.NET Core技术研究-主机Host

public static IHostBuilder CreateDefaultBuilder(string[] args)
        {
            var builder = new HostBuilder();
 
            builder.UseContentRoot(Directory.GetCurrentDirectory());
            builder.ConfigureHostConfiguration(config =>
            {
                config.AddEnvironmentVariables(prefix: "DOTNET_");
                if (args != null)
                {
                    config.AddCommandLine(args);
                }
            });
 
            builder.ConfigureAppConfiguration((hostingContext, config) =>
            {
                var env = hostingContext.HostingEnvironment;
 
                config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                      .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);
 
                if (env.IsDevelopment() && !string.IsNullOrEmpty(env.ApplicationName))
                {
                    var appAssembly = Assembly.Load(new AssemblyName(env.ApplicationName));
                    if (appAssembly != null)
                    {
                        config.AddUserSecrets(appAssembly, optional: true);
                    }
                }
 
                config.AddEnvironmentVariables();
 
                if (args != null)
                {
                    config.AddCommandLine(args);
                }
            })
            .ConfigureLogging((hostingContext, logging) =>
            {
                var isWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
 
                // IMPORTANT: This needs to be added *before* configuration is loaded, this lets
                // the defaults be overridden by the configuration.
                if (isWindows)
                {
                    // Default the EventLogLoggerProvider to warning or above
                    logging.AddFilter<EventLogLoggerProvider>(level => level >= LogLevel.Warning);
                }
 
                logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                logging.AddConsole();
                logging.AddDebug();
                logging.AddEventSourceLogger();
 
                if (isWindows)
                {
                    // Add the EventLogLoggerProvider on windows machines
                    logging.AddEventLog();
                }
            })
            .UseDefaultServiceProvider((context, options) =>
            {
                var isDevelopment = context.HostingEnvironment.IsDevelopment();
                options.ValidateScopes = isDevelopment;
                options.ValidateOnBuild = isDevelopment;
            });
 
            return builder;
        }

using System;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore;
 
namespace Microsoft.Extensions.Hosting
{
    /// <summary>
    /// Extension methods for configuring the IWebHostBuilder.
    /// </summary>
    public static class GenericHostBuilderExtensions
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="IWebHostBuilder"/> class with pre-configured defaults.
        /// </summary>
        /// <remarks>
        ///   The following defaults are applied to the <see cref="IWebHostBuilder"/>:
        ///     use Kestrel as the web server and configure it using the application‘s configuration providers,
        ///     adds the HostFiltering middleware,
        ///     adds the ForwardedHeaders middleware if ASPNETCORE_FORWARDEDHEADERS_ENABLED=true,
        ///     and enable IIS integration.
        /// </remarks>
        /// <param name="builder">The <see cref="IHostBuilder" /> instance to configure</param>
        /// <param name="configure">The configure callback</param>
        /// <returns>The <see cref="IHostBuilder"/> for chaining.</returns>
        public static IHostBuilder ConfigureWebHostDefaults(this IHostBuilder builder, Action<IWebHostBuilder> configure)
        {
            return builder.ConfigureWebHost(webHostBuilder =>
            {
                WebHost.ConfigureWebDefaults(webHostBuilder);
 
                configure(webHostBuilder);
            });
        }
    }
}
? 2020 GitHub, Inc.

using System;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
 
namespace Microsoft.Extensions.Hosting
{
    public static class GenericHostWebHostBuilderExtensions
    {
        public static IHostBuilder ConfigureWebHost(this IHostBuilder builder, Action<IWebHostBuilder> configure)
        {
            var webhostBuilder = new GenericWebHostBuilder(builder);
            configure(webhostBuilder);
            builder.ConfigureServices((context, services) => services.AddHostedService<GenericWebHostService>());
            return builder;
        }
    }
}

internal static void ConfigureWebDefaults(IWebHostBuilder builder)
       {
           builder.ConfigureAppConfiguration((ctx, cb) =>
           {
               if (ctx.HostingEnvironment.IsDevelopment())
               {
                   StaticWebAssetsLoader.UseStaticWebAssets(ctx.HostingEnvironment, ctx.Configuration);
               }
           });
           builder.UseKestrel((builderContext, options) =>
           {
               options.Configure(builderContext.Configuration.GetSection("Kestrel"));
           })
           .ConfigureServices((hostingContext, services) =>
           {
               // Fallback
               services.PostConfigure<HostFilteringOptions>(options =>
               {
                   if (options.AllowedHosts == null || options.AllowedHosts.Count == 0)
                   {
                       // "AllowedHosts": "localhost;127.0.0.1;[::1]"
                       var hosts = hostingContext.Configuration["AllowedHosts"]?.Split(new[] { ‘;‘ }, StringSplitOptions.RemoveEmptyEntries);
                       // Fall back to "*" to disable.
                       options.AllowedHosts = (hosts?.Length > 0 ? hosts : new[] { "*" });
                   }
               });
               // Change notification
               services.AddSingleton<IOptionsChangeTokenSource<HostFilteringOptions>>(
                           new ConfigurationChangeTokenSource<HostFilteringOptions>(hostingContext.Configuration));
 
               services.AddTransient<IStartupFilter, HostFilteringStartupFilter>();
 
               if (string.Equals("true", hostingContext.Configuration["ForwardedHeaders_Enabled"], StringComparison.OrdinalIgnoreCase))
               {
                   services.Configure<ForwardedHeadersOptions>(options =>
                   {
                       options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
                       // Only loopback proxies are allowed by default. Clear that restriction because forwarders are
                       // being enabled by explicit configuration.
                       options.KnownNetworks.Clear();
                       options.KnownProxies.Clear();
                   });
 
                   services.AddTransient<IStartupFilter, ForwardedHeadersStartupFilter>();
               }
 
               services.AddRouting();
           })
           .UseIIS()
           .UseIISIntegration();
       }

 public class UpdateService : IHostedService
    {
        Task updateTask = null;

        CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();

        public Task StartAsync(CancellationToken cancellationToken)
        {
            updateTask = Task.Run(() =>
            {
                while (cancellationTokenSource.Token.IsCancellationRequested==false)
                {
                    //Check new data...
                    Console.WriteLine(DateTime.Now + ": Executed");
                    Task.Delay(5000).Wait();
                }
            });

            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            cancellationTokenSource.Cancel();

            return Task.CompletedTask;
        }
    }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddSingleton<IHostedService, UpdateService>();
            services.AddControllers();
        }