java实现XML增加元素操作简单示例

package Day01;
import java.io.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.*;
public class CRUDDEMO {
  /*public void addElement() throws Exception{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    Document doc = builder.parse(new File ("src/Day01/Book.xml"));
    Element newEle = doc.createElement("作者");
    newEle.setTextContent("ZC");
    Node nod = doc.getElementsByTagName("书").item(0);
    nod.appendChild(newEle);
    Source sour = new DOMSource(doc);
    Result result = new StreamResult (new FileOutputStream("src/Day01/Book.xml"));
    write (sour, result);
  }*/
  public void addElement2() throws Exception{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); //建立工厂
    DocumentBuilder builder = factory.newDocumentBuilder(); //拿到builder
    Document doc = builder.parse(new File ("src/Day01/Book.xml")); //获得document，这是终极目的
    Element newEle = doc.createElement("作者");// 创建新元素/标签
    newEle.setTextContent("ZC"); //给元素设置内容 <作者>ZC</作者>
    Node nod = doc.getElementsByTagName("书名").item(0); //通过nodelist的item()方法获得具体节点
    /**
     * 在具体节点插入元素用 节点.insertBefore方法
     * 第一个参数是要插入的新节点，第二个是插入的位置
     */
    nod.insertBefore(newEle, doc.getElementsByTagName("书名").item(0));
    /**
     * DOMSource(Node n)
     * 注意 element是Node的一个子类，所以可以把doc放入构造函数
     *
     *
     */
    Source sour = new DOMSource(doc);
    Result result = new StreamResult (new FileOutputStream("src/Day01/Book.xml"));
    write (sour, result);
  }
  public void write(Source source,Result result) {
    TransformerFactory tffactory = TransformerFactory.newInstance();
    Transformer tr;
    try {
      tr = tffactory.newTransformer();
      tr.transform(source, result);
    } catch (TransformerConfigurationException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (TransformerException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
  public static void main(String[] args) throws Exception {
    CRUDDEMO cr = new CRUDDEMO();
    cr.addElement2();
  }
}

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<书架>
  <书>
    <书名>Thinking in Java</书名>
    <作者>Eric</作者>
    <售价>$34</售价>
  </书>
</书架>

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<书架>
  <书>
    <作者>ZC</作者>
    <书名>Thinking in Java</书名>
    <作者>Eric</作者>
    <售价>$34</售价>
  </书>
</书架>