标签：amp   console   ase   txt   toc   win   keep   cep   statement   

Tutorial

This describes NLog for .NET Framework (.NET ver. 3.5 - 4.8) and .NET Core (NetStandard 1.3+)

NLog can be setup with the following steps:

1. Install NLog nuget package
2. Configure NLog Targets for output
3. Writing log messages

After having setup NLog, then make sure to explore:

• Layouts and LayoutRenderers
• Target Wrappers
• Best practices for using NLog

If something is not working as expected then check the Troubleshooting section.

If wanting to use Microsoft Extension Logging (MEL) then check .NET Core and ASP.NET.Core tutorials.

Configure NLog Targets for output

NLog will only produce output if having configured one (or more) NLog targets.

NLog can be configured using XML by adding a NLog.config file to your application project (File Properties: Copy If newer). NLog will automatically load the NLog.config by searching multiple file locations. This is a simple example of the content for NLog.config:

<?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">

    <targets>
        <target name="logfile" xsi:type="File" fileName="file.txt" />
        <target name="logconsole" xsi:type="Console" />
    </targets>

    <rules>
        <logger name="*" minlevel="Info" writeTo="logconsole" />
        <logger name="*" minlevel="Debug" writeTo="logfile" />
    </rules>
</nlog>

To configure programmatically, then one can do this in code:

var config = new NLog.Config.LoggingConfiguration();

// Targets where to log to: File and Console
var logfile = new NLog.Targets.FileTarget("logfile") { FileName = "file.txt" };
var logconsole = new NLog.Targets.ConsoleTarget("logconsole");
            
// Rules for mapping loggers to targets            
config.AddRule(LogLevel.Info, LogLevel.Fatal, logconsole);
config.AddRule(LogLevel.Debug, LogLevel.Fatal, logfile);
            
// Apply config           
NLog.LogManager.Configuration = config;

The rules redirects logger output to the wanted output targets. The rules also provides filtering options to output only relevant logevents. Usually based on logger-name and loglevel (Ex. name="*" minlevel="Trace" means everything).

See also Configuration File or Configure from code

See also Available NLog Targets for output.

Writing log messages

public static class Program
{
    private static readonly NLog.Logger Logger = NLog.LogManager.GetCurrentClassLogger();

    public void Main()
    {
        try
        {
           Logger.Info("Hello world");
           System.Console.ReadKey();
        }
        catch (Exception ex)
        {
           Logger.Error(ex, "Goodbye cruel world");
        }
    }
}  

The Logger can write messages with different LogLevels, which is used by the logging-rules (See minLevel in configuration example above) so only relevant messages are redirected to the wanted targets. The LogLevel identifies how important/detailed the message is. NLog can route log messages based primarily on their logger name and log level.

NLog supports the following log levels:

• Trace - very detailed logs, which may include high-volume information such as protocol payloads. This log level is typically only enabled during development
• Debug - debugging information, less detailed than trace, typically not enabled in production environment.
• Info - information messages, which are normally enabled in production environment
• Warn - warning messages, typically for non-critical issues, which can be recovered or which are temporary failures
• Error - error messages - most of the time these are Exceptions
• Fatal - very serious errors!

The logger is not tied to a specific target. The messages written to one logger can reach multiple targets based on the logging-rules configuration. Maintaining this separation lets you keep logging statements in your code and easily change how and where the logs are written, just by updating the configuration in one place. See also Filtering log messages.

NLog is also supported by many logging abstractions like Microsoft Extension Logging and LibLog.

NLog Tutorial

标签：amp   console   ase   txt   toc   win   keep   cep   statement   

原文地址：https://www.cnblogs.com/chucklu/p/13226034.html