参考链接：https://github.com/NLog/NLog/wiki/Getting-started-with-ASP.NET-Core-3

参考链接：https://www.cnblogs.com/fancyblogs/p/12924263.html

1、引用程序集，添加Nlog包

安装或更新到最新Nlog包:

    NLog.Web.AspNetCore 4.9+

2、创建一个nlog.config 配置文件

案例

<?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"

      internalLogLevel="Info"

      internalLogFile="c:\temp\internal-nlog.txt">

  <!-- enable asp.net core layout renderers -->

  <extensions>

    <add assembly="NLog.Web.AspNetCore"/>

  </extensions>

  <!-- the targets to write to -->

  <targets>

    <!-- write logs to file  -->

    <target xsi:type="File" name="allfile" fileName="c:\temp\nlog-all-${shortdate}.log"

            layout="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}" />

    <!-- another file log, only own logs. Uses some ASP.NET core renderers -->

    <target xsi:type="File" name="ownFile-web" fileName="c:\temp\nlog-own-${shortdate}.log"

            layout="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}" />

  </targets>

  <!-- rules to map from logger name to target -->

  <rules>

    <!--All logs, including from Microsoft-->

    <logger name="*" minlevel="Trace" writeTo="allfile" />

    <!--Skip non-critical Microsoft logs and so log only own logs-->

    <logger name="Microsoft.*" maxlevel="Info" final="true" /> <!-- BlackHole without writeTo -->

    <logger name="*" minlevel="Trace" writeTo="ownFile-web" />

  </rules>

</nlog>

3、设置nlog.config属性为“如果较新则复制”

4、修改Program.cs 注入, UseNLog()

using System;using NLog.Web;using Microsoft.AspNetCore.Hosting;using Microsoft.Extensions.Logging;using Microsoft.Extensions.Hosting;

public static void Main(string[] args)

{

    var logger = NLog.Web.NLogBuilder.ConfigureNLog("nlog.config").GetCurrentClassLogger();

    try

    {

        logger.Debug("init main");

        CreateHostBuilder(args).Build().Run();

    }

    catch (Exception exception)

    {

        //NLog: catch setup errors

        logger.Error(exception, "Stopped program because of exception");

        throw;

    }

    finally

    {

        // Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux)

        NLog.LogManager.Shutdown();

    }

}

public static IHostBuilder CreateHostBuilder(string[] args) =>

    Host.CreateDefaultBuilder(args)

      .ConfigureWebHostDefaults(webBuilder =>

      {

          webBuilder.UseStartup<Startup>();

      })

      .ConfigureLogging(logging =>

      {

          logging.ClearProviders();

          logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);

      })

      .UseNLog();  // NLog: Setup NLog for Dependency injection

5、配置 appsetting.json

{

  "Logging": {

    "IncludeScopes": false,

    "LogLevel": {

      "Default": "Trace",

      "Microsoft": "Warning",

      "Microsoft.Hosting.Lifetime": "Information"

    }

  },

  "AllowedHosts": "*"

}

6、使用日志

 
using Microsoft.Extensions.Logging;
public class HomeController : Controller
{
    private readonly ILogger<HomeController> _logger;
    public HomeController(ILogger<HomeController> logger)
    {
        _logger = logger;
        _logger.LogDebug(1, "NLog injected into HomeController");
    }
    public IActionResult Index()
    {
        _logger.LogInformation("Hello, this is the index!");
        return View();
    }

7、输出日志文件

8、封装

可以将Nlog的使用封装在一个类中，方便调用

using System;
using System.Collections.Generic;
using System.Text;
using NLog;
namespace App.Common.Log
{
    /// <summary>
    /// 日志
    /// </summary>
   public class NLogger
    {
        private static Logger logger;
        static NLogger()
        {
            logger = LogManager.GetCurrentClassLogger();
            logger = logger.Factory.GetLogger("*");  }
        /// <summary>
        /// 记录调试信息
        /// </summary>
        /// <param name="info">日志信息</param>

        public static void Debug(string info)
        {
            logger.Debug(info);
        }

        /// <summary>
        /// 记录信息
        /// </summary>
        /// <param name="info">日志信息</param>
        public static void Info(string info)
        {
            logger.Info(info);
        }

        /// <summary>
        /// 记录警告信息
        /// </summary>
        /// <param name="info">日志信息</param>
        public static void Warn(string info)
        {
            logger.Info(info);
        }

        /// <summary>
        /// 记录异常信息
        /// </summary>
        /// <param name="exception">异常</param>
        public static void Error(Exception exception)
        {
            logger.Error(GetExceptionFullMessage(exception));
        }


        /// <summary>
        /// 记录致命错误
        /// </summary>
        /// <param name="info">错误信息</param>
        public static void Fatal(string info)
        {
            logger.Fatal(info);
        }

        /// <summary>
        /// 获取完整的异常消息，包括内部异常消息
        /// </summary>
        /// <param name="exception"></param>
        /// <returns></returns>
        internal static string GetExceptionFullMessage (Exception exception)
        {
            if(exception==null)
            {
                return null;
            }
            var message = new StringBuilder(exception.Message);
            var innerException = exception.InnerException;
            while(innerException!=null)
            {
                message.Append("--->");
                message.Append(innerException.Message);
                innerException = innerException.InnerException;
            }
            return message.ToString();
        }
    }

9、使用方法

NLogger.Info("这是一个日志信息");