java dom4j创建 ，修改 ，删除 xml文件内容

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.dom4j.Attribute;
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 writer3 {
    @Test
/**
创建xml  节点信息
*/
    public void modify1(){
        Document doc=DocumentHelper.createDocument();
        
        Element rootelem=doc.addElement("contactList");
        Element contactelem= rootelem.addElement("contact");
        contactelem.addAttribute("id","001").addAttribute("name","eric");  //直接在节点上写入属性值
        contactelem.addElement("name").addText("张三");    //增加标签 name   内容是文本
        contactelem.addElement("age").addText("20");      //增加标签  age    内容属于文本
        
        //无论 是创建 ，修改，还是删除后都要 写出到文件中   
      FileOutputStream  out=new  FileOutputStream("e:/contact2.xml");
      OutputFormat format = OutputFormat.createPrettyPrint();
      format.setEncoding("utf-8");
      XMLWriter writer= new XMLWriter(out,format);
      writer.write(doc);
      writer.close();

创建效果如下：

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

<contactList> 
  <contact > 
    <name>jimi</name>  
    <age>20</age> 
  </contact> 
</contactList>

修改代码段：

    @Test
    public void modify3() throws Exception   {
        
       //修改就这三行代码
        Document doc= new SAXReader().read(new File("e:/contact2.xml"));
        Element name=doc.getRootElement().element("contact").element("name");
        name.setText("jimi");

        FileOutputStream out = new FileOutputStream("e:/contact2.xml");
        OutputFormat format = OutputFormat.createPrettyPrint();
        format.setEncoding("utf-8");
        XMLWriter writer = new XMLWriter(out,format);
        writer.write(doc);
        writer.close();

}