraceListener;
} private static bool HasDefaultSwitch(TraceSource traceSource)
{
return string.IsNullOrEmpty(traceSource.Switch.DisplayName) == string.IsNullOrEmpty(traceSource.Name) &&
traceSource.Switch.Level == SourceLevels.Off;
}
}
TraceSourceLoggerProvider
internal class TraceSourceLogger : ILogger
{
private readonly TraceSource _traceSource; public TraceSourceLogger(TraceSource traceSource)
{
_traceSource = traceSource;
} public void Log(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter)
{
if (!IsEnabled(logLevel))
{
return;
}
var message = string.Empty;
if (formatter != null)
{
message = formatter(state, exception);
}
else
{
if (state != null)
{
message += state;
}
if (exception != null)
{
message += Environment.NewLine + exception;
}
}
if (!string.IsNullOrEmpty(message))
{
_traceSource.TraceEvent(GetEventType(logLevel), eventId, message);
}
} public bool IsEnabled(LogLevel logLevel)
{
var traceEventType = GetEventType(logLevel);
return _traceSource.Switch.ShouldTrace(traceEventType);
} private static TraceEventType GetEventType(LogLevel logLevel)
{
switch (logLevel)
{
case LogLevel.Critical: return TraceEventType.Critical;
case LogLevel.Error: return TraceEventType.Error;
case LogLevel.Warning: return TraceEventType.Warning;
case LogLevel.Information: return TraceEventType.Information;
case LogLevel.Verbose:
default: return TraceEventType.Verbose;
}
} public IDisposable BeginScopeImpl(object state)
{
return new TraceSourceScope(state);
}
}
TraceSourceLogger
[Fact]
public static void IsEnabledReturnsCorrectValue()
{
// Arrange
var testSwitch = new SourceSwitch("TestSwitch", "Level will be set to warning for this test");
testSwitch.Level = SourceLevels.Warning; var factory = new LoggerFactory();
var logger = factory.CreateLogger("Test"); // Act
factory.AddTraceSource(testSwitch, new ConsoleTraceListener()); // Assert
Assert.True(logger.IsEnabled(LogLevel.Critical));
Assert.True(logger.IsEnabled(LogLevel.Error));
Assert.True(logger.IsEnabled(LogLevel.Warning));
Assert.False(logger.IsEnabled(LogLevel.Information));
Assert.False(logger.IsEnabled(LogLevel.Verbose));
} [Theory]
[InlineData(SourceLevels.Warning, SourceLevels.Information, true)]
[InlineData(SourceLevels.Information, SourceLevels.Information, true)]
[InlineData(SourceLevels.Information, SourceLevels.Warning, true)]
[InlineData(SourceLevels.Warning, SourceLevels.Warning, false)]
public static void MultipleLoggers_IsEnabledReturnsCorrectValue(SourceLevels first, SourceLevels second, bool expected)
{
// Arrange
var firstSwitch = new SourceSwitch("FirstSwitch", "First Test Switch");
firstSwitch.Level = first; var secondSwitch = new SourceSwitch("SecondSwitch", "Second Test Switch");
secondSwitch.Level = second; var factory = new LoggerFactory();
var logger = factory.CreateLogger("Test"); // Act
factory.AddTraceSource(firstSwitch, new ConsoleTraceListener());
factory.AddTraceSource(secondSwitch, new ConsoleTraceListener()); // Assert
Assert.Equal(expected, logger.IsEnabled(LogLevel.Information));
}
}