用dom4j对xml进行创建、加载和更新
自：http://hi.baidu.com/waltertan/blog/item/3e705cc7085187d7d0006053.html
import java.io.File;import java.io.FileWriter;import java.io.IOException;import java.util.Iterator;import java.util.List;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.DocumentHelper;import org.dom4j.Element;import org.dom4j.io.SAXReader;import org.dom4j.io.XMLWriter;public class Dom4j_Test {/*** @param args*///加载现有的xml文件到内存中public void load(String paht){ Document doc = null; Element root = null; List<Element> list = null; SAXReader reader = new SAXReader(); try { doc = reader.read(new File(paht)); } catch (DocumentException e) { // TODO Auto-generated catch block e.printStackTrace(); } if(doc != null){ root = doc.getRootElement(); list = root.element("students").elements("student"); for(Iterator<Element> it=list.iterator();it.hasNext();){ Element element = it.next(); System.out.print(element.attributeValue("id")+" "+element.elementText("name")+" "); System.out.println(element.elementText("gender")); } }}//创建一个xml的数据岛，并写进数据public void create(String path){ Document document = DocumentHelper.createDocument(); Element root = document.addElement("root"); Element elm = root.addElement("book"); elm.addText("Java"); root.addElement("book").addAttribute("id", "2").addText("C#"); try { XMLWriter writer = new XMLWriter(new FileWriter(path)); writer.write(document); writer.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }}//更新现有的xml文件（以追加元素为例）public void update(String path){ SAXReader reader = new SAXReader(); Document doc = null; try { doc = reader.read(new File(path));//将现有的xml文件读进内存 } catch (DocumentException e) { // TODO Auto-generated catch block e.printStackTrace(); } //开始修改xml文件（在内存中修改） if(doc != null){ Element elm = doc.getRootElement().element("students"); Element elm2 = elm.addElement("student").addAttribute("id", "3"); elm2.addElement("name").addText("Jennet"); elm2.addElement("gender").addText("female"); //将修改后的xml文件写到磁盘上 try { XMLWriter writer = new XMLWriter(new FileWriter(path)); writer.write(doc); writer.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } }}public static void main(String[] args) { // TODO Auto-generated method stub Dom4j_Test test = new Dom4j_Test(); test.create("my2.xml"); test.load("my1.xml"); test.update("my1.xml");}}