在java中使用dom4j解析xml

虽然Java中已经有了Dom和Sax这两种标准解析方式

但其操作起来并不轻松，对于我这么一个初学者来说，其中部分代码是活生生的恶心

为此，伟大的第三方开发组开发出了Jdom和Dom4j等工具

鉴于目前的趋势，我们这里来讲讲Dom4j的基本用法，不涉及递归等复杂操作

 

Dom4j的用法很多，官网上的示例有那么点儿晦涩，这里就不写了

首先我们需要出创建一个xml文档，然后才能对其解析

xml文档：

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

<books> 

   <book id="001"> 

      <title>Harry Potter</title> 

      <author>J K. Rowling</author> 

   </book> 

   <book id="002"> 

      <title>Learning XML</title> 

      <author>Erik T. Ray</author> 

   </book> 

</books> 

 

示例一：用List列表的方式来解析xml

import java.io.File;

import java.util.List;



import org.dom4j.Attribute;

import org.dom4j.Document;

import org.dom4j.Element;

import org.dom4j.io.SAXReader;







public class Demo {



	public static void main(String[] args) throws Exception {

		SAXReader reader = new SAXReader();

		File file = new File("books.xml");

		Document document = reader.read(file);

		Element root = document.getRootElement();

		List<Element> childElements = root.elements();

		for (Element child : childElements) {

			//未知属性名情况下

			/*List<Attribute> attributeList = child.attributes();

			for (Attribute attr : attributeList) {

				System.out.println(attr.getName() + ": " + attr.getValue());

			}*/

			

			//已知属性名情况下

			System.out.println("id: " + child.attributeValue("id"));

			

			//未知子元素名情况下

			/*List<Element> elementList = child.elements();

			for (Element ele : elementList) {

				System.out.println(ele.getName() + ": " + ele.getText());

			}

			System.out.println();*/

			

			//已知子元素名的情况下

			System.out.println("title" + child.elementText("title"));

			System.out.println("author" + child.elementText("author"));

			//这行是为了格式化美观而存在

			System.out.println();

		}

	}



}

 

示例二：使用Iterator迭代器的方式来解析xml

import java.io.File;

import java.util.Iterator;



import org.dom4j.Attribute;

import org.dom4j.Document;

import org.dom4j.Element;

import org.dom4j.io.SAXReader;







public class Demo {

	public static void main(String[] args) throws Exception {

		SAXReader reader = new SAXReader();

		Document document = reader.read(new File("books.xml"));

		Element root = document.getRootElement();

		

		Iterator it = root.elementIterator();

		while (it.hasNext()) {

			Element element = (Element) it.next();

			

			//未知属性名称情况下

			/*Iterator attrIt = element.attributeIterator();

			while (attrIt.hasNext()) {

				Attribute a  = (Attribute) attrIt.next();

				System.out.println(a.getValue());

			}*/

			

			//已知属性名称情况下

			System.out.println("id: " + element.attributeValue("id"));

			

			//未知元素名情况下

			/*Iterator eleIt = element.elementIterator();

			while (eleIt.hasNext()) {

				Element e = (Element) eleIt.next();

				System.out.println(e.getName() + ": " + e.getText());

			}

			System.out.println();*/

			

			//已知元素名情况下

			System.out.println("title: " + element.elementText("title"));

			System.out.println("author: " + element.elementText("author"));

			System.out.println();

		}

	}

}

 运行结果：

示例三：创建xml文档并输出到文件

import java.io.File;

import java.io.FileOutputStream;



import org.dom4j.Document;

import org.dom4j.DocumentHelper;

import org.dom4j.Element;

import org.dom4j.io.OutputFormat;

import org.dom4j.io.XMLWriter;





public class Demo {

	public static void main(String[] args) throws Exception {

		Document doc = DocumentHelper.createDocument();

		//增加根节点

		Element books = doc.addElement("books");

		//增加子元素

		Element book1 = books.addElement("book");

		Element title1 = book1.addElement("title");

		Element author1 = book1.addElement("author");

		

		Element book2 = books.addElement("book");

		Element title2 = book2.addElement("title");

		Element author2 = book2.addElement("author");

		

		//为子节点添加属性

		book1.addAttribute("id", "001");

		//为元素添加内容

		title1.setText("Harry Potter");

		author1.setText("J K. Rowling");

		

		book2.addAttribute("id", "002");

		title2.setText("Learning XML");

		author2.setText("Erik T. Ray");

		

		//实例化输出格式对象

		OutputFormat format = OutputFormat.createPrettyPrint();

		//设置输出编码

		format.setEncoding("UTF-8");

		//创建需要写入的File对象

		File file = new File("D:" + File.separator + "books.xml");

		//生成XMLWriter对象，构造函数中的参数为需要输出的文件流和格式

		XMLWriter writer = new XMLWriter(new FileOutputStream(file), format);

		//开始写入，write方法中包含上面创建的Document对象

		writer.write(doc);

	}

}

 运行结果：