XML编程:利用java程序去增删改查(CRUD)xml中的数据解析思想:dom解析sax解析基于这两种解析思想市面上就有了很多的解析apisun jaxp既有dom方式也有sax方式,并且这套解析api已经加入到j2se的规范中,意味这不需要导入任何第三方开发包就可以直接使用这种解析方式.但是这种解析方式效率低下,没什么人用.dom4j 可以使用dom方式高效的解析xml.pull!!dom4j
导入开发包,通常只需要导入核心包就可以了,如果在使用的过程中提示少什么包到lib目录下在导入缺少的包即可
解析的xml文件：
<?xml version="1.0" encoding="UTF-8"?><书架> <书 出版社="北京出版社"><书名>Java就业培训教程</书名><作者>张孝祥</作者><售价>50.00元</售价><特价>20.0元</特价> </书><书><书名>JavaScript网页开发</书名><作者>张孝祥</作者><售价>40.00元</售价> </书> </书架>SAX解析方式：package sax;import javax.xml.parsers.ParserConfigurationException;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import org.xml.sax.Attributes;import org.xml.sax.ContentHandler;import org.xml.sax.Locator;import org.xml.sax.SAXException;import org.xml.sax.XMLReader;import org.xml.sax.helpers.DefaultHandler;public class SaxDemo1 {public static void main(String[] args) throws Exception {//解析器工厂SAXParserFactory factory=SAXParserFactory.newInstance();//sax解析器SAXParser parser = factory.newSAXParser();//获取读取器XMLReader reader = parser.getXMLReader();//注册事件reader.setContentHandler(new MyContentHander2());//解析xml文档reader.parse("book.xml");}}//读取第二本书的价格class MyContentHander2 extends DefaultHandler{private String eleName="";private int count=0;@Overridepublic void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {super.startElement(uri, localName, qName, attributes);this.eleName=qName;}@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {super.endElement(uri, localName, qName);eleName="";}@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {super.characters(ch, start, length);if("书名".equals(eleName)&&++count==2){System.out.println(new String(ch,start,length));}}}class MyContentHander implements ContentHandler{@Overridepublic void setDocumentLocator(Locator locator) {// TODO Auto-generated method stub}@Overridepublic void startDocument() throws SAXException {// TODO Auto-generated method stubSystem.out.println("开始读取文档….");}@Overridepublic void endDocument() throws SAXException {// TODO Auto-generated method stubSystem.out.println("结束读取文档….");}@Overridepublic void startPrefixMapping(String prefix, String uri)throws SAXException {// TODO Auto-generated method stub}@Overridepublic void endPrefixMapping(String prefix) throws SAXException {// TODO Auto-generated method stub}@Overridepublic void startElement(String uri, String localName, String qName,Attributes atts) throws SAXException {// TODO Auto-generated method stubSystem.out.println("发现开始标签,"+qName);}@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {// TODO Auto-generated method stubSystem.out.println("结束考试标签,"+qName);}@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {// TODO Auto-generated method stubSystem.out.println(new String(ch, start, length));}@Overridepublic void ignorableWhitespace(char[] ch, int start, int length)throws SAXException {// TODO Auto-generated method stub}@Overridepublic void processingInstruction(String target, String data)throws SAXException {// TODO Auto-generated method stub}@Overridepublic void skippedEntity(String name) throws SAXException {// TODO Auto-generated method stub}}dom4j解析：package dom4j;import java.io.FileOutputStream;import java.util.List;import org.dom4j.Attribute;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.DocumentHelper;import org.dom4j.Element;import org.dom4j.io.OutputFormat;import org.dom4j.io.SAXReader;import org.dom4j.io.XMLWriter;import org.junit.Test;public class Dom4jDemo {@Testpublic void attr() throws Exception{SAXReader reader=new SAXReader();Document doc = reader.read("book.xml");Element rootElement = doc.getRootElement();Element attribute = rootElement.element("书").addAttribute("出版社", "北京出版社");XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());writer.write(doc);writer.close();}@Testpublic void add()throws Exception{SAXReader reader=new SAXReader();Document doc = reader.read("book.xml");Element rootElement = doc.getRootElement();//凭空创建Element Telement = DocumentHelper.createElement("特价");Telement.setText("20.0元");//挂载rootElement.element("书").add(Telement);XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());writer.write(doc);writer.close();}@Testpublic void delete()throws Exception{SAXReader reader=new SAXReader();Document doc = reader.read("book.xml");Element rootElement = doc.getRootElement();Element element = rootElement.element("书").element("特价");element.getParent().remove(element);XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());writer.write(doc);writer.close();}@Testpublic void update() throws Exception{//dom4j解析器SAXReader reader=new SAXReader();//得到documentDocument doc = reader.read("book.xml");//得到根元素Element rootElement = doc.getRootElement();List<Element> elements = rootElement.elements();Element element = elements.get(0);element.element("售价").setText("50.00元");XMLWriter writer = new XMLWriter(new FileOutputStream("book.xml"),OutputFormat.createPrettyPrint());writer.write(doc);writer.close();}@Testpublic void find() throws Exception{//dom4j解析器SAXReader reader=new SAXReader();//得到documentDocument doc = reader.read("book.xml");//得到根元素Element rootElement = doc.getRootElement();List<Element> elements = rootElement.elements();Element element = elements.get(1);System.out.println(element.element("书名").getText());}}
，值不值得，真是不足为外人道，自己心里有数就行。
