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, "");//插入root根节点
	SAXBuilder sax = new SAXBuilder(); 
	// 过滤不合法字符
	Document doc = (Document) sax.build(new StringReader(document.append("")
	.toString().replaceAll("[\\x00-\\x08\\x0b-\\x0c\\x0e-\\x1f]", "")));
	Element root = doc.getRootElement();