父、祖父节点

首先引出要解析的xml文件：

<?

xml version="1.0" encoding="UTF-8"?

><书架>

	<书>

		<书名>javaweb开发</书名>

		<作者 id="12">张孝祥</作者>

		<售价>59元</售价>

	</书>

	<书>

		<书名>JavaScript网页开发</书名>

		<作者>张孝祥</作者>

		<售价>28.00元</售价>

	</书>

</书架>

下面即是对xml的增删改查操作：

import java.io.FileOutputStream;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.transform.Transformer;

import javax.xml.transform.TransformerConfigurationException;

import javax.xml.transform.TransformerFactory;

import javax.xml.transform.dom.DOMSource;

import javax.xml.transform.stream.StreamResult;

import org.junit.Before;

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 Demo3 {

	/**

	 * 利用dom完毕文档的crud

	 * @param args

	 * @throws Exception

	 * @throws ParserConfigurationException

	 * @throws Exception

	 * @throws SAXException

	 * @throws Exception

	 */

	private Document document;

	@Before

	public void before() throws Exception{

		//获得dom解析工厂类

		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

		//得到dom解析器

		DocumentBuilder builder = factory.newDocumentBuilder();

		//解析xml文件

		document = builder.parse("src/book.xml");

	}

	//遍历

	@Test

	public void listXml() throws ParserConfigurationException, SAXException, Exception{

		list(document);

	}

	public void list(Node node){

		//打印结点的名称

		System.out.println(node.getNodeName());

		//获得全部子节点

		NodeList list = node.getChildNodes();

		for(int i=0;i<list.getLength();i++){

			Node child = list.item(i);

			//递归整个dom树

			list(child);

		}

	}

	//读取书名节点的值：<书名>javaweb开发</书名>

	@Test

	public void test1(){

		Document document = this.document;

		Node node = document.getElementsByTagName("书名").item(0);

		String value = node.getTextContent();

		System.out.println(value);

	}

	//读取书名属性的值：<售价 type="rmb">39.00元</售价>

	@Test

	public void test2(){

		Document document = this.document;

		Node node = document.getElementsByTagName("售价").item(0);

		Element price =  (Element) node;   //发现node满足不了。把node强转成对应类型

		String attValue = price.getAttribute("type");

		System.out.println(attValue);

	}

	//向xml文档中加入售价节点

	@Test

	public void test3() throws Exception{

		Document document = this.document;

		//创建要挂的节点

		Element price = document.createElement("售价");

		price.setTextContent("59元");

		//把创建的结点挂到书节点下

		Node book = document.getElementsByTagName("书").item(0);

		book.appendChild(price);

		//把内存中更新后对象树，又一次定回到xml文档中

		TransformerFactory factory = TransformerFactory.newInstance();

		Transformer tf = factory.newTransformer();

		tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/book.xml")));

	}

	//向xml文档中指定位置上加入售价节点

	@Test

	public void test4() throws Exception{

		Document document = this.document;

		//创建要加入的节点

		Element price = document.createElement("售价");

		price.setTextContent("59元");

		//得到要向哪个节点上挂子节点

		Node book = document.getElementsByTagName("书").item(0);

		//向參考节点前，挂新节点

		book.insertBefore(price, document.getElementsByTagName("售价").item(0));

		//把内存中更新后对象树，又一次定回到xml文档中

		TransformerFactory factory = TransformerFactory.newInstance();

		Transformer tf = factory.newTransformer();

		tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/book.xml")));

	}

	//向xml文档加入节点属性

	@Test

	public void test5() throws Exception{

		Document document = this.document;

		//得到要加入属性的节点

		Element author = (Element) document.getElementsByTagName("作者").item(0);

		author.setAttribute("id", "12");  //向节点挂属性

		//把内存中更新后对象树，又一次定回到xml文档中

		TransformerFactory factory = TransformerFactory.newInstance();

		Transformer tf = factory.newTransformer();

		tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/book.xml")));

	}

	//删除xml文档中的售价节点

	@Test

	public void test6() throws Exception{

		Document document = this.document;

		//得到要删除的节点

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

		//得到要删除的节点的父亲

		Node parent = document.getElementsByTagName("书").item(0);

		parent.removeChild(price);

		//把内存中更新后对象树，又一次定回到xml文档中

		TransformerFactory factory = TransformerFactory.newInstance();

		Transformer tf = factory.newTransformer();

		tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/book.xml")));

	}

	//删除2   : 删除售价节点所在的书结点

	@Test

	public void test7() throws Exception{

		Document document = this.document;

		//得到要删除的节点

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

		price.getParentNode().getParentNode().removeChild(price.getParentNode());

		//把内存中更新后对象树。又一次定回到xml文档中

		TransformerFactory factory = TransformerFactory.newInstance();

		Transformer tf = factory.newTransformer();

		tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/book.xml")));

	}

	@Test

	public void test8() throws Exception{

		Document document = this.document;

		document.getElementsByTagName("售价").item(1).setTextContent("19元");

		//把内存中更新后对象树。又一次定回到xml文档中

		TransformerFactory factory = TransformerFactory.newInstance();

		Transformer tf = factory.newTransformer();

		tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/book.xml")));

	}

}