.NET Core 支援適用於各種內建和第三方日誌記錄提供程式的日誌記錄 API。先來看下如何將日誌記錄 API 與內建提供程式一起使用。

呼叫 CreateDefaultBuilder，這將新增以下日誌記錄提供程式：

• 控制檯

• 除錯

• EventSource

• EventLog：僅限 Windows

• public class Program
  {
      public static void Main(string[] args)
      {
          CreateHostBuilder(args).Build().Run();
      }
  
      public static
   
   IHostBuilder CreateHostBuilder(string[] args) =>
          Host.CreateDefaultBuilder(args)
              .ConfigureWebHostDefaults(webBuilder =>
              {
                  webBuilder.UseStartup<Startup>();
              });
  }

  若要替代Host.CreateDefaultBuilder 新增的預設日誌記錄提供程式集，請呼叫 ClearProviders 並新增所需的日誌記錄提供程式。例如，以下程式碼：

  • 呼叫 ClearProviders 以從生成器中刪除所有 ILoggerProvider 例項。

  • 新增控制檯日誌記錄提供程式。

  • public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureLogging(logging =>
            {
                logging.ClearProviders();
                logging.AddConsole();
            })
            .ConfigureWebHostDefaults(webBuilder 
     
    =>
            {
                webBuilder.UseStartup<Startup>();
            });

    使用第三方替代，以Nlog為例

    修改program.cs

  • 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

    寫日誌

  • 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();
        }