/// <summary>
 /// ConsulConfigurationSource
 /// </summary>
public interface IConsulConfigurationSource : IConfigurationSource
 {
  /// <summary>
  /// CancellationToken
  /// </summary>
  CancellationToken CancellationToken { get; }
 
  /// <summary>
  /// Consul構(gòu)造函數(shù)實例，可自定義傳入
  /// </summary>
  Action<ConsulClientConfiguration> ConsulClientConfiguration { get; set; }
 
  /// <summary>
  /// Consul構(gòu)造函數(shù)實例，可自定義傳入
  /// </summary>
  Action<HttpClient> ConsulHttpClient { get; set; }
 
  /// <summary>
  /// Consul構(gòu)造函數(shù)實例，可自定義傳入
  /// </summary>
  Action<HttpClientHandler> ConsulHttpClientHandler { get; set; }
 
  /// <summary>
  /// 服務(wù)名稱
  /// </summary>
  string ServiceKey { get; }
 
  /// <summary>
  /// 可選項
  /// </summary>
  bool Optional { get; set; }
 
  /// <summary>
  /// Consul查詢選項
  /// </summary>
  QueryOptions QueryOptions { get; set; }
 
  /// <summary>
  /// 重新加載延遲時間，單位是毫秒
  /// </summary>
  int ReloadDelay { get; set; }
 
  /// <summary>
  /// 是否在配置改變的時候重新加載
  /// </summary>
  bool ReloadOnChange { get; set; }
 }

 public ConsulConfigurationSource(string serviceKey, CancellationToken cancellationToken)
 {
 if (string.IsNullOrWhiteSpace(serviceKey))
 {
  throw new ArgumentNullException(nameof(serviceKey));
 }
 
 this.ServiceKey = serviceKey;
 this.CancellationToken = cancellationToken;
}

 public IConfigurationProvider Build(IConfigurationBuilder builder)
 {
  ConsulConfigurationParser consulParser = new ConsulConfigurationParser(this);
 
  return new ConsulConfigurationProvider(this, consulParser);
 }

 /// <summary>
 /// 獲取并轉(zhuǎn)換Consul配置信息
 /// </summary>
 /// <param name="reloading"></param>
 /// <param name="source"></param>
 /// <returns></returns>
 public async Task<IDictionary<string, string>> GetConfig(bool reloading, IConsulConfigurationSource source)
 {
  try
  {
   QueryResult<KVPair> kvPair = await this.GetKvPairs(source.ServiceKey, source.QueryOptions, source.CancellationToken).ConfigureAwait(false);
   if ((kvPair?.Response == null) && !source.Optional)
   {
    if (!reloading)
    {
     throw new FormatException(Resources.Error_InvalidService(source.ServiceKey));
    }
 
    return new Dictionary<string, string>();
   }
 
   if (kvPair?.Response == null)
   {
    throw new FormatException(Resources.Error_ValueNotExist(source.ServiceKey));
   }
 
   this.UpdateLastIndex(kvPair);
 
   return JsonConfigurationFileParser.Parse(source.ServiceKey, new MemoryStream(kvPair.Response.Value));
  }
  catch (Exception exception)
  {
   throw exception;
  }
 }
 
 /// <summary>
 /// Consul配置信息監(jiān)控
 /// </summary>
 /// <param name="key"></param>
 /// <param name="cancellationToken"></param>
 /// <returns></returns>
 public IChangeToken Watch(string key, CancellationToken cancellationToken)
 {
  Task.Run(() => this.RefreshForChanges(key, cancellationToken), cancellationToken);
 
  return this.reloadToken;
 }

public sealed class ConsulConfigurationProvider : ConfigurationProvider
 {
  private readonly ConsulConfigurationParser configurationParser;
  private readonly IConsulConfigurationSource source;
 
  public ConsulConfigurationProvider(IConsulConfigurationSource source, ConsulConfigurationParser configurationParser)
  {
   this.configurationParser = configurationParser;
   this.source = source;
 
   if (source.ReloadOnChange)
   {
    ChangeToken.OnChange(
     () => this.configurationParser.Watch(this.source.ServiceKey, this.source.CancellationToken),
     async () =>
     {
      await this.configurationParser.GetConfig(true, source).ConfigureAwait(false);
 
      Thread.Sleep(source.ReloadDelay);
 
      this.OnReload();
     });
   }
  }
 
  public override void Load()
  {
   try
   {
    this.Data = this.configurationParser.GetConfig(false, this.source).ConfigureAwait(false).GetAwaiter().GetResult();
   }
   catch (AggregateException aggregateException)
   {
    throw aggregateException.InnerException;
   }
  }
 }

 public class Program
 {
  public static void Main(string[] args)
  {
   CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
 
   WebHost.CreateDefaultBuilder(args).ConfigureAppConfiguration(
    (hostingContext, builder) =>
    {
     builder.AddConsul("userservice", cancellationTokenSource.Token, source =>
     {
      source.ConsulClientConfiguration = cco => cco.Address = new Uri("http://localhost:8500");
      source.Optional = true;
      source.ReloadOnChange = true;
      source.ReloadDelay = 300;
      source.QueryOptions = new QueryOptions
      {
       WaitIndex = 0
      };
     });
 
     builder.AddConsul("commonservice", cancellationTokenSource.Token, source =>
     {
      source.ConsulClientConfiguration = cco => cco.Address = new Uri("http://localhost:8500");
      source.Optional = true;
      source.ReloadOnChange = true;
      source.ReloadDelay = 300;
      source.QueryOptions = new QueryOptions
      {
       WaitIndex = 0
      };
     });
    }).UseStartup<Startup>().Build().Run();
  }
 }