//如：appsettings.json中的数据格式
{
    "Connection":"testlocalhost",
    "Secret":{
        "JWT":"123",
        "User":"123"
    }
}
//见上面配置说明
读取单个配置属性：string  connection = AppSetting.GetSettingString("Connection");
//见上面配置说明
读取多个配置属性：string jwt = AppSetting.GetSection("Secret")["JWT"];