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NLog是一个记录日志组件，和log4net一样被广泛使用，它可以将日志保存到文本文件、CSV、控制台、VS调试窗口、数据库等。最近刚用到这个组件，觉得不错，水一篇。
下载
通过Nuget安装NLog，你也可以同时安装NLog.Config，它会在项目目录下帮你建立一个配置文件NLog.config，不过不需要，我们直接手动建立一个，你也可以将配置的信息写入到 App.config/Web.config，我比较喜欢独立出来，不与其它配置掺和在一起。
配置
在项目根目录下新建一个NLog.config，基本目录结构：targets下面配置日志输出目标及相关参数，rules下面配置目标输出规则。
<?xml version="1.0" ?> <nlog> <targets> <target></target> <target></target> </targets> <rules> <logger></logger> <logger></logger> </rules> </nlog>
记得在NLog.config的属性中设置 Copy to Output Directory: Copy always
现在我们要将日志输出到文本文件，数据库，VS调试窗口，完整配置文件如下：
<?xml version="1.0" ?> <!--<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" autoReload="true" internalLogLevel="Trace" internalLogFile="D:\work\log.txt">--> <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" autoReload="true"> <targets> <!-- Log in a separate thread, possibly queueing up to 5000 messages. When the queue overflows, discard any extra messages--> <!-- write logs to file --> <target name="file" xsi:type="AsyncWrapper" queueLimit="5000" overflowAction="Discard"> <target xsi:type="File" fileName="${basedir}/logs/${shortdate}.log" layout="${longdate} ${level:uppercase=true} ${event-context:item=Action} ${message} ${event-context:item=Amount} ${stacktrace}" /> </target> <!-- write log message to database --> <target name="db" xsi:type="AsyncWrapper" queueLimit="5000" overflowAction="Discard"> <target type="Database" dbProvider="mssql" connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=EFinance;Persist Security Info=True;User ID=sa;Password=123456;"> <commandText> INSERT INTO Log(Timestamp,Level,Message,Action,Amount,StackTrace) VALUES(@time_stamp, @level, @message, @action, @amount, @stacktrace); </commandText> <!-- database connection parameters --> <parameter name="@time_stamp" layout="${date}" /> <parameter name="@level" layout="${level:uppercase=true}" /> <parameter name="@message" layout="${message}" /> <parameter name="@action" layout="${event-context:item=Action}" /> <parameter name="@amount" layout="${event-context:item=Amount}" /> <parameter name="@stacktrace" layout="${stacktrace}" /> </target> </target> <!--write log message to Visual Studio Output--> <target name="debugger" xsi:type="Debugger" layout="NLog: ${date:format=HH\:mm\:ss} | ${level:uppercase=true:padding=-5} | ${message}" /> </targets> <rules> <!--TRACE,DEBUG,INFO,WARN,ERROR,FATAL--> <logger name="*" minlevel="Trace" writeTo="debugger" /> <!--INFO,WARN,ERROR,FATAL--> <logger name="*" minlevel="Info" writeTo="db" /> <!--DEBUG,INFO,WARN,ERROR,FATAL--> <logger name="*" minlevel="Debug" writeTo="file" /> </rules> </nlog>
封装
简单两句就可以使用NLog了：
NLog.Logger logger = Nlog.LogManager.GetCurrentClassLogger();
logger.Fatal("发生致命错误");
logger.Warn("警告信息");
但是这样只能记录了NLog的内置字段，我们定义的 Amount, Action都不能写入，接下来我们来封装一个Logger：
public class Logger { NLog.Logger _logger; private Logger(NLog.Logger logger) { _logger = logger; } public Logger(string name) : this(LogManager.GetLogger(name)) { } public static Logger Default { get; private set; } static Logger() { Default = new Logger(NLog.LogManager.GetCurrentClassLogger()); } #region Debug public void Debug(string msg, params object[] args) { _logger.Debug(msg, args); } public void Debug(string msg, Exception err) { _logger.Debug(err, msg); } #endregion #region Info public void Info(string msg, params object[] args) { _logger.Info(msg, args); } public void Info(string msg, Exception err) { _logger.Info(err, msg); } #endregion #region Warn public void Warn(string msg, params object[] args) { _logger.Warn(msg, args); } public void Warn(string msg, Exception err) { _logger.Warn(err, msg); } #endregion #region Trace public void Trace(string msg, params object[] args) { _logger.Trace(msg, args); } public void Trace(string msg, Exception err) { _logger.Trace(err, msg); } #endregion #region Error public void Error(string msg, params object[] args) { _logger.Error(msg, args); } public void Error(string msg, Exception err) { _logger.Error(err, msg); } #endregion #region Fatal public void Fatal(string msg, params object[] args) { _logger.Fatal(msg, args); } public void Fatal(string msg, Exception err) { _logger.Fatal(err, msg); } #endregion #region Custom public void Process(Models.Log log) { var level = LogLevel.Info; if (log.Level == Models.EFLogLevel.Trace) level = LogLevel.Trace; else if (log.Level == Models.EFLogLevel.Debug) level = LogLevel.Debug; else if (log.Level == Models.EFLogLevel.Info) level = LogLevel.Info; else if (log.Level == Models.EFLogLevel.Warn) level = LogLevel.Warn; else if (log.Level == Models.EFLogLevel.Error) level = LogLevel.Error; else if (log.Level == Models.EFLogLevel.Fatal) level = LogLevel.Fatal; var ei = new MyLogEventInfo(level, _logger.Name, log.Message); ei.TimeStamp = log.Timestamp; ei.Properties["Action"] = log.Action; ei.Properties["Amount"] = log.Amount; _logger.Log(level, ei); } #endregion /// <summary> /// Flush any pending log messages (in case of asynchronous targets). /// </summary> /// <param name="timeoutMilliseconds">Maximum time to allow for the flush. Any messages after that time will be discarded.</param> public void Flush(int? timeoutMilliseconds = null) { if (timeoutMilliseconds != null) NLog.LogManager.Flush(timeoutMilliseconds.Value); NLog.LogManager.Flush(); } } public class MyLogEventInfo : LogEventInfo { public MyLogEventInfo() { } public MyLogEventInfo(LogLevel level, string loggerName, string message) : base(level, loggerName, message) { } public override string ToString() { //Message format //Log Event: Logger=‘XXX‘ Level=Info Message=‘XXX‘ SequenceID=5 return FormattedMessage; } }
public class Log : IEntityBase<long> { public long Id { get; set; } /// <summary> /// 日志级别 Trace|Debug|Info|Warn|Error|Fatal /// </summary> public string Level { get; set; } public string Message { get; set; } public string Action { get; set; } public string Amount { get; set; } public string StackTrace { get; set; } public DateTime Timestamp { get; set; } private Log() { } public Log(string level, string message, string action = null, string amount = null) { this.Level = level; this.Message = message; this.Action = action; this.Amount = amount; } }
使用：
下面是测试方法，我们一共输出9条日志，这9条日志将输出到哪个目标，由配置文件中的Rules/logger决定
Logger.Default.Trace("Hello World! Trace"); Logger.Default.Info("Hello World! Info"); Logger.Default.Warn("Hello World! Warn"); Logger.Default.Debug("Hello World! Debug"); Logger.Default.Error("Hello World! Error"); Logger.Default.Fatal("Hello World! Fatal"); Logger.Default.Process(new Models.Log(Models.EFLogLevel.Info, "Hello World! Info", "TEST", "100.00")); Logger.Default.Process(new Models.Log(Models.EFLogLevel.Debug, "Hello World! Debug", "TEST", "100.00")); Logger.Default.Process(new Models.Log(Models.EFLogLevel.Error, "Hello World! Error", "TEST", "100.00"));
Logger.Default.Flush();
因为我们在Target中设置了异步，所以如果我们想当场看到输出结果，就需要使用Flush()方法，实际输出日志时就不需要了。
结果：
查看日志记录：
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原文地址：http://www.cnblogs.com/felixnet/p/5498759.html
