DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();

    DocumentBuilder builder=factory.newDocumentBuilder();
   
    org.w3c.dom.Document document=builder.parse("src/book.xml");

         Element book=document.createElement("book");
         book.setAttribute("id", "004");
         book.setAttribute("type", "动漫专题");
        
         Element bookName=document.createElement("bookName");
         bookName.setTextContent("铠甲勇士");
        
         Element bookPrice=document.createElement("bookPrice");
         bookPrice.setTextContent("20");
        
         Element bookAuthor=document.createElement("bookAuthor");
         bookAuthor.setTextContent("sb");
        
         book.appendChild(bookName);
         book.appendChild(bookPrice);
         book.appendChild(bookAuthor);
        
         document.getElementsByTagName("book").item(0).appendChild(book);
        
         TransformerFactory tran=TransformerFactory.newInstance();
        
         Transformer transformer=tran.newTransformer();
         Source source=new DOMSource(document);
         Result result=new StreamResult("src/book.xml");
         transformer.transform(source, result);
         System.out.println("add ok!!!");