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XML现在已经成为一种通用的数据交换格式,它的平台无关性,语言无关性,系统无关性,给数据集成与交互带来了极大的方便。对于XML本身的语法知识与技术细节,需要阅读相关的技术文献,这里面包括的内容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations),

XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已。基本的解析方式有两种,一种叫SAX,另一种叫DOM。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析。假设我们XML的内容和结构如下:
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 ddviplinux m 30 ddviplinux m 30 
本文使用JAVA语言来实现DOM与SAX的XML文档生成与解析。
首先定义一个操作XML文档的接口XmlDocument 它定义了XML文档的建立与解析的接口。
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 - package com.alisoft.facepay.framework.bean;
 - /**
 - *
 - * @author hongliang.dinghl
 - * 定义XML文档建立与解析的接口
 - */
 - public interface XmlDocument {
 - /**
 - * 建立XML文档
 - * @param fileName 文件全路径名称
 - */
 - public void createXml(String fileName);
 - /**
 - * 解析XML文档
 - * @param fileName 文件全路径名称
 - */
 - 18.public void parserXml(String fileName);
 - 19.}
 - 20.package com.alisoft.facepay.framework.bean;
 - 21./**
 - 22. *
 - 23. * @author hongliang.dinghl
 - * 定义XML文档建立与解析的接口
 - */
 - public interface XmlDocument {
 - /**
 - * 建立XML文档
 - * @param fileName 文件全路径名称
 - */
 - public void createXml(String fileName);
 - /**
 - * 解析XML文档
 - * @param fileName 文件全路径名称
 - */
 - public void parserXml(String fileName);
 - }
 
1. DOM生成和解析XML文档
为 XML 文档的已解析版本定义了一组接口。解析器读入整个文档,然后构建一个驻留内存的树结构,然后代码就可以使用 DOM 接口来操作这个树结构。优点:整个文档树在内存中,便于操作;支持删除、修改、重新排列等多种功能;缺点:将整个文档调入内存(包括无用的节点),浪费时间和空间;使用场合:一旦解析了文档还需多次访问这些数据;硬件资源充足(内存、CPU)。
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 - package com.alisoft.facepay.framework.bean;
 - import java.io.FileInputStream;
 - import java.io.FileNotFoundException;
 - import java.io.FileOutputStream;
 - import java.io.IOException;
 - import java.io.InputStream;
 - import java.io.PrintWriter;
 - import javax.xml.parsers.DocumentBuilder;
 - import javax.xml.parsers.DocumentBuilderFactory;
 - import javax.xml.parsers.ParserConfigurationException;
 - import javax.xml.transform.OutputKeys;
 - import javax.xml.transform.Transformer;
 - import javax.xml.transform.TransformerConfigurationException;
 - import javax.xml.transform.TransformerException;
 - import javax.xml.transform.TransformerFactory;
 - import javax.xml.transform.dom.DOMSource;
 - import javax.xml.transform.stream.StreamResult;
 - import org.w3c.dom.Document;
 - import org.w3c.dom.Element;
 - import org.w3c.dom.Node;
 - import org.w3c.dom.NodeList;
 - import org.xml.sax.SAXException;
 - /**
 - * @author hongliang.dinghl
 - * DOM生成与解析XML文档
 - */
 - public class DomDemo implements XmlDocument {
 - private Document document;
 - private String fileName;
 - public void init() {
 - try {
 - DocumentBuilderFactory factory = DocumentBuilderFactory
 - .newInstance();
 - DocumentBuilder builder = factory.newDocumentBuilder();
 - this.document = builder.newDocument();
 - } catch (ParserConfigurationException e) {
 - System.out.println(e.getMessage());
 - }
 - }
 - public void createXml(String fileName) {
 - Element root = this.document.createElement(“employees”);
 - this.document.appendChild(root);
 - Element employee = this.document.createElement(“employee”);
 - Element name = this.document.createElement(“name”);
 - name.appendChild(this.document.createTextNode(“丁宏亮“));
 - employee.appendChild(name);
 - Element sex = this.document.createElement(“sex”);
 - sex.appendChild(this.document.createTextNode(“m”));
 - employee.appendChild(sex);
 - Element age = this.document.createElement(“age”);
 - age.appendChild(this.document.createTextNode(“30″));
 - employee.appendChild(age);
 - root.appendChild(employee);
 - TransformerFactory tf = TransformerFactory.newInstance();
 - try {
 - Transformer transformer = tf.newTransformer();
 - DOMSource source = new DOMSource(document);
 - transformer.setOutputProperty(OutputKeys.ENCODING, “gb2312″);
 - transformer.setOutputProperty(OutputKeys.INDENT, “yes”);
 - PrintWriter pw = new PrintWriter(new FileOutputStream(fileName));
 - StreamResult result = new StreamResult(pw);
 - transformer.transform(source, result);
 - System.out.println(“生成XML文件成功!”);
 - } catch (TransformerConfigurationException e) {
 - System.out.println(e.getMessage());
 - } catch (IllegalArgumentException e) {
 - System.out.println(e.getMessage());
 - } catch (FileNotFoundException e) {
 - System.out.println(e.getMessage());
 - } catch (TransformerException e) {
 - System.out.println(e.getMessage());
 - }
 - }
 - public void parserXml(String fileName) {
 - try {
 - DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
 - DocumentBuilder db = dbf.newDocumentBuilder();
 - Document document = db.parse(fileName);
 - NodeList employees = document.getChildNodes();
 - for (int i = 0; i < employees.getLength(); i++) {
 - Node employee = employees.item(i);
 - NodeList employeeInfo = employee.getChildNodes();
 - for (int j = 0; j < employeeInfo.getLength(); j++) {
 - Node node = employeeInfo.item(j);
 - NodeList employeeMeta = node.getChildNodes();
 - for (int k = 0; k < employeeMeta.getLength(); k++) {
 - System.out.println(employeeMeta.item(k).getNodeName()
 - + “:” + employeeMeta.item(k).getTextContent());
 - }
 - }
 - }
 - System.out.println(“解析完毕“);
 - } catch (FileNotFoundException e) {
 - System.out.println(e.getMessage());
 - } catch (ParserConfigurationException e) {
 - System.out.println(e.getMessage());
 - } catch (SAXException e) {
 - System.out.println(e.getMessage());
 - } catch (IOException e) {
 - System.out.println(e.getMessage());
 - }
 - }
 - }
 
