在.net 6版本以上的web api中添加像.net 5一样的Startup.cs

Program.cs中：

       第一步：在var builder = WebApplication.CreateBuilder(args);的后面添加上：

var startup = new Startup(builder.Configuration);
startup.ConfigureServices(builder.Services);

        第二步：在var app = builder.Build();的后面添加上：

startup.Configure(app, builder.Environment);

 Startup.cs:

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    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();
    }

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

        app.UseRouting();

        app.UseAuthorization();

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