dom解析XML

DOM(Document Object Model)
			1.文档节点(org.w3c.dom.Document接口)
				public interface Document extends Node {
					public Element getDocumentElement();
//获得文档的根节点
					public Attr createAttribute(String name)throws DOMException;
//创建属性节点
					public Attr createAttributeNS(String namespaceURI,String qualifiedName)
	                throws DOMException;//根据名称空间URL和限定名创建属性节点
	                public CDATASection createCDATASection(String data)throws DOMException;//创建CDATA段
	                public Comment createComment(String data);//创建注释
	                public Element createElement(String tagName)throws DOMException;//创建元素
	                public Element getElementById(String elementId); //根据ID属性的值,获得Element
	                public NodeList getElementsByTagName(String tagname);//根据TagName获得Element的列表NodeList
	                public NodeList getElementsByTagNameNS(String namespaceURI,String localName);//名称空间(同上)
	            }
            2.元素节点(org.w3c.dom.Element接口)
            	public interface Element extends Node{
            		public String getAttribute(String name);//通过属性名获得属性值
            		public Attr getAttributeNode(String name);//获得属性节点
            		public Attr getAttributeNodeNS(String namespaceURI,String localName)
                                   throws DOMException;//获得属性节点(名称空间)
                    public boolean hasAttribute(String name);//是否用属性
                    public void removeAttribute(String name)throws DOMException;//如果删除的属性有缺省值,就出会出现缺省值
                    public void setAttribute(String name,String value)throws DOMException;//为一个元素设置属性
                    public Attr setAttributeNode(Attr newAttr);//增加一个新的属性节点
            	}
            3.文本节点(org.w3c.dom.Text接口)
            	文本节点包括空白
            4.属性节点(org.w3c.dom.Attr接口)
            	public interface Attr extends Node {
            		public String getName();
            		public String getValue();
            		public void setValue(String value)
            		public boolean isId();
            	}
            5.注释节点(org.w3c.dom.Comment接口)
            	public interface Comment extends CharacterData {}
			6.处理指令节点(org.w3c.dom.ProcessingInstruction接口)
				public interface ProcessingInstruction extends Node {}
			7.文档类型节点(org.w3c.dom.DocumentType接口)
				每个Document都有DocumentType属性
				public interface DocumentType extends Node {}
			8.CDATA段节点(org.w3c.dom.CDATASection接口)
				public interface CDATASection extends Text {}
			9.文档片段节点(org.w3c.dom.DocumentFragment接口)
				public interface DocumentFragment extends Node {}
			10.实体节点
				...
			11.NodeList接口
				public interface NodeList {
					public Node item(int index);
					public int getLength();
				}
			12.NamedNodeMap接口(用于属性)
				public interface NamedNodeMap {
					public int getLength();
					public Node getNamedItem(String name);//根据名字返回节点
					public Node item(int index);//根据index返回节点					
				}
				//NodeList和NameNodeMap都是保存的对象的引用,所以对里面的对象进行操作时,会改变XML的结构等...

public class DomTest {
	public static void main(String[] args){
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		System.out.println(dbf.getClass().getName());//查看解释器类型
		try {
			DocumentBuilder db = dbf.newDocumentBuilder();
			Document doc = db.parse(new File("students.xml"));
			NodeList nl = doc.getElementsByTagName("student");//返回一个列表,里面装着这个标签的Node列表
			int length = nl.getLength();//返回有多少个签标
			for(int i=0;i<length;i++){
				Element e = (Element) nl.item(i);//item(int i)表示取这个第几个元素
				Node name = e.getElementsByTagName("name").item(0);
				Node age = e.getElementsByTagName("age").item(0);
				Text nameText = (Text) name.getFirstChild();
				Text ageText = (Text) age.getFirstChild();
				System.out.println("name = "+nameText.getTextContent());//getTextContent()获得文本的内容
				System.out.println("age = "+ageText.getTextContent());
			}
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

