JAva解析xmlでよく使われる3つの方法

package com.xcz.xml; 
  
import java.io.File; 
import java.io.IOException; 
import java.util.List; 
  
import javax.xml.parsers.ParserConfigurationException; 
  
import org.xml.sax.SAXException; 
  
import com.xcz.po.User; 
import com.xcz.xml.util.DomUtil; 
  
public class Dom4Xml { 
  
    private DomUtil domUtil = new DomUtil(); 
      
    public static void main(String[] args) { 
        try { 
            File f = new File("src/jdbc-params.xml"); 
            List<User> list = new Dom4Xml().domUtil.parseXml(f); 
            for (User user : list) { 
                System.out.println(user); 
            } 
        } catch (ParserConfigurationException e) { 
            e.printStackTrace(); 
        } catch (SAXException e) { 
            e.printStackTrace(); 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } 
          
    } 
} 

package com.xcz.xml.util; 
  
import java.io.File; 
import java.io.IOException; 
import java.util.ArrayList; 
import java.util.List; 
  
import javax.xml.parsers.DocumentBuilder; 
import javax.xml.parsers.DocumentBuilderFactory; 
import javax.xml.parsers.ParserConfigurationException; 
  
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.xcz.po.User; 
  
public class DomUtil { 
  
    private DocumentBuilderFactory factory; 
    private DocumentBuilder builder; 
    private Document document; 
      
    private List<User> list; 
      
    /** 
     *     DocumentBuilderFactory    
     * @return DocumentBuilderFactory 
     */ 
    private DocumentBuilderFactory getDocumentBuilderFactory(){ 
        return DocumentBuilderFactory.newInstance(); 
    } 
      
    /** 
     *     DocumentBulider    
     * @param DocumentBuilderFactory fac  
     * @return DocumentBuilder 
     * @throws ParserConfigurationException 
     */ 
    private DocumentBuilder getDocumentBuilder(DocumentBuilderFactory fac) throws ParserConfigurationException{ 
        return fac.newDocumentBuilder(); 
    } 
      
    /** 
     *   ：  XML   
     * @param file xml   
     * @return List<User> 
     * @throws ParserConfigurationException 
     * @throws SAXException 
     * @throws IOException 
     */ 
    public List<User> parseXml(File file) throws ParserConfigurationException, SAXException, IOException{ 
        factory = getDocumentBuilderFactory(); 
        builder = getDocumentBuilder(factory); 
        document = builder.parse(file); 
        List<User> list = parseXmlProcess(document); 
        return list; 
    } 
      
    /** 
     *   ：xml         
     * @param document 
     * @return List<User> 
     */ 
    private List<User> parseXmlProcess(Document document){ 
        list = new ArrayList<User>(); 
          
        //      
        Element root = document.getDocumentElement(); 
        //               
        NodeList childNodes = root.getChildNodes(); 
          
        for(int i=0; i<childNodes.getLength(); i++){//        ：getLength() 
            Node node = childNodes.item(i);//   index   ：item(index) 
              
            if("person".equals(node.getNodeName())){//      tagName:getNodeName() 
                NodeList pChildNodes = node.getChildNodes(); 
              
                for(int p=0; p<pChildNodes.getLength(); p++){ 
                    Node pNode = pChildNodes.item(p); 
                  
                    if("user".equals(pNode.getNodeName())){ 
                        User user = new User(); 
                        NodeList uChildNodes = pNode.getChildNodes(); 
                      
                        for(int u=0;u<uChildNodes.getLength();u++){ 
                              
                            Node uNode = uChildNodes.item(u); 
                          
                            if("username".equals(uNode.getNodeName())){ 
                                user.setUsername(uNode.getTextContent());//           ：getTextContent() 
                            } 
                            if("password".equals(uNode.getNodeName())){ 
                                user.setPassword(uNode.getTextContent()); 
                            } 
                            if("birthday".equals(uNode.getNodeName())){ 
                                user.setBirthday(uNode.getTextContent()); 
                            } 
                        } 
                        list.add(user); 
                    } 
                } 
            } 
        } 
          
        return list; 
    } 
}