（九）XML之DOM4J詳解

DOM4J是JDOM項目的部分人員開發的另一個XML解析框架，與JDOM差不多。

 

創建XML文檔並在命令行輸出，同時輸出爲文件：

import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

public class Test1
{
    public static void main(String[] args) throws Exception
    {
        //創建文檔並設置文檔的根元素節點：第一種方式
//      Document document = DocumentHelper.createDocument();
//
//      Element root = DocumentHelper.createElement("student");
//
//      document.setRootElement(root);

        //創建文檔並設置文檔的根元素節點：第二種方式
        Element root = DocumentHelper.createElement("student");
        Document document = DocumentHelper.createDocument(root);

        root.addAttribute("name", "zhangsan");
        Element helloElement = root.addElement("hello");
        Element worldElement = root.addElement("world");

        helloElement.setText("hello");
        worldElement.setText("world");

        helloElement.addAttribute("test", "haha");

        XMLWriter xmlWriter = new XMLWriter();
        xmlWriter.write(document);

        OutputFormat format = new OutputFormat("    ",true);
        XMLWriter xmlWriter2 = new XMLWriter(new FileOutputStream("student2.xml"),format);
        xmlWriter2.write(document);

        XMLWriter xmlWriter3 = new XMLWriter(new FileWriter("student3.xml"),format);
        xmlWriter3.write(document);
        xmlWriter3.flush();
        //
    }
}

對一個已有xml進行解析

import java.io.File;
import java.util.Iterator;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

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

public class Test2
{
    public static void main(String[] args) throws Exception
    {
        SAXReader saxReader = new SAXReader();
        Document doc = saxReader.read(new File("student2.xml"));

        Element root = doc.getRootElement();
        System.out.println("root element:" + root.getName());

        List childList = root.elements();
        System.out.println(childList.size());

        List childList2 = root.elements("hello");
        System.out.println(childList2.size());

        Element first = root.element("hello");
        System.out.println(first.attributeValue("test"));

        for(Iterator iter = root.elementIterator();iter.hasNext();)
        {
            Element e = (Element)iter.next();
            System.out.println(e.attributeValue("test"));
        }
        System.out.println("---------------------");

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        org.w3c.dom.Document document = db.parse(new File("student2.xml"));

        DOMReader domReader = new DOMReader();

        //將JAXP的Document轉換爲dom4j的Document
        Document d = domReader.read(document);

        Element rootElement = d.getRootElement();
        System.out.println(rootElement.getName());


        }
    }

DOMReader的read方法可以將JAXP的Document轉換爲dom4j的Document，然後使用dom4j的方法來進行解析。

如果你的myeclipse的工作空間文本文件的編碼方式爲默認（默認爲GBK），使用JDOM或dom4j的輸出方法默認輸出的xml文件編碼是utf-8，如果xml中有漢字，則將出現亂碼現象，好的作法是將工作空間的編碼格式改爲utf-8。