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

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
    .ConfigureAppConfiguration((hostingContext, config) =>
    {
        config.AddXmlFile("appsettings.xml", optional: true, reloadOnChange: true);
});

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
WebHost.CreateDefaultBuilder(args)
    .ConfigureLogging(logging =>
    {
        logging.SetMinimumLevel(LogLevel.Warning);
});

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
WebHost.CreateDefaultBuilder(args)
    .ConfigureKestrel((context, options) =>
    {
        options.Limits.MaxRequestBodySize = 20000000;
});

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    //應(yīng)用程序默認名稱為：CoreWeb (也就是項目名稱)
　　string an = env.ApplicationName;
　　...
}
public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args).UseStartup<Startup>()
           .UseSetting(WebHostDefaults.ApplicationKey, "CoreWeb");

WebHost.CreateDefaultBuilder(args)
    .CaptureStartupErrors(true)

WebHost.CreateDefaultBuilder(args)
    .UseContentRoot("c:\\<content-root>")

WebHost.CreateDefaultBuilder(args)
    .UseSetting(WebHostDefaults.DetailedErrorsKey, "true")

WebHost.CreateDefaultBuilder(args)
    .UseEnvironment(EnvironmentName.Development)

WebHost.CreateDefaultBuilder(args)
    .UseSetting("https_port", "8080")

WebHost.CreateDefaultBuilder(args)
    .UseUrls("https://*:5000;https://localhost:5001;https://hostname:5002")

{
  "urls": "https://*:5005"
}

public static IWebHostBuilder CreateWebHostBuilder(string[] args)
{
    //IConfigurationBuilder的配置主機
    var config = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        //主機配置在hostsettings.json文件中指定
        .AddJsonFile("hostsettings.json", optional: true)
        //輸入的命令行參數(shù)可能會重寫從hostsettings.json文件加載的任何配置
        .AddCommandLine(args)
        .Build();

    return WebHost.CreateDefaultBuilder(args)
        .UseUrls("https://*:5001")
        .UseConfiguration(config)
        .Configure(app =>
        {
            //生成的配置委托函數(shù)
            app.Run(context =>
                context.Response.WriteAsync("Hello, World!"));
        });
}

dotnet run --urls "http://*:8080"

//Run
CreateWebHostBuilder(args).Build().Run();

//Start：非阻止方式，所有必須加上ReadLine
CreateWebHostBuilder(args).Build().Start();
Console.ReadLine();

//示例1：
public class CustomFileReader
{
    private readonly IHostingEnvironment _env;

    public CustomFileReader(IHostingEnvironment env)
    {
        _env = env;
    }
    public string ReadFile(string filePath)
    {
        var fileProvider = _env.WebRootFileProvider;
        // Process the file here
    }
}

//示例2：
public class Startup
{
    public Startup(IHostingEnvironment env)
    {
        HostingEnvironment = env;
    }
    public IHostingEnvironment HostingEnvironment { get; }
    public void ConfigureServices(IServiceCollection services)
    {
        if (HostingEnvironment.IsDevelopment())
        {
            // Development configuration
        }
        else
        {
            // Staging/Production configuration
        }
        var contentRootPath = HostingEnvironment.ContentRootPath;
    }
}

//示例3：
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        // In Development, use the Developer Exception Page
        app.UseDeveloperExceptionPage();
    }
    else
    {
        // In Staging/Production, route exceptions to /error
        app.UseExceptionHandler("/error");
    }
    var contentRootPath = env.ContentRootPath;
}

public async Task Invoke(HttpContext context, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        // Configure middleware for Development
    }
    else
    {
        // Configure middleware for Staging/Production
    }
    var contentRootPath = env.ContentRootPath;
}

public class Startup
{
    public void Configure(IApplicationBuilder app, IApplicationLifetime appLifetime)
    {
        appLifetime.ApplicationStarted.Register(OnStarted);
        appLifetime.ApplicationStopping.Register(OnStopping);
        appLifetime.ApplicationStopped.Register(OnStopped);
        Console.CancelKeyPress += (sender, eventArgs) =>
        {
            appLifetime.StopApplication();
            // Don't terminate the process immediately, wait for the Main thread to exit gracefully.
            eventArgs.Cancel = true;
        };
    }
    private void OnStarted()
    {
        // Perform post-startup activities here
    }
    private void OnStopping()
    {
        // Perform on-stopping activities here
    }
    private void OnStopped()
    {
        // Perform post-stopped activities here
    }
}

public class MyClass
{
    private readonly IApplicationLifetime _appLifetime;
    public MyClass(IApplicationLifetime appLifetime)
    {
        _appLifetime = appLifetime;
    }
    public void Shutdown()
    {
        _appLifetime.StopApplication();
    }
}

WebHost.CreateDefaultBuilder(args)
    .UseDefaultServiceProvider((context, options) => {
        options.ValidateScopes = true;
})