使用JAXP对XML文档进行DOM解析

private static String filename="src/exam.xml"; 
    public static Document getDocument() throws Exception{
         //1创建工厂
        DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
        //2得到dom解析器对象
        DocumentBuilder builder=factory.newDocumentBuilder();
        //3解析xml文档，得到代表文档的document
        return builder.parse(filename);
        
    }

public static void writeXml(Document document) throws TransformerException{
        TransformerFactory factory=TransformerFactory.newInstance();
        Transformer tf=factory.newTransformer();
        //transform(Source xmlSource, Result outputTarget)
        tf.transform(new DOMSource(document), new StreamResult(filename) );
    }

<?xml version="1.0" encoding="UTF-8" standalone="no"?><书架>
    <书>
         <书名 name="xxx">影响力</书名>
         <作者>罗伯特.西奥迪尼</作者>
     
     <售价>90</售价>
     </书>
         <书>
         <书名>JavaScript</书名>
         <作者>JS</作者>
         <售价>45</售价>
         </书>
</书架>

@Test
    public  void read() throws ParserConfigurationException, SAXException, IOException {
        DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
        DocumentBuilder builder=factory.newDocumentBuilder();
        Document document=builder.parse("src/books.xml");
        NodeList list= document.getElementsByTagName("书名");
        Node node= list.item(0);
        String content=node.getTextContent();
        System.out.println(content);
    }

    @Test
    public  void read1() throws ParserConfigurationException, SAXException, IOException {
        DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
        DocumentBuilder builder=factory.newDocumentBuilder();
        Document document=builder.parse("src/books.xml");
        Node root=document.getElementsByTagName("书架").item(0);
        list(root);        
    }
    /*
     * 递归遍历XML文件中的所有节点
     * */
    public  void list(Node node){
        if(node instanceof Element){
        System.out.println(node.getNodeName());
        }
        NodeList childs= node.getChildNodes();
        for(int i=0;i<childs.getLength();i++){
            Node child=childs.item(i);
            list(child);
        }
    }

    @Test
    public  void add() throws ParserConfigurationException, SAXException, IOException, TransformerException{
        DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
        DocumentBuilder builder=factory.newDocumentBuilder();
        Document document=builder.parse("src/books.xml");
        Element price=document.createElement("售价");
        //创建节点
        //把创建的节点添加到第一本书
        price.setTextContent("90");
        Element book=(Element) document.getElementsByTagName("书").item(0);
        book.appendChild(price);
        //把更新后的文档
        TransformerFactory tfactory=TransformerFactory.newInstance();
        Transformer tf=tfactory.newTransformer();
        tf.transform(new DOMSource(document), new StreamResult("src/books.xml"));
    }

    @Test
    public  void addAttr() throws ParserConfigurationException, SAXException, IOException, TransformerException{
        DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
        DocumentBuilder builder=factory.newDocumentBuilder();
        Document document=builder.parse("src/books.xml");
        Element bookname=(Element) document.getElementsByTagName("书名").item(0);
        bookname.setAttribute("name", "xxx");
        //把更新后的文档
        TransformerFactory tfactory=TransformerFactory.newInstance();
        Transformer tf=tfactory.newTransformer();
        tf.transform(new DOMSource(document), new StreamResult("src/books.xml"));
    }

@Test
    public  void delete() throws ParserConfigurationException, SAXException, IOException, TransformerException{
        DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
        DocumentBuilder builder=factory.newDocumentBuilder();
        Document document=builder.parse("src/books.xml");
        Element bookname=(Element) document.getElementsByTagName("售价").item(0);
        //把更新后的文档
        Element e=(Element) document.getElementsByTagName("书").item(0);
        e.removeChild(bookname);
        TransformerFactory tfactory=TransformerFactory.newInstance();
        Transformer tf=tfactory.newTransformer();
        tf.transform(new DOMSource(document), new StreamResult("src/books.xml"));
    }