快速了解如何在.NETCORE中使用Generic-Host建立主机

public interface IHostBuilder
{
 IHost Build();

 IHostBuilder ConfigureAppConfiguration(Action<HostBuilderContext, IConfigurationBuilder> configureDelegate);

 IHostBuilder ConfigureContainer<TContainerBuilder>(Action<HostBuilderContext, TContainerBuilder> configureDelegate);

 IHostBuilder ConfigureHostConfiguration(Action<IConfigurationBuilder> configureDelegate);

 IHostBuilder ConfigureServices(Action<HostBuilderContext, IServiceCollection> configureDelegate);
 
 IHostBuilder UseServiceProviderFactory<TContainerBuilder>(IServiceProviderFactory<TContainerBuilder> factory);
}

static void Main(string[] args)
{
 CreateDefaultHost(args).Build().Run();
}static IHostBuilder CreateDefaultHost(string[] args) => new HostBuilder()
 .ConfigureHostConfiguration(builder =>
 {  //todo
 })
 .ConfigureAppConfiguration((ctx, builder) =>
 {
  builder
   .SetBasePath(AppContext.BaseDirectory)
   .AddJsonFile("appsettings.json", true, true)
   .AddJsonFile($"appsettings.{ctx.HostingEnvironment.EnvironmentName}.json", true, true)
   .AddEnvironmentVariables()
   ;
 })
 .ConfigureServices((ctx, services) =>
 {
  services.AddLogging();
  services.AddHostedService<CustomHostService>();
 })
 .UseConsoleLifetime()
 ;

public class CustomHostService: IHostedService{ private ILogger _logger; private Task _executingTask; public Task StartAsync(...) {
  _logger.LogInformation($"{nameof(CustomHostService):}start");

  _executingTask = ExecuteAsync(...);  if(_executingTask.IsCompleted){   return _executingTask;
  }  return Task.CompletedTask;
 } public Task StopAsync(CancellationToken cancellationToken) {  return Task.WhenAny(_executingTask, Task.Delay(Timeout.Infinite, cancellationToken));
 } public Task ExecuteAsync(...) {
  _logger.LogInformation($"{nameof(CustomHostService):executing}")  return Task.Delay(5000);
 }

}

new HostBuilder()
 .UseContentRoot(...)
 .UseEnvironment(...) ...

new HostBuilder().ConfigureHostConfiguration(builder =>
 {
  builder.AddInMemoryCollection(new Dictionary<string, string>
  {
   [HostDefaults.EnvironmentKey] = Environment.GetEnvironmentVariable("DOTNETCORE_ENVIRONMENT"),
  })  // Nuget:Microsoft.Extensions.Configuration.CommandLine
  //.AddCommandLine(args) 
  ;
 }) 
 //...

Install-Package Microsoft.Extensions.Configuration.CommandLine

Install-Package Autofac

Install-Package Autofac.Extensions.DependencyInection

//省略了非关键代码static IHostBuilder CreateDefaultHost(string[] args) => new HostBuilder()//...略
 .ConfigureServices((ctx, services) =>
 {
  services.AddLogging(x=>{x.AddConsole();});

  services.AddAutofac();
 })
 .ConfigureContainer<ContainerBuilder>(builder => 
 {
  builder.RegisterType<CustomHostService>()
  .As<IHostedService>()
  .InstancePerDependency();
 })   
 .UseServiceProviderFactory<ContainerBuilder>(new AutofacServiceProviderFactory())//...略