.net core /.net5 如何读取appsettings.json中的DefaultConnection值？

直接上代码：

配置文件

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "DefaultConnection": "server=1.1.1.1;port=111;database=test1;SslMode=None;uid=root;pwd=123456;Allow User Variables=true"
  }
}

项目启动代码：
Startup.cs文件中（精简了一部分无关内容）

using Autofac;

using Exceptionless;

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

using System.Reflection;

using XJ.dDatabase.ConnectionPool;
using XJ.dDatabase.Repository;
using XJ.dDatabase.Service;

namespace XJ.wWeb
{
    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)
        {
            #region 读取
            var defaultConnection = Configuration.GetConnectionString("DefaultConnection");
            if (!string.IsNullOrEmpty(defaultConnection))
            {
                ConnectionPoolHelper._mySqlConnection = defaultConnection;
            }
            else
            {
                return;
            }
            #endregion

            services
                //.Configure<>() 读取配置暂时就不写了，反正当前能够顺利读取到DefaultConnection得值
                .AddControllersWithViews()
                .AddRazorRuntimeCompilation();
        }


     
    }
}