JAVA 解析 XML 的 四种技术

1
	解析XML
	XML现在已经成为一种通用的数据交换格式,平台的无关性使得很多场合都需要用到XML。本文将详细介绍用Java解析
	XML的四种方法。
	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

	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(); 
			} c
			atch (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。

	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<employeeList.size();i++)
				{
					Element employee=(Element)employeeList.get(i); 
					List employeeInfo=employee.getChildren(); 
					for(int j=0;j<employeeList.size();i++)
					{
						System.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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