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使用dom进行xml解析：

dom解析相关类是jdk自带的类，使用dom解析时无需引入其他jar包，直接使用即可：

以下是一个dom解析xml的实例，xml内容如下：

<?xml version="1.0" encoding="GBK"?>
<addresslist>
	<linkman>
		<name>张三</name>
		<email>www@qq.com</email>
	</linkman>
	<linkman>
		<name>李四</name>
		<email>lisi@sina.com</email>
	</linkman>
</addresslist>

java解析程序如下：

package com.fcy.xml.dom;

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

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class DOMRead {
	public static void main(String[] args) throws Exception{
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = null;
		builder = factory.newDocumentBuilder();
		Document doc = null;
		doc = builder.parse("d://test//dom_demo.xml");
		NodeList nl = doc.getElementsByTagName("linkman");
		int length = nl.getLength();
		for(int x = 0; x < length; x++){
			Element e = (Element) nl.item(x);
			System.out.println("姓名：" + e.getElementsByTagName("name").item(0).getFirstChild().getNodeValue());
			System.out.println("邮箱：" + e.getElementsByTagName("email").item(0).getFirstChild().getNodeValue());
		}
	}
}

同样地，dom也可以创建xml文件，示例代码如下：

package com.fcy.xml.dom;

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

public class DOMWrite {
	public static void main(String[] args) throws Exception {
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = factory.newDocumentBuilder();
		Document doc = builder.newDocument();
		Element addresslist = doc.createElement("addresslist");
		Element linkman = doc.createElement("linkman");
		Element name = doc.createElement("name");
		Element email = doc.createElement("email");
		name.appendChild(doc.createTextNode("张三"));
		email.appendChild(doc.createTextNode("zhangsan@sina.com"));
		linkman.appendChild(name);
		linkman.appendChild(email);
		addresslist.appendChild(linkman);
		doc.appendChild(addresslist);
		TransformerFactory tf = TransformerFactory.newInstance();
		Transformer t = tf.newTransformer();
		t.setOutputProperty(OutputKeys.ENCODING, "GBK");
		DOMSource source = new DOMSource(doc);
		StreamResult result = new StreamResult(new File("d://test/output.xml"));
		t.transform(source, result);
		
		
		
	}
}

接下来，看下dom4j是如何进行xml解析的：

要想使用dom4j功能，需要引入dom4j的jar包，相关maven库依赖如下：

<dependency>
	    <groupId>dom4j</groupId>
	    <artifactId>dom4j</artifactId>
	    <version>1.6.1</version>
 </dependency>

引入dom4j的jar包，就可以编写xml解析程序了，首先看一个生成xml文件的示例：

package com.fcy.xml.dom;

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

public class DOMWrite {
	public static void main(String[] args) throws Exception {
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = factory.newDocumentBuilder();
		Document doc = builder.newDocument();
		Element addresslist = doc.createElement("addresslist");
		Element linkman = doc.createElement("linkman");
		Element name = doc.createElement("name");
		Element email = doc.createElement("email");
		name.appendChild(doc.createTextNode("张三"));
		email.appendChild(doc.createTextNode("zhangsan@sina.com"));
		linkman.appendChild(name);
		linkman.appendChild(email);
		addresslist.appendChild(linkman);
		doc.appendChild(addresslist);
		TransformerFactory tf = TransformerFactory.newInstance();
		Transformer t = tf.newTransformer();
		t.setOutputProperty(OutputKeys.ENCODING, "GBK");
		DOMSource source = new DOMSource(doc);
		StreamResult result = new StreamResult(new File("d://test/output.xml"));
		t.transform(source, result);
		
		
		
	}
}

程序运行后，生成的xml文件如下：

<?xml version="1.0" encoding="GBK"?>

<addresslist>
  <linkman>
    <name>张三</name>
    <email>zhangsan@sina.com</email>
  </linkman>
  <linkman>
    <name>李四</name>
    <email>lisi@sina.com</email>
  </linkman>
</addresslist>

接下来，利用dom4j的解析功能，对生成的xml文件进行解析：

package com.fcy.xml.dom;

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

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class DOMRead {
	public static void main(String[] args) throws Exception{
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = null;
		builder = factory.newDocumentBuilder();
		Document doc = null;
		doc = builder.parse("d://test//dom_demo.xml");
		NodeList nl = doc.getElementsByTagName("linkman");
		int length = nl.getLength();
		for(int x = 0; x < length; x++){
			Element e = (Element) nl.item(x);
			System.out.println("姓名：" + e.getElementsByTagName("name").item(0).getFirstChild().getNodeValue());
			System.out.println("邮箱：" + e.getElementsByTagName("email").item(0).getFirstChild().getNodeValue());
		}
	}
}

运行程序，得到的结果如下：

总结：虽然dom与dom4j都能进行xml解析，从性能上来看，dom4j要优于dom，在实际开发中建议使用dom4j.另外，一些开源框架，如spring,hibernate等都是使用dom4j的解析方式。