public TokenRefreshService(ILogger<TokenRefreshService> logger)
        {
            _logger = logger;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            _logger.LogInformation("Service starting");
           //************
        }

<?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"
      throwConfigExceptions="true"
      internalLogLevel="info"
      internalLogFile="d:\log\internal-nlog.txt">


  <!-- the targets to write to -->
  <targets>
    <!-- write logs to file  -->
    <target xsi:type="File" name="allfile" fileName="d:\log\nlog-all-${shortdate}.log"
            layout="${longdate}|${event-properties:item=EventId_Id:whenEmpty=0}|${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="d:\log\nlog-own-${shortdate}.log"
            layout="${longdate}|${event-properties:item=EventId_Id:whenEmpty=0}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}|${callsite}" />
  </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 -->
    <logger name="*" minlevel="Trace" writeTo="ownFile-web" />
  </rules>
</nlog>

 1     public class Program
    {
        public static void Main(string[] args)
        {
            NLog.Web.NLogBuilder.ConfigureNLog("nlog1.config");  //假如沒有用默認的名字，多寫了一個1
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .ConfigureLogging(logging =>
                {
                    logging.ClearProviders(); //移除已經注冊的其他日志處理程序
                    logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace); //設置最小的日志級別
                })
                .UseNLog();  
    }

1 logger.LogTrace();
logger.LogDebug();
logger.LogInformation();
logger.LogWarning();
logger.LogError();
logger.LogCritical();