XML解析 dom4j的施用

XML解析 dom4j的使用
Parsing XML

For example if you wish to find all the hypertext links in an XHTML document the following code would do the trick.

    public void findLinks(Document document) throws DocumentException {        List list = document.selectNodes( "//a/@href" );        for (Iterator iter = list.iterator(); iter.hasNext(); ) {            Attribute attribute = (Attribute) iter.next();            String url = attribute.getValue();        }    }

If you need any help learning the XPath language we highly recommend the Zvon tutorial which allows you to learn by example.

If you want to be able to change the format of the output, such as pretty printing or a compact format, or you want to be able to work with Writer objects or OutputStream objects as the destination, then you can use the XMLWriter class.

import org.dom4j.Document;import org.dom4j.io.OutputFormat;import org.dom4j.io.XMLWriter;public class Foo {    public void write(Document document) throws IOException {        // lets write to a file        XMLWriter writer = new XMLWriter(            new FileWriter( "output.xml" )        );        writer.write( document );        writer.close();        // Pretty print the document to System.out        OutputFormat format = OutputFormat.createPrettyPrint();        writer = new XMLWriter( System.out, format );        writer.write( document );        // Compact format to System.out        format = OutputFormat.createCompactFormat();        writer = new XMLWriter( System.out, format );        writer.write( document );    }}

If you have a reference to a Document or any other Node such as an Attribute or Element, you can turn it into the default XML text via the asXML() method.

        Document document = ...;        String text = document.asXML();

If you have some XML as a String you can parse it back into a Document again using the helper method DocumentHelper.parseText()

        String text = "<person> <name>James</name> </person>";        Document document = DocumentHelper.parseText(text);

Applying XSLT on a Document is quite straightforward using the JAXP API from Sun. This allows you to work against any XSLT engine such as Xalan or SAXON. Here is an example of using JAXP to create a transformer and then applying it to a Document.

import javax.xml.transform.Transformer;import javax.xml.transform.TransformerFactory;import org.dom4j.Document;import org.dom4j.io.DocumentResult;import org.dom4j.io.DocumentSource;public class Foo {    public Document styleDocument(        Document document,         String stylesheet    ) throws Exception {        // load the transformer using JAXP        TransformerFactory factory = TransformerFactory.newInstance();        Transformer transformer = factory.newTransformer(             new StreamSource( stylesheet )         );        // now lets style the given document        DocumentSource source = new DocumentSource( document );        DocumentResult result = new DocumentResult();        transformer.transform( source, result );        // return the transformed document        Document transformedDoc = result.getDocument();        return transformedDoc;    }}