xmlファイルを小さいデータベースとして、学生の添削調査の簡単な例を行います。

<?xml version="1.0" encoding="UTF-8"?><Students>
 <student id="2">
  <name>ttt</name>
  <age>44</age>
 </student>
 <student id="3">
  <name>linda2</name>
  <age>22</age>
 </student>
 <student id="4">
  <name>linda3</name>
  <age>23</age>
 </student>
 <student id="5">
  <name>jack</name>
  <age>2</age>
 </student>
 <student id="1">
   <name>yyh1</name>
   <age>22</age>
 </student>
</Students>

import java.io.File;
import java.io.IOException;
import java.util.Scanner;

import javax.xml.parsers.ParserConfigurationException;
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.NodeList;
import org.w3c.dom.Text;
import org.xml.sax.SAXException;

//         ，         ，       
public class StudentManager {
  public static void main(String[] args) {
    try {
      Document doc = Domutils.getDoc(new File("xml       "));
      Scanner input = new Scanner(System.in);
      System.out.println("          


            ：
1.      
2.      
3.      
(        )");
      int num = input.nextInt();
      if(num == 1) {
        addStudent(doc);
      }else if(num == 2) {
        delStudent(doc);
      }else if(num == 3) {
        updStudent(doc);
      }
    } catch (SAXException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    } catch (ParserConfigurationException e) {
      e.printStackTrace();
    }
  }
  //      
  private static void updStudent(Document doc) {
    Element updStudent = null;
    Scanner input = new Scanner(System.in);
    System.out.println("             ：");
    String studentid = input.nextLine();
    System.out.println("         ：");
    String newName = input.nextLine();
    System.out.println("         ：");
    String newAge = input.nextLine();
    
    //          ，for                 
    NodeList list = doc.getElementsByTagName("student");
    for(int i = 0; i <list.getLength(); i++) {
      if(studentid.equals(list.item(i).getAttributes().getNamedItem("id").getNodeValue())){
        updStudent = (Element) doc.getElementsByTagName("student").item(i).getFirstChild().getParentNode();
        //    name       
        updStudent.getElementsByTagName("name").item(i).getFirstChild().setNodeValue(newName);
        //    age      
        updStudent.getElementsByTagName("age").item(i).getFirstChild().setNodeValue(newAge);
        
      }else{
        break;
      }
    }
    //     ，             
    Element root = doc.getDocumentElement();
    transform(root);
    System.out.println(updStudent);
  }
  //      
  private static void delStudent(Document doc) {
    Scanner input = new Scanner(System.in);
    //             
    System.out.println("           ：");
    String studentid = input.nextLine();
    Element root = doc.getDocumentElement();
    
    //        ，    ，            
    NodeList list = doc.getElementsByTagName("student");
    for(int i = 0; i < list.getLength(); i++) {
    if((studentid).equals(list.item(i).getAttributes().getNamedItem("id").getNodeValue())){
      Element delStudent = (Element) doc.getElementsByTagName("student").item(i).getFirstChild().getParentNode(); 
        root.removeChild(delStudent);
        break;
      }else {
        System.out.println("     ");
        break;
      }
    }
    //      
    transform(root);
  }
  
  //      
  private static void addStudent(Document doc) {
//    System.out.println(doc.getElementsByTagName("student").item(1).getAttributes().getNamedItem("id").getNodeValue());
    Element root = doc.getDocumentElement();
    //      
    Scanner input = new Scanner(System.in);
    System.out.println("        ：id = ");
     
    //           ，                    ，   ，               
    NodeList list = doc.getElementsByTagName("student");
    String studentid = input.nextLine();
    for(int i = 0; i < list.getLength(); i++) {
      if(studentid.equals(list.item(i).getAttributes().getNamedItem("id").getNodeValue())){
        System.out.println("            ，           ：");
         studentid = input.nextLine();
      }else {
        break;
      }
    }
    
    System.out.println("           ：name = ");
    String name_value = input.nextLine();
    System.out.println("           ：age = ");
    String age_value = input.nextLine();
    
    //    
    Element student = doc.createElement("student");
    Element name = doc.createElement("name");
    Element age = doc.createElement("age");
    Text namText = doc.createTextNode(name_value);
    Text ageText = doc.createTextNode(age_value);
    //         
    root.appendChild(student);
    student.appendChild(name);
    student.appendChild(age);
    student.setAttribute("id", studentid);
    name.appendChild(namText);
    age.appendChild(ageText);
    //      
    transform(root);
    
  }
  //         
  private static void transform(Element root)
      throws TransformerFactoryConfigurationError {
    TransformerFactory factory = TransformerFactory.newInstance();
    try {
      Transformer tf = factory.newTransformer();
      tf.transform(new DOMSource(root), new StreamResult(new File("src/com/briup/dom/student.xml")));
    } catch (TransformerConfigurationException e) {
      e.printStackTrace();
    } catch (TransformerException e) {
      e.printStackTrace();
    }
  }
}

import java.io.File;
import java.io.IOException;
import java.nio.file.attribute.AclEntry.Builder;

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

import org.w3c.dom.Document;
import org.xml.sax.SAXException;

public class Domutils {
  public static Document getDoc(File file) throws SAXException, IOException, ParserConfigurationException {
　　　　　　//      
    DocumentBuilderFactory factory = 
        DocumentBuilderFactory.newInstance();
　　　　　　　　//  builder  
      DocumentBuilder builder = factory.newDocumentBuilder();  
　　　　　　　　//               ，         
      Document document = builder.parse(file);
    return document;
  }
}