xml文件的三种解析dom，SAX和dom4j

布满荆棘的人生 2022-05-11 03:24 200阅读 0赞

**目录**

一、XML文件

二、DOM解析

三、SAX解析

四、dom4j解析

--------------------

# 一、XML文件 #

student.xml

<?xml version="1.0" encoding="UTF-8"?>
    
    <!DOCTYPE students
    	[
    		<!ELEMENT students (student*)>
    		<!ELEMENT student (name,age,gender)>
    		<!ELEMENT name (#PCDATA)>
    		<!ELEMENT age (#PCDATA)>
    		<!ELEMENT gender (#PCDATA)>
    		<!ATTLIST student 
    			id ID #REQUIRED
    			sex (male|female) #REQUIRED
    			pid IDREFS #REQUIRED
    		>
    	]
    >
    
    
    <students>
    	<student id="a1" sex="male" pid="a1 a2">
    		<name>Tom</name>
    		<age>20</age>
    		<gender>male</gender>
    	</student>
    	<student id="a2" sex="male" pid="a1">
    		<name>Bob</name>
    		<age>20</age>
    		<gender>male</gender>
    	</student>
    </students>

# 二、DOM解析 #

/**
    	 * 使用dom解析xml文件
    	 * 
    	 * @param path xml文件路径
    	 * 
    	 * @throws Exception
    	 */
    
    	public static void domParse(String path) throws Exception {
    		// 1.创建解析器的工厂类
    		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    		// 2.创建解析器对象
    		DocumentBuilder documentBuilder = factory.newDocumentBuilder();
    		// 3.解析文件获取文档对象
    		Document document = documentBuilder.parse(path);
    		// 4.获取文档根节点
    		Element root = document.getDocumentElement();
    		System.out.println("<" + root.getNodeName() + ">");
    		// 5.获取根节点下面的所有子节点
    		NodeList firstList = root.getChildNodes();
    		for (int i = 0; i < firstList.getLength(); i++) {
    			// node对应每一个节点,一级节点，下面包含很多二级节点
    			Node node = firstList.item(i);
    			// System.out.println("一级节点："+node.getNodeName());
    
    			// 取每一个结点的属性值
    			// NamedNodeMap attributes = node.getAttributes();
    			// if (attributes != null && attributes.getLength() != 0) {
    			// for (int j = 0; j < attributes.getLength(); j++) {
    			// // 对于每个属性
    			// Node item = attributes.item(j);
    			// // System.out.println(item.getNodeName() +"----"+ item.getNodeType());
    			// }
    			// }
    
    			System.out.println("\t<" + node.getNodeName() + " " + node.getAttributes().item(0).getNodeName() + "='"
    					+ node.getAttributes().item(0).getTextContent() + "' " + node.getAttributes().item(1).getNodeName()
    					+ "='" + node.getAttributes().item(1).getTextContent() + "' "
    					+ node.getAttributes().item(2).getNodeName() + "='" + node.getAttributes().item(2).getTextContent()
    					+ "'>");
    			// 取出所有二级节点
    			NodeList secondList = node.getChildNodes();
    			for (int j = 0; j < secondList.getLength(); j++) {
    				// 取出每一个二级节点
    				Node item = secondList.item(j);
    				// System.out.println("二级节点："+item.getNodeName());
    				System.out.println(
    						"\t\t<" + item.getNodeName() + ">" + item.getTextContent() + "</" + item.getNodeName() + ">");
    			}
    			System.out.println("\t</" + node.getNodeName() + ">");
    		}
    		System.out.println("</" + root.getNodeName() + ">");
    	}

/**
    	 * 写xml格式的内容到文件
    	 * 
    	 * @param path
    	 *            文件路径
    	 * @throws Exception
    	 **/
    	public static void domWriter(String path) throws Exception {
    		// 1.创建解析器对象工厂
    		DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
    		// 2.创建解析器对象
    		DocumentBuilder documentBuilder = builderFactory.newDocumentBuilder();
    		// 3.构建文档对象
    		Document dom = documentBuilder.newDocument();
    		// 4.创建根节点
    		Element root = dom.createElement("students");
    			// 5.创建其他节点
    
