NetCore读取配置文件，简单实现。

    public class ConfigCommon
    {
        static ConfigCommon()
        {
            File = "appsettings.json";
            string str = System.IO.File.ReadAllText(Environment.CurrentDirectory + "\" + File);
            objx = JsonConvert.DeserializeObject<JObject>(str);
        }
        public static string File { get; set; }

        public static JObject objx;

        public static string Get(string Key)
        {
            string result = string.Empty;
            var obj = objx;
            return obj["ConnectionStrings"].Value<string>(Key);
        }
    }

    public class ConfigConst
    {
      public static  string connectionString = @ConfigCommon.Get("WuAnDBContext")+@"";
    }