dom4j读写xml文件

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(); } }}

 

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name
2.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();