public async Task StartAsync(CancellationToken cancellationToken = default (CancellationToken)){this._logger.Starting();TaskCompletionSource<object> completionSource1 = new TaskCompletionSource<object>();ref CancellationToken local = ref cancellationToken;TaskCompletionSource<object> completionSource2 = completionSource1;local.Register((Action<object>) (obj => ((TaskCompletionSource<object>) obj).TrySetCanceled()), (object) completionSource2);IHostLifetime hostLifetime1 = this._hostLifetime;TaskCompletionSource<object> completionSource3 = completionSource1;hostLifetime1.RegisterDelayStartCallback((Action<object>) (obj => ((TaskCompletionSource<object>) obj).TrySetResult((object) null)), (object) completionSource3);IHostLifetime hostLifetime2 = this._hostLifetime;ApplicationLifetime applicationLifetime = this._applicationLifetime;hostLifetime2.RegisterStopCallback((Action<object>) (obj => (obj as IApplicationLifetime)?.StopApplication()), (object) applicationLifetime);object task = await completionSource1.Task;

this._hostedServices = this.Services.GetService<IEnumerable<IHostedService>>(); foreach (IHostedService hostedService in this._hostedServices) await hostedService.StartAsync(cancellationToken).ConfigureAwait(false

);this._applicationLifetime?.NotifyStarted();this._logger.Started();}

public class PrintTextToConsoleService : IHostedService, IDisposable{private readonly ILogger _logger;private readonly IOptions<AppConfig> _appConfig;private Timer _timer;public PrintTextToConsoleService(ILogger<PrintTextToConsoleService> logger, IOptions<AppConfig> appConfig){_logger = logger;_appConfig = appConfig;}public Task StartAsync(CancellationToken cancellationToken){_logger.LogInformation("Starting");_timer = new Timer(DoWork, null, TimeSpan.Zero,TimeSpan.FromSeconds(5));return Task.CompletedTask;}private void DoWork(object state){_logger.LogInformation($"Background work with text: {_appConfig.Value.TextToPrint}");}public Task StopAsync(CancellationToken cancellationToken){_logger.LogInformation("Stopping.");_timer?.Change(Timeout.Infinite, 0);return Task.CompletedTask;}public void Dispose(){_timer?.Dispose();}}

public static async Task Main(string[] args){var builder = new HostBuilder()    //实例化一个通用主机.ConfigureAppConfiguration((hostingContext, config) =>{config.AddJsonFile("appsettings.json", optional: true);config.AddEnvironmentVariables();if (args != null){config.AddCommandLine(args);}}) //配置Configuration.ConfigureServices((hostContext, services) =>{services.AddOptions();services.Configure<AppConfig>(hostContext.Configuration.GetSection("AppConfig"));services.AddSingleton

<IHostedService, PrintTextToConsoleService>

();})    //配置Service （依赖注入）.ConfigureLogging((hostingContext, logging) => {logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));logging.AddConsole();});   //配置Log （本项目中要利用Log把内容在控制台输出）await builder.RunConsoleAsync();    //在控制台应用程序中运行通用主机}