2.1 使用JAXP 对 xml文档进行DOM解析

//使用 jaxp 对xml文档进行dom解析
public class Demo2 {

    //必要步骤
    @Test
    public void test() throws Exception {
        
    //1.创建工厂
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
                
    //2.得到dom解析器
        DocumentBuilder db = dbf.newDocumentBuilder();
        
    //3.解析XML文档，得到代表文档的Document
        Document d = db.parse("src/com/xml/javaweb/book.xml");
        
        
    }
}

示例：对xml节点进行增删改查

public class Demo3 {
    //读取XML文件中：<书名>javaWEB</书名>  节点中的值
    @Test
    public void read() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        NodeList list = d.getElementsByTagName("书名");
        Node node = list.item(1);
        String text = node.getTextContent();
        System.out.println(text);
    }    
    
    //遍历整个XML文档中的节点
    @Test
    public void read1() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        //得到根节点
        NodeList list = d.getElementsByTagName("书架");
        Node root = list.item(0);
        list(root);
    }

    private void list(Node root) {
        if(root instanceof Element)
        System.out.println(root.getNodeName());
        
        NodeList nodelist = root.getChildNodes();
        for(int i = 0;i<nodelist.getLength();i++) {
            Node node = nodelist.item(i);
            list(node);
        }
    }
    
    //拿到 name 属性的值
    @Test
    public void read2() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        Element node = (Element) d.getElementsByTagName("书名").item(0);   //node 里面的方法不够用了  没有指定名字得到属性，在知道得到的是Element的情况下  ，把node强转一下
        String att = node.getAttribute("name");
        System.out.println(att);
    }
    
    //向XML文档中添加节点          <售价>39.00元</售价>
    @Test
    public void add() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        //创建节点
        Element element = d.createElement("售价");
        element.setTextContent("39.00元");
        
        //添加节点
        Node node = d.getElementsByTagName("书").item(0);
        node.appendChild(element);
        
        //更新XML文档
        TransformerFactory tff = TransformerFactory.newInstance();
        Transformer tf = tff.newTransformer();
        tf.transform(new DOMSource(d), new StreamResult(new FileOutputStream("src/com/xml/javaweb/book.xml")));
    }
    
    //向XML文档中指定位置添加节点          <售价>39.00元</售价>
    @Test
    public void add2() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        //创建节点
        Element element = d.createElement("售价");
        element.setTextContent("29.00元");
        
        //得到参考节点    
        Element ref = (Element) d.getElementsByTagName("售价").item(0);
        
        //添加节点
        Node node = d.getElementsByTagName("书").item(0);
        
        //往“书”节点的指定位置插入节点
        node.insertBefore(element, ref);    //在参考节点之前插入新建的节点
        
        //更新XML文档
        TransformerFactory tff = TransformerFactory.newInstance();
        Transformer tf = tff.newTransformer();
        tf.transform(new DOMSource(d), new StreamResult(new FileOutputStream("src/com/xml/javaweb/book.xml")));
    }
    
    
    //向XML文档节点上添加属性         <书名> java就业培训课程</书名> 上添加属性  name = "xxxx"
    @Test
    public void add3() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        //得到要添加属性的节点
        Element element= (Element) d.getElementsByTagName("书名").item(0);
        //往指定节点添加属性    
        element.setAttribute("name", "xxxx");
        
        //更新XML文档
        TransformerFactory tff = TransformerFactory.newInstance();
        Transformer tf = tff.newTransformer();
        tf.transform(new DOMSource(d), new StreamResult(new FileOutputStream("src/com/xml/javaweb/book.xml")));
    }
    
    
    //删除XML文档节点          <售价>39.00元</售价>
    @Test
    public void delete() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        //得到要删除的节点
        Element element= (Element) d.getElementsByTagName("售价").item(1);
        //得到要删除的节点的父节点  再调用父节点中删除子节点的方法
        element.getParentNode().removeChild(element);
        
        //更新XML文档
        TransformerFactory tff = TransformerFactory.newInstance();
        Transformer tf = tff.newTransformer();
        tf.transform(new DOMSource(d), new StreamResult(new FileOutputStream("src/com/xml/javaweb/book.xml")));
    }
    
    //更新XML文档节点      <作者>张孝祥</作者> -> <作者>xzk</作者>
    @Test
    public void update() throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document d = db.parse("src/com/xml/javaweb/book.xml");    
        
        //得到要更新的节点
        Element element= (Element) d.getElementsByTagName("作者").item(1);
        //更新该节点的文本
        element.setTextContent("xzk");
        
        //更新XML文档
        TransformerFactory tff = TransformerFactory.newInstance();
        Transformer tf = tff.newTransformer();
        tf.transform(new DOMSource(d), new StreamResult(new FileOutputStream("src/com/xml/javaweb/book.xml")));
    }
}