code: public static Document xml(InputStream ins, Charset charset) {
          try {
              if (charset == null)
                  charset = Encoding.CHARSET_UTF8;
              return xmls().parse(new InputSource(new InputStreamReader(ins, charset)));
          }
          catch (SAXException e) {
              throw Lang.wrapThrow(e);
          }
          catch (IOException e) {
              throw Lang.wrapThrow(e);
          }
          catch (ParserConfigurationException e) {
              throw Lang.wrapThrow(e);
          }
          finally {
              Streams.safeClose(ins);
          }
      }
docs: 快捷的解析 XML 文件的帮助方法，它会主动关闭输入流
  
  @param ins
  XML 文件输入流
  @return Document 对象