使用jaxp对比xml进行DOM解析

/*DOM解析编程

•遍历所有节点

•查找某一个节点

•删除结点

•更新结点

•添加节点

/*

package cn.itcast.jaxp;

import java.io.File;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.junit.Test;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class Demo1 {

    /**使用jaxp操作xml文档
     * @param args
     * @throws ParserConfigurationException
     * @throws IOException
     * @throws SAXException
     */
    public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {

        //1.获取工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

        //2.产生解析器
        DocumentBuilder builder = factory.newDocumentBuilder();

        //3.解析xml文档，得到代表文档的document
        Document document = builder.parse(new File("src/book1.xml"));

        //遍历
        list(document);
    }

    //得到售价结点的值
    @Test
    public void read() throws Exception{

        //1.获取工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document document = builder.parse(new File("src/book.xml"));

        NodeList list = document.getElementsByTagName("售价");
        Node price = list.item(0);

        String value = price.getTextContent();
        System.out.println(value);
    }

    //修改结点的值:<售价>39.00元</售价>改为109
    @Test
    public  void update() throws Exception{

        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder  builder = factory.newDocumentBuilder();
        Document document = builder.parse(new File("src/book1.xml"));

        Node price = document.getElementsByTagName("售价").item(0);
        price.setTextContent("109");

        //把内存中的document写到xml文档
        TransformerFactory tf = TransformerFactory.newInstance();
        //得到转换器
        Transformer ts = tf.newTransformer();
        ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
    }

    //向指定节点中增加孩子节点（售价节点）
    @Test
    public void add() throws Exception{
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder  builder = factory.newDocumentBuilder();
        Document document = builder.parse(new File("src/book1.xml"));

        //创建需要增加的节点
        Node price = document.createElement("售价");
        price.setTextContent("59元");

        //得到需要增加的节点的父亲
        Node parent = document.getElementsByTagName("书").item(0);

        //把需要增加的节点挂到父结点上
        parent.appendChild(price);

        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer ts = tf.newTransformer();
        ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));

    }

    //向指定位置上插入售价节点
    @Test
    public void add2() throws Exception{
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder  builder = factory.newDocumentBuilder();
        Document document = builder.parse(new File("src/book1.xml"));

        Node node = document.createElement("售价");
        node.setTextContent("39元");

        Node parent = document.getElementsByTagName("书").item(0);
        parent.insertBefore(node, document.getElementsByTagName("书名").item(0));

        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer ts = tf.newTransformer();
        ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
    }

    //删除xml文档的售价结点
    @Test
    public void delete() throws Exception{
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder  builder = factory.newDocumentBuilder();
        Document document = builder.parse(new File("src/book1.xml"));

        Node node = document.getElementsByTagName("售价").item(2);
        node.getParentNode().removeChild(node);
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer ts = tf.newTransformer();
        ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
    }

    //操作xml文档属性
    @Test
    public void updateAttribute() throws Exception{
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder  builder = factory.newDocumentBuilder();
        Document document = builder.parse(new File("src/book1.xml"));

        //操作xml文档的元素时，一般都把元素当作node对象，但是程序员如果发现node不好使时，就应把node强转成相应类型
        Node node  = document.getElementsByTagName("书").item(0);
        Element book = null;
        if(node.getNodeType()==Node.ELEMENT_NODE){  //在作结点转换之前，最好先判断结点类型
            book  = (Element)node;
        }

        book.setAttribute("name", "yyyyyyy");
        book.setAttribute("password", "123");
        book.removeAttribute("password");

        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer ts = tf.newTransformer();
        ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
    }

    //遍历
    public static void list(Node node){

        if(node.getNodeType()==Node.ELEMENT_NODE){
            System.out.println(node.getNodeName());
        }

        NodeList list = node.getChildNodes();
        for(int i=0;i<list.getLength();i++){
            Node child = list.item(i);
            list(child);
        }
    }

}