DOM4J实例，详细解说怎么用DOM4J编程

     主要类：Demo1.java,一个DOM4J实例，详细解说怎么用DOM4J编程

package com.demo;

import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.junit.Test;

public class Demo1 {
 // 获取第一个书名节点的值
 @Test
 public void read() throws DocumentException{
  SAXReader reader = new SAXReader();
  Document document = reader.read("src/book.xml");
  String value = document.getRootElement().element("book").element("bookname").getText();
  System.out.println(value);
 }
 // 获取第二个书名节点的值
 @Test
 public void read1() throws DocumentException{
  SAXReader reader = new SAXReader();
  Document document = reader.read("src/book.xml");
  Element root = document.getRootElement();
  Element book = (Element)root.elements("book").get(1);
  Element bookname = book.element("bookname");
  System.out.println(bookname.getText());
 }
 // 获取书名节点的属性值
 @Test
 public void read2() throws DocumentException{
  SAXReader reader = new SAXReader();
  Document document = reader.read("src/book.xml");
  Element root = document.getRootElement();
  String value = root.element("book").element("bookname").attributeValue("id");
  System.out.println(value); 
 }
 // 修改
 @Test
 public void update() throws Exception{
  SAXReader reader = new SAXReader();
  Document document = reader.read("src/book.xml");
  Element root = document.getRootElement();
  root.element("book").element("price").setText("60元");
  /**
   * 如果xml文件中有中文则需要转码，纯英文编码不用转
   * XMLWriter writer = new XMLWriter(new FileWriter("src/book.xml"));
    writer.write(document);
    writer.close();
        转码加入xml文件的一种方法
  XMLWriter writer = new XMLWriter(new OutputStreamWriter(new FileOutputStream("src/book.xml"),"UTF-8"));
  writer.write(document);
  writer.close();
   * */
  //转码加入xml文件的另一种方法
  OutputFormat format = OutputFormat.createPrettyPrint();
  format.setEncoding("UTF-8");
  XMLWriter writer = new XMLWriter(new FileOutputStream("src/book.xml"),format);
  writer.write(document);
  writer.close();  
 }
 // 删除
 @Test
 public void delete() throws Exception{
  SAXReader reader = new SAXReader();
  Document document = reader.read("src/book.xml");
  Element root = document.getRootElement();
  Element price = root.element("book").element("price");
  price.getParent().remove(price);
  //转码加入xml文件的一种方法
  XMLWriter writer = new XMLWriter(new OutputStreamWriter(new FileOutputStream("src/book.xml"),"UTF-8"));
  writer.write(document);
  writer.close();
 }
 //添加   给第一本书添加一个售价
 @Test
 public void insert() throws Exception{
  SAXReader reader = new SAXReader();
  Document document = reader.read("src/book.xml");
  Element root = document.getRootElement();
  //创建一个售价节点
  Element price = DocumentHelper.createElement("售价");
  price.setText("40元");
  root.element("book").add(price);
  //转码加入xml文件的另一种方法
  OutputFormat format = OutputFormat.createPrettyPrint();
  format.setEncoding("UTF-8");
  XMLWriter writer = new XMLWriter(new FileOutputStream("src/book.xml"),format);
  writer.write(document);
  writer.close(); 
 }
 //指定位置添加    给第一本书添加一个售价
 @Test
 public void insert1() throws Exception{
  SAXReader reader = new SAXReader();
  Document document = reader.read("src/book.xml");
  Element root = document.getRootElement();
  //创建一个售价节点
  Element price = DocumentHelper.createElement("售价");
  price.setText("50元");
  //指定位置添加，bookname和author中间的位置
  List list = root.element("book").elements();
  list.add(1,price);
  
  //转码加入xml文件的另一种方法
  OutputFormat format = OutputFormat.createPrettyPrint();
  format.setEncoding("UTF-8");
  XMLWriter writer = new XMLWriter(new FileOutputStream("src/book.xml"),format);
  writer.write(document);
  writer.close(); 
 }
}