DOM解析XML

/**
 * 节点类型    NodeType     NamedConstant      nodeName          nodeValue
 * Element     1          ELEMENT_NODE       element name       null
 * Attr        2          ATTRIBUTE_NODE     属性名                          属性值
 * Text        3          TEXT_NODE          #text             节点内容
 * @author Administrator
 *
 */

public class main {

	public static void main(String[] args) {
		
		//创建一个DocumentBuilderFactory的对象
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		try {
			//创建DocumentBuilder对象
			DocumentBuilder db = dbf.newDocumentBuilder();
			//通过DocumentBuilder对象的parser方法加载books.xml文件到当前项目下
			Document document = db.parse("books.xml");
			//获取所有book节点的集合
			NodeList bookList = document.getElementsByTagName("book");
			//通过nodelist的getLength()方法可以获取bookList的长度
			System.out.println("一共有" + bookList.getLength() + "本书");
			//遍历每个book节点
			for (int i = 0; i < bookList.getLength(); i++) {
				System.out.println("=================下面开始遍历第" + (i + 1) + "本书的内容=================");
				//通过 item(i)方法 获取一个book节点，nodelist的索引值从0开始
				Node book = bookList.item(i);
			    //book节点属性集合
				NamedNodeMap attrs = book.getAttributes();
				System.out.println("第 " + (i + 1) + "本书共有" + attrs.getLength() + "个属性");
				//遍历book的属性
				for (int j = 0; j < attrs.getLength(); j++) {
					//获取book节点的某一个属性
					Node attr = attrs.item(j);
					//获取属性名
					System.out.print("属性名：" + attr.getNodeName());
					//获取属性值
					System.out.println("--属性值" + attr.getNodeValue());
				}
//						//前提：已经知道book节点有且只能有1个id属性
//						//将book节点进行强制类型转换，转换成Element类型
//						Element book = (Element) bookList.item(i);
//						//通过getAttribute("id")方法获取属性值
//						String attrValue = book.getAttribute("id");
//						System.out.println("id属性的属性值为" + attrValue);
				//book节点的子节点
				NodeList childNodes = book.getChildNodes();
				//遍历childNodes获取每个节点的节点名和节点值
				System.out.println("第" + (i+1) + "本书共有" + 
				childNodes.getLength() + "个子节点");
				for (int k = 0; k < childNodes.getLength(); k++) {
					//区分出text类型的和lement类型的node
					if (childNodes.item(k).getNodeType() == Node.ELEMENT_NODE) {
						//获取了element类型节点的节点名
						System.out.print("第" + (k + 1) + "个节点的节点名：" 
						+ childNodes.item(k).getNodeName());
						//获取了element类型节点的节点值
						System.out.println("--节点值是：" + childNodes.item(k).getFirstChild().getNodeValue());
						//System.out.println("--节点值是：" + childNodes.item(k).getTextContent());
					}
				}
				System.out.println("======================结束遍历第" + (i + 1) + "本书的内容=================");
			}
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		}  catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
				
	}

}

public class main {
	
	public DocumentBuilder getDocumentBuilder(){
		// 创建一个DocumentBuilderFactory的对象
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		// 创建DocumentBuilder对象
		DocumentBuilder db =null;
		try {
			db = dbf.newDocumentBuilder();
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		}
		return db;
	}
	
	/**
	 * 生成xml
	 */
	public void createXML(){
		
		DocumentBuilder db = getDocumentBuilder();
		Document document = db.newDocument();
		document.setXmlStandalone(true);
		
		Element bookstore = document.createElement("bookStore");
		//向bookstore根节点中添加子节点book
		Element book = document.createElement("book");
		Element name = document.createElement("name");
//		name.setNodeValue("小王子");
		name.setTextContent("小王子");
		
		book.appendChild(name);
		book.setAttribute("id", "1");
		
		//将book节点添加到bookstore根节点中
		bookstore.appendChild(book);
		
		//将bookstore节点（已经包含了book）添加到dom树中
		document.appendChild(bookstore);
		
		//创建TransformerFactory对象
		TransformerFactory tff = TransformerFactory.newInstance();
		try {
			//创建Transformer对象
			Transformer tf = tff.newTransformer();
			tf.setOutputProperty(OutputKeys.INDENT, "yes");
			tf.transform(new DOMSource(document),new StreamResult(new File("books1.xml")));
		} catch (TransformerConfigurationException e) {
			e.printStackTrace();
		} catch (TransformerException e) {
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		main creatXml = new main();
		creatXml.createXML();
	}
}