转化XML

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.SAXReader;

public class Foo {

    public Document parse(URL url) throws DocumentException {
        SAXReader reader = new SAXReader();
        Document document = reader.read(url);
        return document;
    }
}

使用迭代器

document可以通过几个返回Java标准迭代器的方法实现遍历：

public void bar(Document document) throws DocumentException {

    Element root = document.getRootElement();

    // iterate through child elements of root
    for ( Iterator i = root.elementIterator(); i.hasNext(); ) {
        Element element = (Element) i.next();
        // do something
    }

    // iterate through child elements of root with element name "foo"
    for ( Iterator i = root.elementIterator( "foo" ); i.hasNext(); ) {
        Element foo = (Element) i.next();
        // do something
    }

    // iterate through attributes of root 
    for ( Iterator i = root.attributeIterator(); i.hasNext(); ) {
        Attribute attribute = (Attribute) i.next();
        // do something
    }
 }

快速循环

快速遍历大文件：

public void treeWalk(Document document) {
     treeWalk( document.getRootElement() );
 }

 public void treeWalk(Element element) {
     for ( int i = 0, size = element.nodeCount(); i < size; i++ ) {
         Node node = element.node(i);
         if ( node instanceof Element ) {
             treeWalk( (Element) node );
         }
         else {
             // do something....
         }
     }
 }

创建XML文档

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;

public class Foo {

    public Document createDocument() {
        Document document = DocumentHelper.createDocument();
        Element root = document.addElement( "root" );

        Element author1 = root.addElement( "author" )
            .addAttribute( "name", "James" )
            .addAttribute( "location", "UK" )
            .addText( "James Strachan" );

        Element author2 = root.addElement( "author" )
            .addAttribute( "name", "Bob" )
            .addAttribute( "location", "US" )
            .addText( "Bob McWhirter" );

        return document;
    }
}

将文档写入文件

一种快速而且简单的方式如下：

FileWriter out = new FileWriter( "foo.xml" );
document.write( out );

如果想要修改输出的格式，如智能缩进输出或者紧凑输出，或者你想要使用writer对象或者OutputStream对象来完成其他任务，则可以使用XMLWriter类。

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 );
    }
}

与String的转化

如果有到Document或者其他结点如Attribute、Element等的引用，则可以用asXML()方法将其转化为默认的XML文本。

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

如果有String形式的XML，则可以使用DocumentHelper.parseText()将其转化为Document。

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

其他操作

1 取得某结点下的某个子节点或属性

Element root = document.getRootElement();
Element elem = root.element("book");
Attribute attribute = root.attribute("id");

2 取得属性的内容

String text = attribute.getText();

3 删除某属性