    			Element firstNode = dom.createElement("student");
    				// 二级节点：name:Tom
    				Element nameNode = dom.createElement("name");
    				nameNode.setTextContent("Tom");
    				// 二级节点：age:20
    				Element ageNode = dom.createElement("age");
    				ageNode.setTextContent("20");
    				// 二级节点：gender:male
    				Element genderNode = dom.createElement("gender");
    				genderNode.setTextContent("male");
    			Element secondNode = dom.createElement("student");
    				// 二级节点：name:Bob
    				Element nameNode1 = dom.createElement("name");
    				nameNode1.setTextContent("Bob");
    				// 二级节点：age:18
    				Element ageNode1 = dom.createElement("age");
    				ageNode1.setTextContent("18");
    				// 二级节点：gender:female
    				Element genderNode1 = dom.createElement("gender");
    				genderNode1.setTextContent("female");
    
    		// 进行结点关联
    		// 关联根节点
    		dom.appendChild(root);
    		// 关联一级节点
    		root.appendChild(firstNode);
    		root.appendChild(secondNode);
    		// 关联二级节点
    		firstNode.appendChild(nameNode);
    		firstNode.appendChild(ageNode);
    		firstNode.appendChild(genderNode);
    
    		secondNode.appendChild(nameNode1);
    		secondNode.appendChild(ageNode1);
    		secondNode.appendChild(genderNode1);
    		
    		//创建转化器对象工厂
    		TransformerFactory factory = TransformerFactory.newInstance();
    		//创建转化器对象
    		Transformer transformer = factory.newTransformer();
    		//执行转化方法
    		transformer.transform(new DOMSource(dom), new StreamResult(new File(path)));
    		
    	}

# 三、SAX解析 #

/**
    	 * SAX解析xml文件的方法
    	 * 
    	 * @param path
    	 *            需要解析的xml文件的路径
    	 * @throws Exception 
    	 */
    	public static void saxParse(String path) throws Exception {
    		//1.构建SAX解析器工厂
    		SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
    		//2.构建解析器对象
    		SAXParser saxParser = saxParserFactory.newSAXParser();
    		//3.调用方法解析xml文件
    		//parse(文件对象(或流),自定义事件处理器)
    //		saxParser.parse(new FileInputStream(path), dh);
    		saxParser.parse(new File(path),new MyHandler());
    	}

import org.xml.sax.Attributes;
    import org.xml.sax.SAXException;
    import org.xml.sax.helpers.DefaultHandler;
    
    public class MyHandler extends DefaultHandler {
    
    	/**
    	 * 开始读取文档
    	 */
    	@Override
    	public void startDocument() throws SAXException {
    //		System.out.println("开始读取文档：startDocument()");
    	}
    
    	/**
    	 * 文档读取结束
    	 */
    	@Override
    	public void endDocument() throws SAXException {
    //		System.out.println("文档读取结束：endDocument()");
    	}
    
    	/**
    	 * 开始读取元素时调用
    	 * @param uri
    	 * @param localName
    	 * @param qName
    	 * @throws SAXException
    	 */
    	@Override
    	public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
    //		System.out.println("开始读取元素：startElement()");
    //		System.out.println(uri);
    //		System.out.println(localName);
    //		System.out.println(qName);
    //		System.out.println(attributes.getIndex(qName));
    		//取属性
    		/*for (int i = 0; i < attributes.getLength(); i++) {
    			String qName2 = attributes.getQName(i);
    			String value = attributes.getValue(i);
    			System.out.println(qName2+"--"+value);
    		}*/
    		
    		System.out.print("<"+qName);
    		for (int i = 0; i < attributes.getLength(); i++) {
    			String qName2 = attributes.getQName(i);
    			String value = attributes.getValue(i);
    			System.out.print(" "+qName2+"=\""+value+"\"");
    		}
    		System.out.print(">");
    	}
    
