asp.net core 3.1学习笔记——启动执行顺序

一、准备环境：

1.开发工具：Microsoft Visual Studio Professional 2019 版本 16.4.4；

2.SDK: dotnet-sdk-3.1.101-win-x64；

二、创建项目，选择WebAPI：

项目结构如下：

然后对里面每个对象方法添加对应名称的控制台输出语句，改造如下：

Program.cs 文件内容分别如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace NetCoreApi
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        #region 改造两组执行方法，对比启动执行顺序
        //1.第一组
        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration(builder =>
                {
                    Console.WriteLine("ConfigureAppConfiguration");
                })
                .ConfigureServices(builder =>
                {
                    Console.WriteLine("ConfigureServices");
                })
                .ConfigureLogging(builder =>
                {
                    Console.WriteLine("ConfigureLogging");
                })
                .ConfigureHostConfiguration(builder =>
                {
                    Console.WriteLine("ConfigureHostConfiguration");
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    Console.WriteLine("ConfigureWebHostDefaults");
                    webBuilder.UseStartup();
                });

        /*
         //2.第二组
    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                Console.WriteLine("ConfigureWebHostDefaults");
                webBuilder.UseStartup();
            })
            .ConfigureServices(builder => {
                Console.WriteLine("ConfigureServices");
            })
            .ConfigureLogging(builder => {
                Console.WriteLine("ConfigureLogging");
            })
            .ConfigureAppConfiguration(builder => {
                Console.WriteLine("ConfigureAppConfiguration");
            })
            .ConfigureHostConfiguration(builder => {
                Console.WriteLine("ConfigureHostConfiguration");
            });
            */ 
        #endregion
    }
}

Startup.cs 文件内容如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace NetCoreApi
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
            Console.WriteLine("Startup");
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
            Console.WriteLine("Startup.ConfigureServices");
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            Console.WriteLine("Startup.Configure");
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

对以上文件改造完毕， 两组对比（第一组和第二组）执行结果如下：

 

 启动执行顺序流程如下：

 最后附上极客时间的学习课程，.net core 的崛起，欢迎更多的小伙伴加入学习，构建更加繁荣的生态圈；