public class ConfigurationManager
  {
    /// <summary>
    /// 配置内容
    /// </summary>
    private static NameValueCollection _configurationCollection = new NameValueCollection();

    /// <summary>
    /// 配置监听响应链堆栈
    /// </summary>
    private static Stack<KeyValuePair<string, FileSystemWatcher FileListeners = new Stack<KeyValuePair<string, FileSystemWatcher();

    /// <summary>
    /// 默认路径
    /// </summary>
    private static string _defaultPath = Directory.GetCurrentDirectory() + "\\appsettings.json";

    /// <summary>
    /// 最终配置文件路径
    /// </summary>
    private static string _configPath = null;

    /// <summary>
    /// 配置节点关键字
    /// </summary>
    private static string _configSection = "AppSettings";

    /// <summary>
    /// 配置外连接的后缀
    /// </summary>
    private static string _configUrlPostfix = "Url";

    /// <summary>
    /// 最终修改时间戳
    /// </summary>
    private static long _timeStamp = 0L;

    /// <summary>
    /// 配置外链关键词，例如：AppSettings.Url
    /// </summary>
    private static string _configUrlSection { get { return _configSection + "." + _configUrlPostfix; } }


    static ConfigurationManager()
    {
      ConfigFinder(_defaultPath);
    }

    /// <summary>
    /// 确定配置文件路径
    /// </summary>
    private static void ConfigFinder(string Path)
    {
      _configPath = Path;
      JObject config_json = new JObject();
      while (config_json != null)
      {
        config_json = null;
        FileInfo config_info = new FileInfo(_configPath);
        if (!config_info.Exists) break;

        FileListeners.Push(CreateListener(config_info));
        config_json = LoadJsonFile(_configPath);
        if (config_json[_configUrlSection] != null)
          _configPath = config_json[_configUrlSection].ToString();
        else break;
      }

      if (config_json == null || config_json[_configSection] == null) return;

      LoadConfiguration();
    }

    /// <summary>
    /// 读取配置文件内容
    /// </summary>
    private static void LoadConfiguration()
    {
      FileInfo config = new FileInfo(_configPath);
      var configColltion = new NameValueCollection();
      JObject config_object = LoadJsonFile(_configPath);
      if (config_object == null || !(config_object is JObject)) return;
      
      if (config_object[_configSection]!=null)
      {
        foreach (JProperty prop in config_object[_configSection])
        {
          configColltion[prop.Name] = prop.Value.ToString();
        }
      }
      
      _configurationCollection = configColltion;
    }

    /// <summary>
    /// 解析Json文件
    /// </summary>
    /// <param name="FilePath">文件路径</param>
    /// <returns></returns>
    private static JObject LoadJsonFile(string FilePath)
    {
      JObject config_object = null;
      try
      {
        StreamReader sr = new StreamReader(FilePath, Encoding.Default);
        config_object = JObject.Parse(sr.ReadToEnd());
        sr.Close();
      }
      catch { }
      return config_object;
    }

    /// <summary>
    /// 添加监听树节点
    /// </summary>
    /// <param name="info"></param>
    /// <returns></returns>
    private static KeyValuePair<string, FileSystemWatcher> CreateListener(FileInfo info)
    {

      FileSystemWatcher watcher = new FileSystemWatcher();
      watcher.BeginInit();
      watcher.Path = info.DirectoryName;
      watcher.Filter = info.Name;
      watcher.IncludeSubdirectories = false;
      watcher.EnableRaisingEvents = true;
      watcher.NotifyFilter = NotifyFilters.Attributes | NotifyFilters.CreationTime | NotifyFilters.DirectoryName | NotifyFilters.FileName | NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.Size;
      watcher.Changed += new FileSystemEventHandler(ConfigChangeListener);
      watcher.EndInit();

      return new KeyValuePair<string, FileSystemWatcher>(info.FullName, watcher);
     
    }

    private static void ConfigChangeListener(object sender, FileSystemEventArgs e)
    {
      long time = TimeStamp();
      lock (FileListeners)
      {
        if (time > _timeStamp)
        {
          _timeStamp = time;
          if (e.FullPath != _configPath || e.FullPath == _defaultPath)
          {
            while (FileListeners.Count > 0)
            {
              var listener = FileListeners.Pop();
              listener.Value.Dispose();
              if (listener.Key == e.FullPath) break;
            }
            ConfigFinder(e.FullPath);
          }
          else
          {
            LoadConfiguration();
          }
        }
      }
    }

    private static long TimeStamp()
    {
      return (long)((DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds * 100);
    }

    private static string c_configSection = null;
    public static string ConfigSection
    {
      get { return _configSection; }
      set { c_configSection = value; }
    }


    private static string c_configUrlPostfix = null;
    public static string ConfigUrlPostfix
    {
      get { return _configUrlPostfix; }
      set { c_configUrlPostfix = value; }
    }

    private static string c_defaultPath = null;
    public static string DefaultPath
    {
      get { return _defaultPath; }
      set { c_defaultPath = value; }
    }

    public static NameValueCollection AppSettings
    {
      get { return _configurationCollection; }
    }

    /// <summary>
    /// 手动刷新配置，修改配置后，请手动调用此方法，以便更新配置参数
    /// </summary>
    public static void RefreshConfiguration()
    {
      lock (FileListeners)
      {
        //修改配置
        if (c_configSection != null) { _configSection = c_configSection; c_configSection = null; }
        if (c_configUrlPostfix != null) { _configUrlPostfix = c_configUrlPostfix; c_configUrlPostfix = null; }
        if (c_defaultPath != null) { _defaultPath = c_defaultPath; c_defaultPath = null; }
        //释放掉全部监听响应链
        while (FileListeners.Count > 0)
          FileListeners.Pop().Value.Dispose();
        ConfigFinder(_defaultPath);
      }
    }

} 

{
 "AppSettings": {
  "Title": "Test",
  "Version": "1.2.1",
  "AccessToken": "123456@abc.com"
 }
}

{
  "AppSettings.Url": "D:\\test\\app1.json"
}