XML的4中解析方式

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),具体可参阅w3c官方网站文档http://www.w3.org获取更多信息。

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:

<?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。

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

*/

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）。

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());

}

}

}

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；

Java代码

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));  

}  

} 

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));

}

}

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。

Java代码

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");  

}  

}  

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。

  

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();  

}   

}  

}