deal with xml

XML现在已经成为一种通用的数据交换格式,它的平台无关性,语言无关性,系统无关性,给数据集成与交互带来了极大的方便。对于XML本身的语法知识与技术细节,需要阅读相关的技术文献,这里面包括的内容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations),具体可参阅w3c官方网站文档http://www.w3.org获取更多信息。
XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已。基本的解析方式有两种,一种叫SAX，另一种叫DOM。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析。

demo.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<employees>
<employee>
<name>Joe</name>
<sex>male</sex>
<age>20</age>
</employee>
</employees>

Dom 1

package xml;
import java.io.*;

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

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


import javax.xml.transform.TransformerFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;

import org.xml.sax.SAXException;

public class DomDemo {
	private Document document;

	public void init() {
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		try {
			DocumentBuilder builder = factory.newDocumentBuilder();
			this.document=builder.newDocument();
		} catch (ParserConfigurationException e) {
			System.out.println(e.toString());
		}
	}

	public void creatXML(String filename){
		Element root=this.document.createElement("employees");
		this.document.appendChild(root);

		Element employee=this.document.createElement("employee");

		Element name=this.document.createElement("name");		
		Node nameNode=this.document.createTextNode("Joe");
		name.appendChild(nameNode);

		employee.appendChild(name);

		Element sex=this.document.createElement("sex");
		Node sexNode=this.document.createTextNode("male");
		sex.appendChild(sexNode);

		employee.appendChild(sex);

		Element age=this.document.createElement("age");
		age.appendChild(this.document.createTextNode("20"));

		employee.appendChild(age);

		root.appendChild(employee);

		TransformerFactory factory=TransformerFactory.newInstance();
		try{
			Transformer transformer=factory.newTransformer();

			DOMSource domSource=new DOMSource(this.document);

			transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
			transformer.setOutputProperty(OutputKeys.INDENT, "yes");

			PrintWriter writer=new PrintWriter(new FileOutputStream(filename));

			StreamResult sr=new StreamResult(writer);

			transformer.transform(domSource, sr);

			System.out.println("生成XML文件成功!");
		}catch (TransformerConfigurationException e) {
			System.out.println(e.getMessage());			
		} catch (IllegalArgumentException e) {
			System.out.println(e.getMessage());
		} catch (FileNotFoundException e) {
			System.out.println(e.getMessage());
		} catch (TransformerException e) {
			System.out.println(e.getMessage());
		}		
	}

	public void parserXML(String filename){
		try{
			DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
			DocumentBuilder builder=factory.newDocumentBuilder();
			Document document=builder.parse(filename);

			NodeList employees=document.getChildNodes();

			for(int i=0;i<employees.getLength();i++){
				Node employee=employees.item(i);
				NodeList employeeInfo=employee.getChildNodes();

				for(int j=0;j<employeeInfo.getLength();j++){
					Node node=employeeInfo.item(j);
					NodeList employeeMeta=node.getChildNodes();

					for(int k=0;k<employeeMeta.getLength();k++){
						System.out.println(employeeMeta.item(k).getNodeName()+":"+
								employeeMeta.item(k).getTextContent());
					}
				}
			}
			System.out.println("解析完毕!");
		}catch (FileNotFoundException e) {
		System.out.println(e.getMessage());
		} catch (ParserConfigurationException e) {
		System.out.println(e.getMessage());
		} catch (SAXException e) {
		System.out.println(e.getMessage());
		} catch (IOException e) {
		System.out.println(e.getMessage());
		} 

	}
	public static void main(String[] args){
		DomDemo demo=new DomDemo();
		demo.init();
		demo.parserXML("demo.xml");
	}
}

Dom 2

package xml;
import   com.sun.org.apache.xerces.internal.parsers.DOMParser;

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

public class TestDOMParser {
	public void parseXMLFile(String fileName){
		try{
			//构造Dom解析器的实例
			DOMParser parser=new DOMParser();
			//将XML文件转换成DOM树存入内存
			parser.parse(fileName);
			Document document=parser.getDocument();
			//获取root节点
			Element root=document.getDocumentElement();

			NodeList employees=root.getElementsByTagName("employee");

			System.out.println("XML文件开始解析");

			for(int i=0;i<employees.getLength();i++){
				//当前employee元素
				Element employee=(Element)employees.item(i);

				NodeList names=employee.getElementsByTagName("name");

				System.out.println("name:"+names.item(0).getFirstChild().getNodeValue());

				NodeList sexs=employee.getElementsByTagName("sex");

				System.out.println("sex:"+sexs.item(0).getFirstChild().getNodeValue());

				NodeList ages=employee.getElementsByTagName("age");

				System.out.println("age:"+ages.item(0).getFirstChild().getNodeValue());
			}

			System.out.println("XML文件解析结束");
		}catch(Exception e){
			System.out.println(e.toString());
		}
	}

	public static void main(String[] args){
		TestDOMParser parser=new TestDOMParser();
		parser.parseXMLFile("demo.xml");
	}
}