java genrate xml file use data from database

public static void main(String[] args) {
        Connection con = ConDB.Con();
        PreparedStatement pst = null;
        ResultSet rs = null;
        String colName;
        try {
            pst = con.prepareStatement("SELECT * FROM master");
            rs = pst.executeQuery();
            Document document = new Document(new Element("根元素")); //创建文档,并设根元素
            ResultSetMetaData rsmd = rs.getMetaData(); //获取字段名,返回ResultSetMetaData对像
            int numberOfColumns = rsmd.getColumnCount();
            while (rs.next()) {
                Element element0 = new Element("users"); //创建元素 生成JDOM树
                document.getRootElement().addContent(element0);
//                Element element2 = new Element("userphone");
//                element0.addContent(element2);
                for (int i = 1; i <= numberOfColumns; i++) {
                    try {
                        colName = new String(rs.getString(i));
                        //构造元素节点和文本节点
                        Element element = new Element(rsmd.getColumnName(i)).setText(colName);
                            element0.addContent(element);
                    } catch (Exception ex1) {
                    }
                }
            }
            //org.jdom.output.XMLOutputter
            XMLOutputter outp = new XMLOutputter(Format.getPrettyFormat());
            try {
                //生成XML文件路径
                outp.output(document,new FileOutputStream("aa.xml"));
            } catch (IOException ex2) {
            }
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
    }

然后再用以下代码读取XML里面的元素
public static void main(String[] args) {
        Connection con = ConDB.Con();
        PreparedStatement pst = null;
        try {
            BufferedReader br = new BufferedReader(new FileReader(
                    "aaa.xml"));
            DOMParser parser = new DOMParser();
            parser.parse(new InputSource(br));
            org.w3c.dom.Document doc = parser.getDocument();
            org.w3c.dom.NodeList nl = doc.getElementsByTagName("*");
            for (int i = 0; i < nl.getLength(); i++) {
                Node n = nl.item(i);
                System.out.println(n.getNodeName());
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }