private String getJsonStringFromGZIP(HttpResponse response) {
    String jsonString = null;
    try {
      InputStream is = response.getEntity().getContent();
      BufferedInputStream bis = new BufferedInputStream(is);
      bis.mark(2);
      // 取前两个字节
      byte[] header = new byte[2];
      int result = bis.read(header);
      // reset输入流到开始位置
      bis.reset();
      // 判断是否是GZIP格式
      int headerData = getShort(header);
      // Gzip 流 的前两个字节是 0x1f8b
      if (result != -1 && headerData == 0x1f8b) {
        LogUtil.d("HttpTask", " use GZIPInputStream ");
        is = new GZIPInputStream(bis);
      } else {
        LogUtil.d("HttpTask", " not use GZIPInputStream");
        is = bis;
      }
      InputStreamReader reader = new InputStreamReader(is, "utf-8");
      char[] data = new char[100];
      int readSize;
      StringBuffer sb = new StringBuffer();
      while ((readSize = reader.read(data)) > 0) {
        sb.append(data, 0, readSize);
      }
      jsonString = sb.toString();
      bis.close();
      reader.close();
    } catch (Exception e) {
      LogUtil.e("HttpTask", e.toString(),e);
    }
 
    LogUtil.d("HttpTask", "getJsonStringFromGZIP net output : " + jsonString );
    return jsonString;
  }
 
  private int getShort(byte[] data) {
    return (int)((data[0]<<8) | data[1]&0xFF);
  }