(备忘录)xml文件的生成和解析_DOM_1

xml的解析一般分为两种方式，一种是SAX事件流的方式，另外一种是基于DOM的xml文档树结构解析，SAX是一边解析一边加载，而DOM需要一次性将XML文件全部加载到内存中，再解析构建成文档数的模式。

首先看一下基于DOM的XML解析和创建。


案例xml内容：

引用

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<employees>
<employee>
<name>ddviplinux</name>
<sex>m</sex>
<parents>
<father>xxx</father>
<mother>yyy</mother>
</parents>
</employee>
</employees>

1.首先定一个方法接口：

import org.w3c.dom.Document;

public interface XmlDocument {
	
	public void createDocument(String fileName);
	
	public void parserDocument(String fileName);

}

里面包含了创建和解析的方法定义。

2.实现这个接口：

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.TransformerFactoryConfigurationError;
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;

import com.ailk.xmlparserdemon.intf.XmlDocument;

public class DomXmlDemon implements XmlDocument {
	Document document;
	static String fileName;
	
	public void init(){
		try {
			DocumentBuilderFactory builderFactory=DocumentBuilderFactory.newInstance();
			DocumentBuilder builder=builderFactory.newDocumentBuilder();
[b]			this.document=builder.newDocument();[/b]		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		}
	}
	
	/**
	 * DOM方式生成xml文件
	 */
	public void createDocument(String fileName) {
		Element root=this.document.createElement("employees");
		this.document.appendChild(root);
		
		Element employee=this.document.createElement("employee");
		Element name=this.document.createElement("name");
		name.appendChild(this.document.createTextNode("ddviplinux"));
		employee.appendChild(name);
		
		Element sex=this.document.createElement("sex");
		sex.appendChild(this.document.createTextNode("m"));
		employee.appendChild(sex);
		
		Element parents=this.document.createElement("parents");
		
		
		Element father=this.document.createElement("father");
		father.appendChild(this.document.createTextNode("xxx"));
		parents.appendChild(father);
		
		Element mother=this.document.createElement("mother");
		mother.appendChild(this.document.createTextNode("yyy"));
		parents.appendChild(mother);
		
		employee.appendChild(parents);
		root.appendChild(employee);
		
		
		try {
			DOMSource source=new DOMSource(this.document);
			TransformerFactory tf=TransformerFactory.newInstance();
			Transformer transf=tf.newTransformer();
			transf.setOutputProperty(OutputKeys.ENCODING, "UTF-8");//设置编码格式
			transf.setOutputProperty(OutputKeys.INDENT, "yes");//设置是否在格式化时添加多于的空格
			PrintWriter pw=new PrintWriter(new FileOutputStream(fileName));
			StreamResult result=new StreamResult(pw);
			transf.transform(source, result);
			System.out.println("生成文件成功:"+fileName);
		} catch (TransformerConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (TransformerFactoryConfigurationError e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (TransformerException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}

	public void parserDocument(String fileName) {
		
		try {
			DocumentBuilderFactory dbf=DocumentBuilderFactory.newInstance();
			DocumentBuilder db=dbf.newDocumentBuilder();
[b]			Document document=db.parse(fileName);[/b]			
			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 (ParserConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}
	
	public static void main(String[] args){
		DomXmlDemon dom=new DomXmlDemon();
		DomXmlDemon.fileName="E:\\OneNote\\dom.xml";
		dom.init();
		dom.createDocument(fileName);
		dom.parserDocument(fileName);
	}

}

从上面的实现方法中，我们可以看出来，不管是在解析或者是生成的时候，首先都需要或许到一个documentbuilder,而这里面用到了一个工厂方法，直接获取：

DocumentBuilderFactory dbf=DocumentBuilderFactory.newInstance();
DocumentBuilder db=dbf.newDocumentBuilder();