dom读取xml文件的问题

我有一个xml文件：



deltaQuery="select Uid from User where lastmodify > '${dataimporter.last_index_time}'">











该xml文件没有<?xml...>等标签

我想读取出dataSource标签中driver url等值，写了一个类如下：
File file = new File("data_config.xml");

    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

    DocumentBuilder builder=dbf.newDocumentBuilder();

    Document doc=builder.parse(file);

    NodeList dataSource = doc.getElementsByTagName("dataSource");

    System.out.println(dataSource.getLength());
    for(int i=0;i<dataSource.getLength();i++)
    {
        Node node=dataSource.item(i);
        System.out.println(node);
        System.out.println(node.getNodeValue());
    }

总是说读到的null。
求大牛指正。

另外：我想读取所有filed下的column 和name标签的值，该怎么写呢？

File file = new File("data_config.xml");

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

DocumentBuilder builder=dbf.newDocumentBuilder();

Document doc=builder.parse(file);

[color=red]//获取文档的根元素，赋值给rootElement变量

Element rootElement = document.getDocumentElement();

NodeList dataSource = rootElement.getElementsByTagName("dataSource"); [/color]

System.out.println(dataSource.getLength());
for(int i=0;i<dataSource.getLength();i++)
{
Node node=dataSource.item(i);
System.out.println(node);
System.out.println(node.getNodeValue());
}

[code="java"]public class Test {

/**
 * @param args
 * @throws ParserConfigurationException 
 * @throws IOException 
 * @throws SAXException 
 */
public static void main(String[] args) throws ParserConfigurationException,
        SAXException, IOException {
    // TODO Auto-generated method stub
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

    DocumentBuilder builder = dbf.newDocumentBuilder();

    File file = new File("c:\\c.xml");

    Document doc = builder.parse(file);

    NodeList dataSource = doc.getElementsByTagName("dataSource");
    for (int i = 0; i < dataSource.getLength(); i++) {
        Node node = dataSource.item(i);
        Element element = (Element) node;
        System.out.println(element.getAttribute("url"));
    }
    NodeList field = doc.getElementsByTagName("field");

    for (int i = 0; i < field.getLength(); i++) {
        Node node = field.item(i);
        Element element = (Element) node;
        System.out.println(element.getAttribute("column"));
        System.out.println(element.getAttribute("name"));
    }

}

}[/code]

应该像1楼那样获得root节点，然后访问数据，还有提醒楼主注意文件路径应该写正确