. Net how to use log framework NLog

.Net How to use the log framework NLog

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stay Nuget Install in NLog

NLog You can use it directly Nuget install ：PM > Install-Package Nlog

Use NLog

NLog Is basically the same as other Log The library is almost , It is divided into Trace、Debug、Info、Error、Fatal Five levels

    private static Logger logger = LogManager.GetCurrentClassLogger();    static void Main(string[] args)    {        logger.Trace("Trace Message");        logger.Debug("Debug Message");        logger.Info("Info Message");        logger.Error("Error Message");        logger.Fatal("Fatal Message");    }

But it provides a lot of methods , light Trace There is 42 Heavy duty . Although powerful events are good , But it also increases the learning cost to some extent .

To configure NLog

After executing the above statement , In fact, it has no effect . Because we haven't configured the log output path yet . This output path is usually configured in the configuration file （ Hard coding is also supported ）,NLog Two configuration file formats are supported

• Configuration information is embedded in .NET Application standard *.exe.config perhaps web.config In the document

• Saved in a separate file , Also called single format

The first one is more conventional , But I don't like this way , Because it is written together with other log independent configurations , It is not convenient to share configurations among different projects . Here we mainly introduce the way of independent files .NLog Configuration files with the following three file names are supported ："NLog.config"、"*.exe.nlog" and "NLog.dll.nlog", I prefer the first one . Either way , The content is the same , A simple example is as follows ：

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">    <targets>        <target name="console" xsi:type="Console" />        <target name="debugger" xsi:type="Debugger" layout="${date:format=HH\:mm\:ss.fff}: ${message}" />        <target name="error_file" xsi:type="File"                        fileName="${basedir}/Logs/Error/${shortdate}/error.txt" maxArchiveFiles="30"                        layout="${longdate} | ${level:uppercase=false} | ${message} ${onexception:${exception:format=tostring} ${newline} ${stacktrace} ${newline}" />    </targets>    <rules>        <!--<logger name="*" writeTo="console" />-->        <logger name="*" minlevel="Debug" writeTo="debugger" />        <logger name="*" minlevel="Error" writeTo="error_file" />    </rules></nlog>

It mainly consists of two parts ： Output target target and Routing rules rule. Let's introduce them respectively .

Output target target

Every target Represents an output target , It mainly contains two properties ：name and type.name Is the name of the output template , Use in the following routing rules ,type Is the output type , Common are

• Console         Output to console

• Debugger     Output to

• File         output to a file

• Mail         The output is sent by mail

• Network         Output to network address

• Database         Output to database

When choosing a certain type , You also need to configure the corresponding parameters . If the output type is File when , We need to configure the log path filename, Here are some variables that can be used （ Inside the curly brackets ）, My example here ：

fileName="${basedir}/Logs/Error/${shortdate}/error.txt"

The output log format is /Log/2014-10-01/err.txt     Generate a folder every day , Very convenient .

Control of output format ：

sometimes , We need time to 、 The output format of these objects, such as exceptions, is controlled . They can be modified layout Parameter to implement . This part is relatively complicated , Beyond the scope of this article , I'd like to make a special introduction if I have time .

By the way, I also post a configuration document that I often use ：

<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">    <targets>        <!-- Screen print message -->        <target name="console" xsi:type="ColoredConsole"                        layout="${date:format=HH\:mm\:ss}> ${message}"/>                <!--VS Output window -->        <target name="debugger" xsi:type="Debugger"                        layout="${date:format=HH\:mm\:ss} | ${level:padding=-5} | ${message}" />        <!-- Save to file -->        <target name="error_file" xsi:type="File" maxArchiveFiles="30"                        fileName="${basedir}/Logs/Error/${shortdate}/error.txt"                        layout="${longdate} | ${level:uppercase=false:padding=-5} | ${message} ${onexception:${exception:format=tostring} ${newline} ${stacktrace} ${newline}" />    </targets>    <rules>        <!--<logger name="*" writeTo="console" />-->        <logger name="*" minlevel="Debug" writeTo="debugger" />        <logger name="*" minlevel="Error" writeTo="error_file" />    </rules></nlog>

Routing rules rule

Routing rules are mainly used to match logs with output targets , It generally has the following properties

• name - Name of recorder ( Wildcards are allowed *)

• minlevel - Match the lowest level of log range

• maxlevel - Match the highest level of log range

• level - Matching single log level

• levels - A series of matching log levels , Separated by commas .

• writeTo - A set of targets that the log should be written to when the rules match , Separated by commas .

There seem to be several properties , In fact, it is relatively simple to use , For example, my previous three rules are explained as follows ：

    <logger name="*" writeTo="console" />     Output all logs to the console     <logger name="*" minlevel="Debug" writeTo="debugger" />             take Debug Logs above level are output to Debugger in     <logger name="*" minlevel="Error" writeTo="error_file" />         take Error Logs above level are output to a file 

in addition ,NLOG Support to configure multiple routing rules , It is very convenient for our output .

Simple encapsulation ：

We have already listed NLog How to use , Although its use is not miscellaneous , But a simple Wrapper It can lower the threshold of use , Standardize the way of use , It is even convenient to switch the logging framework later , It is very necessary in many cases . Here is a simple package ：

    class Logger    {        NLog.Logger logger;        private Logger(NLog.Logger logger)        {            this.logger = logger;        }        public Logger(string name)            :this(NLog.LogManager.GetLogger(name))        {        }        public static Logger Default { get; private set; }        static Logger()        {            Default = new Logger(NLog.LogManager.GetCurrentClassLogger());        }        public void Debug(string msg, params object[] args)        {            logger.Debug(msg, args);        }        public void Debug(string msg, Exception err)        {            logger.Debug(msg, err);        }        public void Info(string msg, params object[] args)        {            logger.Info(msg, args);        }        public void Info(string msg, Exception err)        {            logger.Info(msg, err);        }        public void Trace(string msg, params object[] args)        {            logger.Trace(msg, args);        }        public void Trace(string msg, Exception err)        {            logger.Trace(msg, err);        }        public void Error(string msg, params object[] args)        {            logger.Error(msg, args);        }        public void Error(string msg, Exception err)        {            logger.Error(msg, err);        }        public void Fatal(string msg, params object[] args)        {            logger.Fatal(msg, args);        }        public void Fatal(string msg, Exception err)        {            logger.Fatal(msg, err);        }    }

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