public static void Main(string[] args)
{
    var webHost = new WebHostBuilder()
        .UseKestrel()
        .UseContentRoot(Directory.GetCurrentDirectory())
        .ConfigureAppConfiguration((hostingContext, config) =>
        {
            var env = hostingContext.HostingEnvironment;
            config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                  .AddJsonFile($"appsettings.{env.EnvironmentName}.json",
                      optional: true, reloadOnChange: true);
            config.AddEnvironmentVariables();
        })
        .ConfigureLogging((hostingContext, logging) =>
        {
            //添加appsettings.json中關(guān)于日志的Logging節(jié)點配置
            logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
            //日志控制臺記錄提供程序
            logging.AddConsole();
            //日志Debug記錄提供程序
logging.AddDebug();
            //日志EventSource記錄提供程序
logging.AddEventSourceLogger();
        })
        .UseStartup<Startup>()
        .Build();
    webHost.Run();
}

public static void Main(string[] args)
{
    CreateWebHostBuilder(args).Build().Run();
}
public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
        .UseStartup<Startup>();

public class AboutModel
{
    private readonly ILogger _logger;
    public AboutModel(ILogger<AboutModel> logger)
　{
  　 //ILogger是Core內(nèi)置日志組件，默認已經(jīng)注入，無需再次手動注入
        _logger = logger;
    }
    public void OnGet()
    {
        var Message = $"About page visited at {DateTime.UtcNow.ToLongTimeString()}";
        _logger.LogInformation("Message displayed: {Message}", Message);
    }
}
private readonly ILogger<AboutModel> _logger;
public HomeController(ILogger<AboutModel> logger)
{
    _logger = logger;
}
public IActionResult Index()
{
    AboutModel aboutModel = new AboutModel(_logger);
    aboutModel.OnGet();
    return View();
}

public class Startup
{
    private readonly ILogger _logger;
    public Startup(IConfiguration configuration, ILogger<Startup> logger)
    {
        Configuration = configuration;
        _logger = logger;
    }
    public IConfiguration Configuration { get; }
    public void ConfigureServices(IServiceCollection services)
    {
        _logger.LogInformation("Added TodoRepository to services");
    }
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            _logger.LogInformation("In Development environment");
        }
    }
}

public class Program
{
    public static void Main(string[] args)
    {
        var host = CreateWebHostBuilder(args).Build();
        var logger = host.Services.GetRequiredService<ILogger<Program>>();
        logger.LogInformation("Seeded the database.");
        host.Run();
    }
    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
    .UseStartup<Startup>()
    .ConfigureLogging(logging =>
    {
        logging.ClearProviders();
        logging.AddConsole();
    });
}

{
  "Logging": {
    "LogLevel": {
      "Default": "Debug",
      "System": "Information",
      "Microsoft": "Information"
    },
    "Console":
    {
      "IncludeScopes": true
    }
  }
}