使用java解析XML
Java本身提供了三种API进行XML文本的解析。
1.DOM：DOM方式解析XML文本时，先分析整个XML，形成XML的DOM树，然后节点列表的方式遍历它。
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package xmlHandler;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.xpath.XPath;import javax.xml.xpath.XPathExpressionException;import javax.xml.xpath.XPathFactory;import org.w3c.dom.Document;import org.w3c.dom.Element;import org.w3c.dom.Node;import org.w3c.dom.NodeList;import org.w3c.dom.Text;import org.xml.sax.SAXException;public class DOMParserXml {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stub DOMParserXml domparser=new DOMParserXml(); domparser.domParserForXML(System.getProperty("user.dir")+"/person.xml"); domparser.XPathGetValue(System.getProperty("user.dir")+"/person.xml");}// DOM解析器生成tree，解析过程也必须严格按照tree结构写成循环解析public void domParserForXML(String xmlPath) {Person person = new Person();// 用于存放解析出的值DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();// 创建XML的DOM工厂try {DocumentBuilder builder = factory.newDocumentBuilder();File xmlFile = new File(xmlPath);// 可以用InputStream、URL、File来设置XML来源Document doc = builder.parse(xmlFile);// 读入文档,这是一个接口Element root = doc.getDocumentElement();// 获取根节点System.out.println("根节点名称：" + root.getTagName());NodeList children = root.getChildNodes();// 这里的child可以使文本、子元素、其他节点for (int i = 0; i < children.getLength(); i++) {Node child = children.item(i);//使用语句factory.setIgnoringElementContentWhitespace(true);//过滤空白字符，就不需要判断类型了。if (child instanceof Element) {// 解析器将标签之间的空格也认为是子元素，用instanceof过滤它们Element childElement = (Element) child;System.out.print("\t子节点名称" + childElement.getTagName());System.out.println("\t属性值："+ childElement.getAttribute("sex"));//可以通过getAttributes方法获取所有属性值的键值对。person.setSex(childElement.getAttribute("sex"));NodeList grandsons = childElement.getChildNodes();for (int j = 0; j < grandsons.getLength(); j++) {Node grandson = grandsons.item(j);if (grandson instanceof Element) {Element grandElement = (Element) grandson;System.out.print("\t\t孙节点名称:"+ grandElement.getTagName());Text textNode = (Text) grandElement.getFirstChild();System.out.println("\t孙节点文本值:"+ textNode.getData().trim());if (grandElement.getTagName().equals("name")) {person.setName(textNode.getData().trim());}if (grandElement.getTagName().equals("description")) {person.setDescription(textNode.getData().trim());}}}}}} catch (ParserConfigurationException e) {// TODO Auto-generated catch blocke.printStackTrace();}// 创建解析器catch (SAXException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("解析结果：：：" + person.toString());}public void XPathGetValue(String xmlFilePath){DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();// 创建XML的DOM工厂try {DocumentBuilder builder = factory.newDocumentBuilder();File file=new File(xmlFilePath);Document doc=builder.parse(file);//通过XPath表达式快速访问XML文件的节点及其文本值XPathFactory xpathFactory=XPathFactory.newInstance();XPath xpath=xpathFactory.newXPath();System.out.println("==============使用XPath快速访问XML节点值：");String query="/persons/person/name";System.out.println(xpath.evaluate(query, doc));} catch (ParserConfigurationException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (SAXException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (XPathExpressionException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}?2.SAXParser使用事件流驱动的方式进行XML文本的解析。
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package xmlHandler;import java.io.File;import java.io.IOException;import javax.xml.parsers.ParserConfigurationException;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;public class SAXParserXML {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubSAXParserFactory factory = SAXParserFactory.newInstance();try {SAXParser parser = factory.newSAXParser();File file = new File(System.getProperty("user.dir") + "/person.xml");parser.parse(file, new PersonXMLHandler());// 此处的file可以使文件、输入流、或URL字符串} catch (ParserConfigurationException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (SAXException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}class PersonXMLHandler extends DefaultHandler {Person person;String temp = "";String currenttag = null;@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {// TODO Auto-generated method stubif (currenttag != null) {String value = new String(ch, start, length);if (currenttag.equals("name")) {person.setName(value);}if (currenttag.equals("description")) {temp += value;// 处理长文本}}}@Overridepublic void endDocument() throws SAXException {// TODO Auto-generated method stubsuper.endDocument();}@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {// TODO Auto-generated method stubcurrenttag=null;if (qName.endsWith("description")) {person.setDescription(temp);temp = "";}if (qName.endsWith("person"))System.out.println("当前解析出的结果：" + person.toString());}@Overridepublic void startDocument() throws SAXException {// TODO Auto-generated method stubsuper.startDocument();}@Overridepublic void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {// TODO Auto-generated method stubif (qName.equals("person")) {person = new Person();person.setSex(attributes.getValue("sex"));}currenttag = qName;}}?3，StAX同样也是事件流驱动的解析器，只是不再进行startElement、characters的区分。
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package xmlHandler;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import javax.xml.stream.XMLInputFactory;import javax.xml.stream.XMLStreamConstants;import javax.xml.stream.XMLStreamException;import javax.xml.stream.XMLStreamReader;public class StAXParserXML {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stub StAXParserXML parser=new StAXParserXML(); parser.StAXParser(System.getProperty("user.dir") + "/person.xml");}// StAXParser 是一种“pull parser”，允许通过循环来迭代访问所有事件public void StAXParser(String xmlPath) {XMLInputFactory factory = XMLInputFactory.newInstance();Person person=new Person();File file = new File(xmlPath);try {//参数必须是InputStream类型，可以是File的包装器、URL打开的InputStreamXMLStreamReader parser = factory.createXMLStreamReader(new FileInputStream(file));// parser遍历xml文档时产生一系列事件while (parser.hasNext()) {int event = parser.next();// 获取当前eventif (event == XMLStreamConstants.START_ELEMENT) {//如果是elementif (parser.getLocalName().equals("person")) {//判断标签值person.setSex(parser.getAttributeValue(0));//获取属性值}if(parser.getLocalName().equals("name")){person.setName(parser.getElementText());//获取元素文本}if(parser.getLocalName().equals("description")){person.setDescription(parser.getElementText());}}}} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (XMLStreamException e) {// TODO Auto-generated catch blocke.printStackTrace();}// 这里的参数只能是InputStreamSystem.out.println(person.toString());}}?具体的参见源代码就行了