**xml
xml约束模式文档（作用：规定xml文件的语法）：
???DTD(.dtd) , XML?Schema(.xsd)
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?? 对比两者来看XML Schema的优势：
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xml解析方式：
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参考：http://blog.cnw.com.cn/?uid-72913-action-viewspace-itemid-144395
<?xml version="1.0" encoding="UTF-8"?> <employees> <employee> <name>ddviplinux</name> <sex>m</sex> <age>30</age> </employee> </employees>?
? ?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;/* 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）。
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());}}}?
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??? 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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import java.io.*;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;/** * * 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));}}?
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");}}
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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;iElement employee=(Element)employeeList.get(i); List employeeInfo=employee.getChildren(); for(int j=0;jSystem.out.println(((Element)employeeInfo.get(j)).getName()+":"+((Element)employeeInfo.get(j)).getValue()); } } } catch (JDOMException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
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xml名字空间：
?? 使用名字空间的原因：
?? 名字空间的声明：
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