private String getNotModified(String dataId, CacheData cacheData, HttpMethod httpMethod) {
    Header md5Header = httpMethod.getResponseHeader(Constants.CONTENT_MD5);
    if (null == md5Header) {
      throw new RuntimeException("RP_NO_CHANGE response not contain MD5");
    }
    String md5 = md5Header.getValue();
    if (!cacheData.getMd5().equals(md5)) {
      String lastMd5 = cacheData.getMd5();
      cacheData.setMd5(Constants.NULL);
      cacheData.setLastModifiedHeader(Constants.NULL);

      throw new RuntimeException(
          "MD5 verify error,DataID:["
              + dataId
              + "]MD5 last:["
              + lastMd5
              + "]MD5 current:["
              + md5
              + "]");
    }

    cacheData.setMd5(md5);
    changeSpacingInterval(httpMethod);
    if (log.isInfoEnabled()) {
      log.info("DataId: " + dataId + ",not changed");
    }
    return null;
  }
  private String getSuccess(
      String dataId, String group, CacheData cacheData, HttpMethod httpMethod) {
    String configInfo = Constants.NULL;
    configInfo = getContent(httpMethod);
    if (null == configInfo) {
      throw new RuntimeException("RP_OK configInfo is null");
    }

    Header md5Header = httpMethod.getResponseHeader(Constants.CONTENT_MD5);
    if (null == md5Header) {
      throw new RuntimeException("RP_OK not contain MD5, " + configInfo);
    }
    String md5 = md5Header.getValue();
    if (!checkContent(configInfo, md5)) {
      throw new RuntimeException(
          "MD5 verify error,DataID:["
              + dataId
              + "]ConfigInfo:["
              + configInfo
              + "]MD5:["
              + md5
              + "]");
    }

    Header lastModifiedHeader = httpMethod.getResponseHeader(Constants.LAST_MODIFIED);
    if (null == lastModifiedHeader) {
      throw new RuntimeException("RP_OK result not contain lastModifiedHeader");
    }
    String lastModified = lastModifiedHeader.getValue();

    cacheData.setMd5(md5);
    cacheData.setLastModifiedHeader(lastModified);

    changeSpacingInterval(httpMethod);

    String key = makeCacheKey(dataId, group);
    contentCache.put(key, configInfo);

    StringBuilder buf = new StringBuilder();
    buf.append("dataId=").append(dataId);
    buf.append(" ,group=").append(group);
    buf.append(" ,content=").append(configInfo);
    dataLog.info(buf.toString());

    return configInfo;
  }