#p#
2. SAX生成和解析XML文档
为解决DOM的问题,出现了SAX。SAX ,事件驱动。当解析器发现元素开始、元素结束、文本、文档的开始或结束等时,发送事件,程序员编写响应这些事件的代码,保存数据。优点:不用事先调入整个文档,占用资源少;SAX解析器代码比DOM解析器代码小,适于Applet,下载。缺点:不是持久的;事件过后,若没保存数据,那么数据就丢了;无状态性;从事件中只能得到文本,但不知该文本属于哪个元素;使用场合:Applet;只需XML文档的少量内容,很少回头访问;机器内存少;
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 - package com.alisoft.facepay.framework.bean;
 - import java.io.FileInputStream;
 - import java.io.FileNotFoundException;
 - import java.io.IOException;
 - import java.io.InputStream;
 - 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;
 - /**
 - * @author hongliang.dinghl
 - * SAX文档解析
 - */
 - public class SaxDemo implements XmlDocument {
 - public void createXml(String fileName) {
 - System.out.println(“<<”+filename+“>>”);
 - }
 - public void parserXml(String fileName) {
 - SAXParserFactory saxfac = SAXParserFactory.newInstance();
 - try {
 - SAXParser saxparser = saxfac.newSAXParser();
 - InputStream is = new FileInputStream(fileName);
 - saxparser.parse(is, new MySAXHandler());
 - } catch (ParserConfigurationException e) {
 - e.printStackTrace();
 - } catch (SAXException e) {
 - e.printStackTrace();
 - } catch (FileNotFoundException e) {
 - e.printStackTrace();
 - } catch (IOException e) {
 - e.printStackTrace();
 - }
 - }
 - }
 - class MySAXHandler extends DefaultHandler {
 - boolean hasAttribute = false;
 - Attributes attributes = null;
 - public void startDocument() throws SAXException {
 - System.out.println(“文档开始打印了“);
 - }
 - public void endDocument() throws SAXException {
 - System.out.println(“文档打印结束了“);
 - }
 - public void startElement(String uri, String localName, String qName,
 - Attributes attributes) throws SAXException {
 - if (qName.equals(“employees”)) {
 - return;
 - }
 - if (qName.equals(“employee”)) {
 - System.out.println(qName);
 - }
 - if (attributes.getLength() > 0) {
 - this.attributes = attributes;
 - this.hasAttribute = true;
 - }
 - }
 - public void endElement(String uri, String localName, String qName)
 - throws SAXException {
 - if (hasAttribute && (attributes != null)) {
 - for (int i = 0; i < attributes.getLength(); i++) {
 - System.out.println(attributes.getQName(0)
 - + attributes.getValue(0));
 - }
 - }
 - }
 - public void characters(char[] ch, int start, int length)
 - throws SAXException {
 - System.out.println(new String(ch, start, length));
 - }
 - }
 
