不能将类型'Microsoft.Extensions.Hosting.IHost‘隐式转换为'Microsoft.Extensions.Hosting.IHostBuilder’

Question

我有一个应用程序，它将在AWS上运行HTTP和HTTPS (尽可能重定向到HTTPS )，当我试图构建它时，我一直收到上面的错误。下面是我的代码：

using System;
using System.Net;
using System.Linq;
using System.Threading.Tasks;
using System.Collections.Generic;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Configuration;
namespace gradesApp {
    public class Program {
        public static void Main(string[] args) {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder => {
                    webBuilder
                    .UseKestrel(options => {
                                    options.Listen(IPAddress.Loopback, 5000);                    // http:localhost:5000
                                    options.Listen(IPAddress.Loopback, 5001, listenOptions => {  // https:localhost:5001
                                        listenOptions.UseHttps("certificate.pfx");
                                    });
                                    options.Listen(IPAddress.Any, 80);                           // http:*:80
                                    options.Listen(IPAddress.Any, 443, listenOptions => {        // https:*:443
                                        listenOptions.UseHttps("certificate.pfx");
                                    });
                                })
                    .UseStartup<Startup>();
                })
                .Build();
    }
}

我是不是漏掉了什么？根据请求，下面是错误本身：

/source/aspnetapp/Program.cs(18,13): error CS0266: Cannot implicitly convert type 'Microsoft.Extensions.Hosting.IHost' to 'Microsoft.Extensions.Hosting.IHostBuilder'. An explicit conversion exists (are you missing a cast?) [/source/aspnetapp/gradesApp.csproj]

Answer 1

在.CreateDefaultBuilder(args)之后删除.Build()。

与IHostBuilder类型的值的CreateHostBuilder期望值一样。

对于.Build()，它返回IHost，这是与IHostBuilder不匹配的类型。

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder => {
            webBuilder
            .UseKestrel(options => {
                ...
            })
            .UseStartup<Startup>();
        });