Java使用SAX解析无根节点的xml文件并过滤不合法字符

使用HttpURLConnection请求远程读取xml文件，针对无根节点的xml文件，在首位添加根节点，并进行过滤，代码如下

        URL url = new URL(path); 
		//URL url = new URL("http://192.168.11.111:8080/xxxx/"+path);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
		conn.connect(); 
		InputStream stream = conn.getInputStream(); 
		BufferedReader reader = new BufferedReader(new InputStreamReader(stream, "UTF-8")); 
		StringBuffer document = new StringBuffer(); 
		String line = null; 
		while ((line = reader.readLine()) != null) { 
			document.append(line); 
		}
		document.insert(document.indexOf(">")+1, "<root>");//插入root根节点
		SAXBuilder sax = new SAXBuilder(); 
		Document doc = (Document) sax.build(new StringReader(document.append("</root>").toString().replaceAll("[\\x00-\\x08\\x0b-\\x0c\\x0e-\\x1f]", ""))); //过滤不合法字符
		Element root = doc.getRootElement();