    	/**
    	 * 结束读取元素
    	 */
    	@Override
    	public void endElement(String uri, String localName, String qName) throws SAXException {
    //		System.out.println("结束读取元素：endElement()");
    //		System.out.println(qName);
    		System.out.println("</"+qName+">");
    	}
    
    	/**
    	 * 读取到元素值时
    	 */
    	@Override
    	public void characters(char[] ch, int start, int length) throws SAXException {
    //		System.out.println("读取到元素值时：characters()");
    		for (int i = 0; i < ch.length; i++) {
    			//元素值：[start,start+length)
    			if(i>=start&&i<start+length) {
    				System.out.print(ch[i]);//结果：Tom20maleBob20male
    			}
    		}
    	}
    
    }

# 四、dom4j解析 #

/**
    	 * dom4j解析xml文件
    	 * 
    	 * @param path
    	 *            需要解析的xml文件
    	 * @throws Exception
    	 */
    	public static void dom4j(String path) throws Exception {
    		// System.out.println(path);
    		// 1.构建解析器
    		SAXReader sr = new SAXReader();
    		// 2.调用方法解析文件
    		Document document = sr.read(new File(path));
    		// 3.获取根节点
    		Element root = document.getRootElement();
    		System.out.println("<" + root.getName() + ">");
    		// 4.获取一级节点集合，一级节点下面包含很多二级节点
    		List<Element> elements = root.elements();
    		for (Element element : elements) {
    			System.out.print("\t" + "<" + element.getName() + " ");
    			// 获取一级节点属性
    			List<Attribute> attr = element.attributes();
    			for (Attribute attribute : attr) {
    				System.out.print(attribute.getName() + "=\"" + attribute.getText() + " ");
    			}
    			System.out.println(">");
    			// 获取二级节点
    			List<Element> e = element.elements();
    			for (Element e1 : e) {
    				System.out.println("\t\t" + "<" + e1.getName() + ">" + e1.getText() + "</" + e1.getName() + ">");
    			}
    			// 一级节点结束标签
    			System.out.println("\t" + "</" + element.getName() + ">");
    		}
    		System.out.println("</" + root.getName() + ">");
    	}

/**
    	 * dom4j写数据到xml文件
    	 * 
    	 * @param xmlPath
    	 *            xml文件路径
    	 * @throws Exception
    	 */
    	public static void dom4jWriter(String xmlPath) throws Exception {
    		// 1.创建一个document对象
    		Document document = DocumentHelper.createDocument();
    		// 2.创建根结点
    		Element root = document.addElement("employees");
    		// 3.创建一级节点
    		Element firstNode1 = root.addElement("employee");
    		Element firstNode2 = root.addElement("employee");
    
    		// 创建一级标签属性
    		firstNode1.setAttributeValue("status", "在职");
    		firstNode2.setAttributeValue("status", "离职");
    		// 4.创建二级节点
    		Element idNode1 = firstNode1.addElement("id");
    		Element nameNode1 = firstNode1.addElement("name");
    		Element ageNode1 = firstNode1.addElement("age");
    		Element depNameNode1 = firstNode1.addElement("depName");
    
    		Element idNode2 = firstNode2.addElement("id");
    		Element nameNode2 = firstNode2.addElement("name");
    		Element ageNode2 = firstNode2.addElement("age");
    		Element depNameNode2 = firstNode2.addElement("depName");
    
    		// 设置二级节点的值
    		idNode1.setText("A12");
    		nameNode1.setText("张三");
    		ageNode1.setText("18");
    		depNameNode1.setText("教学部");
    
    		idNode2.setText("A13");
    		nameNode2.setText("李四");
    		ageNode2.setText("23");
    		depNameNode2.setText("MIS部");
    
    		// 5.写到文件
    		// 格式化对象
    		OutputFormat format = OutputFormat.createPrettyPrint();
    
    		File file = new File(xmlPath);
    		if (!file.exists()) {
    			file.createNewFile();
    		}
    		// 格式化
    		// XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(file),format);
    		// 非格式化
    		XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(file));
    
    		xmlWriter.write(document);
    		xmlWriter.flush();
    		xmlWriter.close();
    
    	}