首先我们给出一段示例程序：
1.读取XML文件,获得document对象.
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
{
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
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();