#p#
3. DOM4J生成和解析XML文档
DOM4J 是一个非常非常优秀的Java XML API,具有性能优异、功能强大和极端易用使用的特点,同时它也是一个开放源代码的软件。如今你可以看到越来越多的 Java 软件都在使用 DOM4J 来读写 XML,特别值得一提的是连 Sun 的 JAXM 也在用 DOM4J。
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 - package com.alisoft.facepay.framework.bean;
 - import java.io.File;
 - import java.io.FileWriter;
 - import java.io.IOException;
 - import java.io.Writer;
 - import java.util.Iterator;
 - import org.dom4j.Document;
 - import org.dom4j.DocumentException;
 - import org.dom4j.DocumentHelper;
 - import org.dom4j.Element;
 - import org.dom4j.io.SAXReader;
 - import org.dom4j.io.XMLWriter;
 - /**
 - * @author hongliang.dinghl
 - * Dom4j 生成XML文档与解析XML文档
 - */
 - public class Dom4jDemo implements XmlDocument {
 - public void createXml(String fileName) {
 - Document document = DocumentHelper.createDocument();
 - Element employees=document.addElement(“employees”);
 - Element employee=employees.addElement(“employee”);
 - Element name= employee.addElement(“name”);
 - name.setText(“ddvip”);
 - Element sex=employee.addElement(“sex”);
 - sex.setText(“m”);
 - Element age=employee.addElement(“age”);
 - age.setText(“29″);
 - try {
 - Writer fileWriter=new FileWriter(fileName);
 - XMLWriter xmlWriter=new XMLWriter(fileWriter);
 - xmlWriter.write(document);
 - xmlWriter.close();
 - } catch (IOException e) {
 - System.out.println(e.getMessage());
 - }
 - }
 - public void parserXml(String fileName) {
 - File inputXml=new File(fileName);
 - SAXReader saxReader = new SAXReader();
 - try {
 - Document document = saxReader.read(inputXml);
 - Element employees=document.getRootElement();
 - for(Iterator i = employees.elementIterator(); i.hasNext();){
 - Element employee = (Element) i.next();
 - for(Iterator j = employee.elementIterator(); j.hasNext();){
 - Element node=(Element) j.next();
 - System.out.println(node.getName()+“:”+node.getText());
 - }
 - }
 - } catch (DocumentException e) {
 - System.out.println(e.getMessage());
 - }
 - System.out.println(“dom4j parserXml”);
 - }
 - }
 
#p#
4. JDOM生成和解析XML
为减少DOM、SAX的编码量,出现了JDOM;优点:20-80原则,极大减少了代码量。使用场合:要实现的功能简单,如解析、创建等,但在底层,JDOM还是使用SAX(最常用)、DOM、Xanan文档。
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 - package com.alisoft.facepay.framework.bean;
 - import java.io.FileNotFoundException;
 - import java.io.FileOutputStream;
 - import java.io.IOException;
 - import java.util.List;
 - import org.jdom.Document;
 - import org.jdom.Element;
 - import org.jdom.JDOMException;
 - import org.jdom.input.SAXBuilder;
 - import org.jdom.output.XMLOutputter;
 - /**
 - * @author hongliang.dinghl
 - * JDOM 生成与解析XML文档
 - */
 - public class JDomDemo implements XmlDocument {
 - public void createXml(String fileName) {
 - Document document;
 - Element root;
 - root=new Element(“employees”);
 - document=new Document(root);
 - Element employee=new Element(“employee”);
 - root.addContent(employee);
 - Element name=new Element(“name”);
 - name.setText(“ddvip”);
 - employee.addContent(name);
 - Element sex=new Element(“sex”);
 - sex.setText(“m”);
 - employee.addContent(sex);
 - Element age=new Element(“age”);
 - age.setText(“23″);
 - employee.addContent(age);
 - XMLOutputter XMLOut = new XMLOutputter();
 - try {
 - XMLOut.output(document, new FileOutputStream(fileName));
 - } catch (FileNotFoundException e) {
 - e.printStackTrace();
 - } catch (IOException e) {
 - e.printStackTrace();
 - }
 - }
 - public void parserXml(String fileName) {
 - SAXBuilder builder=new SAXBuilder(false);
 - try {
 - Document document=builder.build(fileName);
 - Element employees=document.getRootElement();
 - List employeeList=employees.getChildren(“employee”);
 - for(int i=0;i
 - Element employee=(Element)employeeList.get(i);
 - List employeeInfo=employee.getChildren();
 - for(int j=0;j
 - System.out.println(((Element)employeeInfo.get(j)).getName()+“:”+
 - ((Element)employeeInfo.get(j)).getValue());
 - }
 - }
 - } catch (JDOMException e) {
 - e.printStackTrace();
 - } catch (IOException e) {
 - e.printStackTrace();
 - }
 - }
 - }
 
希望对你有帮助。