[Asp.net 5] Logging-其他日志系统的实现

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

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 == -1 ? null : traceSourceName.Substring(0, indexOfLastDot);
        }

        private static bool HasDefaultListeners(TraceSource traceSource)
        {
            return traceSource.Listeners.Count == 1 && traceSource.Listeners[0] 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));
        }
    }
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原文地址：https://www.cnblogs.com/watermoon2/p/4554808.html