public static String streamToString(InputStream is) {
  BufferedReader reader = new BufferedReader(new InputStreamReader(is));
  //new一个StringBuffer用于字符串拼接
  StringBuffer sb = new StringBuffer();
  String line = null;
  try {
    //当输入流内容读取完毕时
    while ((line = reader.readLine()) != null) {
       sb.append(line + "\n");
    }
    //记得关闭流数据 节约内存消耗
    is.close();
    reader.close();
    return sb.toString();
  } catch (IOException e) {
    e.printStackTrace();
  } 
  return null;
}