XML解析之DOM解析

      为 XML 文档的已解析版本定义了一组接口。解析器读入整个文档，然后构建一个驻留内存的树结构，然后代码就可以使用 DOM 接口来操作这个树结构。优点：整个文档树在内存中，便于操作；支持删除、修改、重新排列等多种功能；缺点：将整个文档调入内存（包括无用的节点），浪费时间和空间；使用场合：一旦解析了文档还需多次访问这些数据；硬件资源充足（内存、CPU）。

package xml;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
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;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class XMPParser{
	
	private Document document ;
	
	private static String fileName = "C:/Users/Administrator/Desktop/TestXml.xml";
	
	//执行方法
	public static void main(String[] args){
		
		XMPParser parser = new XMPParser();
		parser.init();
		
		//创建XML文件
		//parser.createXML(fileName);
		
		//解析XML文件
		parser.parserXML(fileName);
	}
	
	//初始化方法
	public void init()
	{
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		try {
			DocumentBuilder db = dbf.newDocumentBuilder();
			this.document = db.newDocument();
			
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		}
		
	}
	
	//创建XML文件
	public void createXML(String fileName)
	{
		//创建根节点employees
		Element root = this.document.createElement("employees");
		this.document.appendChild(root);
		
		//创建employee子节点
		Element employe = this.document.createElement("employee");
		
		//创建employee子节点中的name节点
		Element name = this.document.createElement("name");
		//创建name子节点的文本值
		name.setAttribute("style", "green");
		name.appendChild(this.document.createTextNode("刘兴超"));
		
		//把name子节点封装到employee节点中
		employe.appendChild(name);
		
		/**
		 * 创建sex节点
		 */
		Element sex = this.document.createElement("sex");
		sex.appendChild(this.document.createTextNode("girl"));
		employe.appendChild(sex);
		
		/**
		 * 创建age节点
		 */
		Element age = this.document.createElement("age"); 
		age.appendChild(this.document.createTextNode("30")); 
		employe.appendChild(age);
		
		//把employe子节点封装到root根节点下
		root.appendChild(employe);
		
		TransformerFactory tf = TransformerFactory.newInstance(); 
		
		try {
			Transformer transformer = tf.newTransformer();
			
			DOMSource source = new DOMSource(document); 
			
			transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312");
			
			transformer.setOutputProperty(OutputKeys.INDENT, "yes"); 
			
			PrintWriter pw;
			try {
				pw = new PrintWriter(new FileOutputStream(fileName));
				StreamResult result = new StreamResult(pw); 
				
				transformer.transform(source, result); 
				
				System.out.println("生成XML文件成功!"); 
			} catch (FileNotFoundException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (TransformerException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} 
			
	
		} catch (TransformerConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	//解析XML文件
	public void parserXML(String fileName) {
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		try {
			DocumentBuilder db = dbf.newDocumentBuilder();
			Document document = db.parse(fileName);
			
			NodeList employes = document.getChildNodes();
			
			for(int i = 0 ; i< employes.getLength();i++)
			{
				Node node = employes.item(i);
				System.out.println("node 1 =" + node.getNodeName());
				NodeList employeeMeta = node.getChildNodes();
				for (int k = 0; k < employeeMeta.getLength(); k++) 
				{ 
					Node noded = employeeMeta.item(k);
					System.out.println("node 2 =" + noded.getNodeName());
					String nodeName = noded.getNodeName();
					String TextContent = noded.getTextContent();
					System.out.print(nodeName + ":" + TextContent);
					System.out.println();
					} 
			}
			
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}
}