学步园

package com.test;

import java.io.ByteArrayOutputStream;
import java.io.StringReader;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
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;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

public class xmlHandle {

	private Document document;
	private String xmlStr; 
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		xmlHandle handler = new xmlHandle();
		try {
			handler.geneXmlByDom();
			
			handler.getXmlFromString();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public void geneXmlByDom() throws Exception {  
        //step1:获得一个DocumentBuilderFactory  
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();  
        //step2:获得一个DocumentBuilder  
        DocumentBuilder db = factory.newDocumentBuilder();  
        //step3:新建一个Document对象  
        document = db.newDocument();  
        //step4:创建一个根节点  
        Element rootElement = document.createElement("Persons");  
        for (int i=0;i<5;i++) {  
            //step5:创建一个节点  
            Element person = document.createElement("person");  
            //step6:为该节点设定属性  
            person.setAttribute("id", "id_"+i);  
            Element name = document.createElement("name");  
            //为节点设定文本内容  
            name.setTextContent("name_"+i);  
            Element address = document.createElement("address");  
            address.setTextContent("address_"+i);  
            Element email = document.createElement("email");  
            email.setTextContent("email_"+i);  
            person.appendChild(name);  
            person.appendChild(address);  
            person.appendChild(email);  
            //step7:为某一元素节点设立子节点  
            rootElement.appendChild(person);  
        }  
        //step8:把刚刚建立的根节点添加到document对象中  
        document.appendChild(rootElement);  
        //step9:获得一个TransformerFactory对象  
        TransformerFactory transformerFactory = TransformerFactory.newInstance();  
        //step10:获得一个Transformer对象  
        Transformer transformer = transformerFactory.newTransformer();  
        //step11:把document对象用一个DOMSource对象包装起来  
        transformer.setOutputProperty("encoding", "utf-8");
        
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        transformer.transform(new DOMSource(document), new StreamResult(bos));
        xmlStr = bos.toString();
        
        System.out.println(xmlStr);    
    } 
	
	public void getXmlFromString() throws Exception{
		StringReader sr = new StringReader(xmlStr); 
		InputSource is = new InputSource(sr); 
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); 
		DocumentBuilder builder=factory.newDocumentBuilder(); 
		Document document = builder.parse(is);
        NodeList nodeList = document.getElementsByTagName("person");  
        for (int i=0;i<nodeList.getLength();i++) {  
            //因为这里我知道它就是一个Element对象，所以进行了强转  
            Element person = (Element)nodeList.item(i);  
            //获得Element对象的属性  
            String id = person.getAttribute("id");  
            //因为这里我知道只有一个对象，所以就直接item(0)了，  
            //因为Dom是把每个对象都看做是一个节点的，所以如果在item(0)的时候直接取getNodeValue()是取不到值的，  
            //只有是TextNode的时候用那个方法才可以取到值，如果想直接取值就用getTextContent()  
            String name = person.getElementsByTagName("name").item(0).getTextContent();  
            String address = person.getElementsByTagName("address").item(0).getTextContent();  
            String email = person.getElementsByTagName("email").item(0).getTextContent();  
            System.out.println(" id = "+id+" \r\n name = "+name+" \r\n address = "+address+" \r\n email = "+email);  
            System.out.println("-------------------------------------");  
        }  
	}	
}