package com.example.xml.dom4j;

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

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

/**
 * dom4j框架学习 使用dom4j框架创建xml文档并输出保存
 * 
 */
public class Dom4JTest1
{

    public static void main(String[] args) throws Exception
    {
        // 第一种方式：创建文档，并创建根元素
        // 创建文档:使用了一个Helper类
        Document document = DocumentHelper.createDocument();

        // 创建根节点并添加进文档
        Element root = DocumentHelper.createElement("student");
        document.setRootElement(root);

        // 第二种方式:创建文档并设置文档的根元素节点
        Element root2 = DocumentHelper.createElement("student");
        Document document2 = DocumentHelper.createDocument(root2);

        // 添加属性
        root2.addAttribute("name", "zhangsan");
        // 添加子节点:add之后就返回这个元素
        Element helloElement = root2.addElement("hello");
        Element worldElement = root2.addElement("world");

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

        // 输出
        // 输出到控制台
        XMLWriter xmlWriter = new XMLWriter();
        xmlWriter.write(document);

        // 输出到文件
        // 格式
        OutputFormat format = new OutputFormat("    ", true);// 设置缩进为4个空格，并且另起一行为true
        XMLWriter xmlWriter2 = new XMLWriter(
                new FileOutputStream("student.xml"), format);
        xmlWriter2.write(document2);

        // 另一种输出方式，记得要调用flush()方法,否则输出的文件中显示空白
        XMLWriter xmlWriter3 = new XMLWriter(new FileWriter("student2.xml"),
                format);
        xmlWriter3.write(document2);
        xmlWriter3.flush();
        // close()方法也可以

    }
}

<?xml version="1.0" encoding="UTF-8"?>
<student/>

<?xml version="1.0" encoding="UTF-8"?>

<student name="zhangsan">
    <hello>hello Text</hello>
    <world>world text</world>
</student>

<?xml version="1.0" encoding="UTF-8"?>

<students name="zhangsan">
    <hello name="lisi">hello Text1</hello>
    <hello name="lisi2">hello Text2</hello>
    <hello name="lisi3">hello Text3</hello>
    <world name="wangwu">world text1</world>
    <world name="wangwu2">world text2</world>
    <world >world text3</world>
</students>

package com.example.xml.dom4j;

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

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

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

/**
 * dom4j框架学习： 读取并解析xml
 * 
 * 
 */
public class Dom4JTest2
{
    public static void main(String[] args) throws Exception
    {
        SAXReader saxReader = new SAXReader();

        Document document = saxReader.read(new File("students.xml"));

        // 获取根元素
        Element root = document.getRootElement();
        System.out.println("Root: " + root.getName());

        // 获取所有子元素
        List<Element> childList = root.elements();
        System.out.println("total child count: " + childList.size());

        // 获取特定名称的子元素
        List<Element> childList2 = root.elements("hello");
        System.out.println("hello child: " + childList2.size());

        // 获取名字为指定名称的第一个子元素
        Element firstWorldElement = root.element("world");
        // 输出其属性
        System.out.println("first World Attr: "
                + firstWorldElement.attribute(0).getName() + "="
                + firstWorldElement.attributeValue("name"));

        System.out.println("迭代输出-----------------------");
        // 迭代输出
        for (Iterator iter = root.elementIterator(); iter.hasNext();)
        {
            Element e = (Element) iter.next();
            System.out.println(e.attributeValue("name"));

        }

        System.out.println("用DOMReader-----------------------");
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        // 注意要用完整类名
        org.w3c.dom.Document document2 = db.parse(new File("students.xml "));

        DOMReader domReader = new DOMReader();

        // 将JAXP的Document转换为dom4j的Document
        Document document3 = domReader.read(document2);

        Element rootElement = document3.getRootElement();

        System.out.println("Root: " + rootElement.getName());

    }

}

Root: students
total child count: 6
hello child: 3
first World Attr: name=wangwu
迭代输出-----------------------
lisi
lisi2
lisi3
wangwu
wangwu2
null
用DOMReader-----------------------
Root: students