首先我们给出一段示例程序：
import java.io.File; import java.io.FileWriter; import java.util.Iterator; import org.dom4j.Document; import org.dom4j.DocumentHelper; import org.dom4j.Element; import org.dom4j.io.OutputFormat; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter; public class DOM4JTest { /** *//** */ /** *//** */ /** *//** */ /** *//** * DOM4J读写XML示例 * * @param args * @throws Exception */ public static void main(String[] args) { try { XMLWriter writer = null;// 声明写XML的对象 SAXReader reader = new SAXReader(); OutputFormat format = OutputFormat.createPrettyPrint(); format.setEncoding("GBK");// 设置XML文件的编码格式 String filePath = "d://student.xml"; File file = new File(filePath); if (file.exists()) { Document document = reader.read(file);// 读取XML文件 Element root = document.getRootElement();// 得到根节点 boolean bl = false; for (Iterator i = root.elementIterator("学生"); i.hasNext();) { Element student = (Element) i.next(); if (student.attributeValue("sid").equals("001")) { // 修改学生sid=001的学生信息 student.selectSingleNode("姓名").setText("王五"); student.selectSingleNode("年龄").setText("25"); writer = new XMLWriter(new FileWriter(filePath), format); writer.write(document); writer.close(); bl = true; break; } } if (bl) { // 添加一个学生信息 Element student = root.addElement("学生"); student.addAttribute("sid", "100"); Element sid = student.addElement("编号"); sid.setText("100"); Element name = student.addElement("姓名"); name.setText("嘎嘎"); Element sex = student.addElement("性别"); sex.setText("男"); Element age = student.addElement("年龄"); age.setText("21"); writer = new XMLWriter(new FileWriter(filePath), format); writer.write(document); writer.close(); } } else { // 新建student.xml文件并新增内容 Document _document = DocumentHelper.createDocument(); Element _root = _document.addElement("学生信息"); Element _student = _root.addElement("学生"); _student.addAttribute("sid", "001"); Element _id = _student.addElement("编号"); _id.setText("001"); Element _name = _student.addElement("姓名"); _name.setText("灰机"); Element _age = _student.addElement("年龄"); _age.setText("18"); writer = new XMLWriter(new FileWriter(file), format); writer.write(_document); writer.close(); } System.out.println("操作结束! "); } catch (Exception e) { e.printStackTrace(); } }}执行结果应该是这样：循环解析节点：
private void getAllNodes(String xml) { try { Document authtmp = DocumentHelper.parseText(xml); List<Element> list = authtmp.selectNodes("//sms/node"); for (int j = 0; j < list.size(); j++) { Element node = (Element) list.get(j); nodeByNodes(node); } } catch (Exception e) { e.printStackTrace(); } } private void nodeByNodes(Element node) { if (node.element("node") != null) { String id = node.attributeValue("id"); String name = node.attributeValue("name"); System.out.print(id + "-------"); System.out.println(name); for (Iterator i = node.elementIterator("node"); i.hasNext();) { Element newNode = (Element) i.next(); nodeByNodes(newNode); } } else { String id = node.attributeValue("id"); String name = node.attributeValue("name"); System.out.print(id + "-------"); System.out.println(name); } }其次DOM4J的解释一.Document对象相关1.读取XML文件,获得document对象.
SAXReader reader = new SAXReader(); Document document = reader.read( new File( " input.xml " ));2.解析XML形式的文本,得到document对象.
String text = " <members></members> "; Document document = DocumentHelper.parseText(text);3.主动创建document对象.
Document document = DocumentHelper.createDocument(); Element root = document.addElement( " members " ); // 创建根节点二.节点相关1.获取文档的根节点.
Element rootElm = document.getRootElement();2.取得某节点的单个子节点.
Element memberElm = root.element( " member " ); // "member"是节点名3.取得节点的文字
String text = memberElm.getText();也可以用:
String text = root.elementText( " name " );这个是取得根节点下的name字节点的文字.4.取得某节点下名为"member"的所有字节点并进行遍历.
List nodes = rootElm.elements( " member "); for (Iterator it = nodes.iterator(); it.hasNext();) { Element elm = (Element) it.next(); // do something}5.对某节点下的所有子节点进行遍历.
for (Iterator it = root.elementIterator();it.hasNext();) { Element element = (Element) it.next(); // do something }6.在某节点下添加子节点.
Element ageElm = newMemberElm.addElement( " age " );7.设置节点文字.
ageElm.setText( " 29 " );8.删除某节点.
parentElm.remove(childElm); // childElm是待删除的节点,parentElm是其父节点9.添加一个CDATA节点.
Element contentElm = infoElm.addElement( " content " ); contentElm.addCDATA(diary.getContent()); contentElm.getText(); // 特别说明：获取节点的CDATA值与获取节点的值是一个方法 contentElm.clearContent(); //清除节点中的内容，CDATA亦可三.属性相关.1.取得某节点下的某属性
Element root = document.getRootElement(); Attribute attribute = root.attribute( " size " ); // 属性名name2.取得属性的文字
String text = attribute.getText();也可以用:
String text2 = root.element( " name " ).attributeValue( " firstname " );这个是取得根节点下name字节点的属性firstname的值.3.遍历某节点的所有属性
Element root = document.getRootElement(); for (Iterator it = root.attributeIterator();it.hasNext();) { Attribute attribute = (Attribute) it.next(); String text=attribute.getText(); System.out.println(text); }4.设置某节点的属性和文字.
newMemberElm.addAttribute( " name " , " sitinspring " );5.设置属性的文字
Attribute attribute = root.attribute( " name " ); attribute.setText( " sitinspring " );6.删除某属性
Attribute attribute = root.attribute( " size " ); // 属性名name root.remove(attribute);四.将文档写入XML文件.1.文档中全为英文,不设置编码,直接写入的形式.
XMLWriter writer = new XMLWriter( new FileWriter( " output.xml " ));writer.write(document);writer.close();2.文档中含有中文,设置编码格式写入的形式.
OutputFormat format = OutputFormat.createPrettyPrint(); format.setEncoding( " GBK " ); // 指定XML编码 XMLWriter writer = new XMLWriter( new FileWriter( " output.xml " ),format); writer.write(document); writer.close();五.字符串与XML的转换1.将字符串转化为XML
String text = " <members> <member>sitinspring</member> </members> " ;Document document = DocumentHelper.parseText(text);2.将文档或节点的XML转化为字符串.
SAXReader reader = new SAXReader(); Document document = reader.read( new File( " input.xml " )); Element root = document.getRootElement(); String docXmlText = document.asXML(); String rootXmlText = root.asXML(); Element memberElm = root.element( " member " ); String memberXmlText = memberElm.asXML();