public class DomPrint {
	public static void printNodeInfo(Node node){
		System.out.println("nodeName:"+node.getNodeName()+" nodeValue:"+node.getNodeValue());
		//获得Node的姓字和值
	}
	
	public static void printNode(Node node){
		short nodetype = node.getNodeType();//获得Node的获型
		switch(nodetype){
			case Node.PROCESSING_INSTRUCTION_NODE:
				System.out.println("-----------------------PI Start-----------------------");
				printNodeInfo(node);
				System.out.println("-----------------------PI End-----------------------");
				break;
			case Node.ELEMENT_NODE:
				System.out.println("-----------------------Element Start-----------------------");
				printNodeInfo(node);
				System.out.println("-----------------------Element End-----------------------");
				NamedNodeMap att = node.getAttributes();
				int length = att.getLength();
				for(int i=0;i<length;i++){
					Attr attribute = (Attr) att.item(i);
					System.out.println("-----------------------Attr Start-----------------------");
					printNodeInfo(attribute);
					System.out.println("-----------------------Attr Start-----------------------");
				}
				break;
			case Node.TEXT_NODE:
				System.out.println("-----------------------Text Start-----------------------");
				printNodeInfo(node);
				System.out.println("-----------------------Text Start-----------------------");
				break;
			default:
				break;
		}
		Node child = node.getFirstChild();//获得第一个孩子
		while(child!=null){
			printNode(child);
			child=child.getNextSibling();//获得对象的下一个对象,同级
		}
	}
	
	public static void main(String[] args) throws SAXException, IOException, ParserConfigurationException{
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		DocumentBuilder db = dbf.newDocumentBuilder();
		Document doc = db.parse(new File("applicationContext_actions.xml"));
		DomPrint.printNode(doc);		
	}
}

public class DomCRUD {
	public static void main(String[] args){
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		try {
			DocumentBuilder db = dbf.newDocumentBuilder();
			Document doc = db.parse(new File("students.xml"));
			
			Element student = doc.createElement("student");
			Element name = doc.createElement("name");
			Element age = doc.createElement("age");
			//createElement("age");创建标签
			Text nameText = doc.createTextNode("xiaowang");
			Text ageText =doc.createTextNode("26");
			//createTextNode("")创建文本			
			name.appendChild(nameText);
			age.appendChild(ageText);
			//appendChild()添加
			student.appendChild(name);
			student.appendChild(age);
			
			student.setAttribute("sn","03");
			//setAttribute设置属性
			Element root = doc.getDocumentElement();
			//getDocumentElement()获得根元素
			root.appendChild(student);
			
			NodeList nl = doc.getElementsByTagName("student");
			Element delnode = (Element) nl.item(0);
			root.removeChild(delnode);
			//removeChild()删除孩子
			Element editNode = (Element) nl.item(0);
			editNode.setAttribute("sn","01");
			
			Element editName = (Element) editNode.getElementsByTagName("name").item(0);
			Element editAge = (Element) editNode.getElementsByTagName("age").item(0);
			
			editAge.getFirstChild().setNodeValue("19");
			
			for(int i=0;i<nl.getLength();i++ ){
				Element e = (Element) nl.item(i);
				System.out.println(e.getAttribute("sn"));
				Node names = e.getElementsByTagName("name").item(0);
				Node ages = e.getElementsByTagName("age").item(0);
				
				System.out.println(names.getFirstChild().getTextContent());
				System.out.println(ages.getFirstChild().getTextContent());
			}
			//将内存的XML对象树输出到一个文件
			TransformerFactory tff = TransformerFactory.newInstance();
			Transformer tf = tff.newTransformer();
			tf.setOutputProperty("encoding", "utf-8");
			DOMSource doms = new DOMSource(doc);
			StreamResult sr = new StreamResult(new File("newstudent.xml"));
			tf.transform(doms,sr);
			
		} catch (ParserConfigurationException e) {			
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (TransformerConfigurationException e) {
			e.printStackTrace();
		} catch (TransformerException e) {
			e.printStackTrace();
		}
	}
}