使用dom4j 生成XML

由于前段时间，程序中用到一点点ajax,后台的servlet要向前台的页面产生xml数据，当时就简单得使用了 StringBuffer,自己简单的组装了一下，有一点比较麻烦的是，转义字符的问题，例如，
     

  String name = "This is test<p> ";
		StringBuffer buffer = new StringBuffer();
		buffer.append("<name>"+name.replace("&", "&amp;")+"</name>");
		buffer.append("<name>"+name.replace("<", "&lt;")+"</name>");
      

所以我就想研究一下dom4j的生成xml文件的方式，下面的例子是我将developerworks上面抄下来的。

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

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


public class XmlDom4J {
	public void generateDocument(){
		Document document = DocumentHelper.createDocument();
		Element catalogElement = document.addElement("catalog");
		catalogElement.addComment("An &&&XML Catalog");
		
		catalogElement.addProcessingInstruction("target", "text");
		
		Element journalElement = catalogElement.addElement("journal");
		journalElement.addAttribute("title", "&&&XML Zone&&&");
		journalElement.addAttribute("publisher","IBM developerWorks");
		
		Element articleElement = journalElement.addElement("article");
		articleElement.addAttribute("level", "Intermediate");
		articleElement.addAttribute("date", "December-2001");
		
		Element titleElement = articleElement.addElement("title");
		titleElement.setText("Java configuration with XML Schema");
		
		Element authorElement = articleElement.addElement("author");
		Element firstNameElement = authorElement.addElement("firstName");
		firstNameElement.setText("Marcello");
		Element lastNameElement = authorElement.addElement("lastName");
		lastNameElement.setText("Vitaletti");
		
		try {
			XMLWriter xmlWriter = new XMLWriter( 
					new FileWriter(
							new File("C:/catalog/catalog.xml")));
			xmlWriter.write(document);
			xmlWriter.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		XmlDom4J xmlDom = new XmlDom4J();
		xmlDom.generateDocument();
	}
}

第17行代码我不懂是什么意思，请各位达人指导。
生成的xml文件如下：

<?xml version="1.0" encoding="UTF-8" ?> 
- <catalog>
- <!-- An &&&XML Catalog
  --> 
  <?target text?> 
- <journal title="&&&XML Zone&&&" publisher="IBM developerWorks">
- <article level="Intermediate" date="December-2001">
  <title>Java configuration with XML Schema</title> 
- <author>
  <firstName>Marcello</firstName> 
  <lastName>Vitaletti</lastName> 
  </author>
  </article>
  </journal>
  </catalog>