<?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;

//在學(xué)生管理系統(tǒng)里面，學(xué)生的學(xué)號(hào)是唯一的，姓名有可能重復(fù)
public class StudentManager {
 public static void main(String[] args) {
 try {
 Document doc = Domutils.getDoc(new File("xml文件的相對(duì)路徑"));
 Scanner input = new Scanner(System.in);
 System.out.println("歡迎來(lái)到學(xué)生管理系統(tǒng)\n\n\n請(qǐng)輸入你要進(jìn)行什么操作是：\n1.添加學(xué)生信息\n2.刪除學(xué)生信息\n3.修改學(xué)生信息\n(請(qǐng)輸入前邊的序號(hào))");
 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();
 }
 }
 //修改學(xué)生信息
 private static void updStudent(Document doc) {
 Element updStudent = null;
 Scanner input = new Scanner(System.in);
 System.out.println("請(qǐng)輸入你要修改的學(xué)生的學(xué)號(hào)：");
 String studentid = input.nextLine();
 System.out.println("請(qǐng)輸入新學(xué)生的姓名：");
 String newName = input.nextLine();
 System.out.println("請(qǐng)輸入新學(xué)生的年齡：");
 String newAge = input.nextLine();
 
 //將每一個(gè)學(xué)生的列出來(lái)，for循環(huán)判斷你要修改信息的學(xué)生是哪一個(gè)
 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();
 //對(duì)學(xué)生的name屬性進(jìn)行賦新值
 updStudent.getElementsByTagName("name").item(i).getFirstChild().setNodeValue(newName);
 //對(duì)學(xué)生的age 屬性賦新值
 updStudent.getElementsByTagName("age").item(i).getFirstChild().setNodeValue(newAge);
 
 }else{
 break;
 }
 }
 //找出根元素，將修改后的元素持久化到文件
 Element root = doc.getDocumentElement();
 transform(root);
 System.out.println(updStudent);
 }
 //刪除學(xué)生信息
 private static void delStudent(Document doc) {
 Scanner input = new Scanner(System.in);
 //輸入你要?jiǎng)h除的學(xué)生的 學(xué)號(hào)
 System.out.println("請(qǐng)輸入要?jiǎng)h除學(xué)生的學(xué)號(hào)：");
 String studentid = input.nextLine();
 Element root = doc.getDocumentElement();
 
 //將學(xué)生列成一個(gè)表，進(jìn)行遍歷，找對(duì)應(yīng)學(xué)號(hào)的學(xué)生進(jìn)行刪除
 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("沒(méi)有該學(xué)生");
 break;
 }
 }
 //持久化到文件
 transform(root);
 }
 
 //添加學(xué)生信息
 private static void addStudent(Document doc) {
// System.out.println(doc.getElementsByTagName("student").item(1).getAttributes().getNamedItem("id").getNodeValue());
 Element root = doc.getDocumentElement();
 //從控制臺(tái)輸入
 Scanner input = new Scanner(System.in);
 System.out.println("請(qǐng)輸入學(xué)生的序號(hào)：id = ");
 
 //將學(xué)生放到一個(gè)列表里面，看我們要添加的學(xué)生的學(xué)號(hào)里面是否已經(jīng)有了，如果有，需要將新加入的學(xué)生的學(xué)號(hào)改一下
 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("該序號(hào)學(xué)生表里面已經(jīng)存在，請(qǐng)重新輸入一個(gè)新的序號(hào)：");
 studentid = input.nextLine();
 }else {
 break;
 }
 }
 
 System.out.println("請(qǐng)輸入要添加學(xué)生的姓名：name = ");
 String name_value = input.nextLine();
 System.out.println("請(qǐng)輸入要添加學(xué)生的年齡：age = ");
 String age_value = input.nextLine();
 
 //創(chuàng)建節(jié)點(diǎn)
 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);
 //關(guān)聯(lián)節(jié)點(diǎn)之間的關(guān)系
 root.appendChild(student);
 student.appendChild(name);
 student.appendChild(age);
 student.setAttribute("id", studentid);
 name.appendChild(namText);
 age.appendChild(ageText);
 //持久化到文件
 transform(root);
 
 }
 //持久化到文件的方法
 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 {
　　　　　　//獲取工廠模式
 DocumentBuilderFactory factory = 
 DocumentBuilderFactory.newInstance();
　　　　　　　　//獲取builder對(duì)象
 DocumentBuilder builder = factory.newDocumentBuilder(); 
　　　　　　　　//將要解析文件加載成一個(gè)樹(shù)狀文件，開(kāi)始解析 
 Document document = builder.parse(file);
 return document;
 }
}