code: public static List<String> convertProviderToUrls(ProviderConfig providerConfig) {
          @SuppressWarnings("unchecked")
          List<ServerConfig> servers = providerConfig.getServer();
          if (servers != null && !servers.isEmpty()) {
              List<String> urls = new ArrayList<String>();
              for (ServerConfig server : servers) {
                  StringBuilder sb = new StringBuilder(200);
                  String host = server.getVirtualHost(); // 虚拟ip
                  if (host == null) {
                      host = server.getHost();
                      if (NetUtils.isLocalHost(host) || NetUtils.isAnyHost(host)) {
                          host = SystemInfo.getLocalHost();
                      }
                  }
  
                  Map<String, String> metaData = convertProviderToMap(providerConfig, server);
                  //noinspection unchecked
                  sb.append(server.getProtocol()).append("://").append(host).append(":")
                      .append(server.getPort()).append(server.getContextPath()).append("?version=1.0")
                      .append(convertMap2Pair(metaData));
                  urls.add(sb.toString());
              }
              return urls;
          }
          return null;
      }
docs: Convert provider to url.
  
  @param providerConfig the ProviderConfig
  @return the url list