public static IConfigurationRoot LoadSettings(this IHostEnvironment env)
        {
            return new ConfigurationBuilder()
                 .SetBasePath(AppDomain.CurrentDomain.BaseDirectory)
                 .AddJsonFile("common.json", optional: true, reloadOnChange: false)
                 .AddJsonFile("appsettings.json", optional: true, reloadOnChange: false)
                 .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: false)
                 .AddEnvironmentVariables()
                 .Build();
        }

        private readonly IConfiguration _configuration;
        public Startup(IWebHostEnvironment env)
        {
            _configuration = env.LoadSettings();
        }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration((hostingContext, config) =>
            {
                var env = hostingContext.HostingEnvironment;
                config.SetBasePath(env.ContentRootPath);
                config.AddJsonFile("devappsettings.json", optional: false, reloadOnChange: true);
            })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });

            var builder = new ConfigurationBuilder();
            var profileCollection = new Dictionary<string, string>
            {
                {"AuthorProfile:FirstName", "Joydip"},
                {"AuthorProfile:LastName", "Kanjilal"},
                {"AuthorProfile:Address", "Hyderabad, India"}
            };
            builder.AddInMemoryCollection(profileCollection);
            Configuration = builder.Build();

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration((hostingContext, config) =>
            {
                var builder = new ConfigurationBuilder();
                var profileCollection = new Dictionary<string, string>
            {
                {"AuthorProfile:FirstName", "Joydip"},
                {"AuthorProfile:LastName", "Kanjilal"},
                {"AuthorProfile:Address", "Hyderabad, India"}
            };
                builder.AddInMemoryCollection(profileCollection);
                config.AddConfiguration(builder.Build());
            })
            .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });

    public class AppSettings
    {
        private static IConfiguration Configuration { get; set; }

        public AppSettings(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        /// <summary>
        /// 封裝要操作的字符
        /// </summary>
        /// <param name="sections"></param>
        /// <returns></returns>
        public static string GetValue(params string[] sections)
        {
            try
            {
                if (sections.Any())
                    return Configuration[string.Join(":", sections)];
            }
            catch (Exception)
            { }
            return "";
        }

        /// <summary>
        /// 遞歸獲取配置信息數(shù)組
        ///引用 Microsoft.Extensions.Configuration.Binder 包
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="sections"></param>
        /// <returns></returns>
        public static List<T> App<T>(params string[] sections)
        {
            List<T> list = new List<T>();
            Configuration.Bind(string.Join(":", sections), list);
            return list;
        }
    }

services.AddSingleton(new AppSettings(Configuration));

var info = AppSettings.GetValue("Logging", "LogLevel");