详解Java解析XML的四种方法

转载：http://developer.51cto.com/art/200903/117512.htm

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;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();   

}    



}   

}