JAVA 中的四種解析XML方式

時間 2019-11-07

標籤 java 四種解析 xml 方式欄目 Java 简体版

原文原文鏈接

解析XML
XML如今已經成爲一種通用的數據交換格式,平臺的無關性使得不少場合都須要用到XML。本文將詳細介紹用Java解析
XML的四種方法。
XML如今已經成爲一種通用的數據交換格式,它的平臺無關性,語言無關性,系統無關性,給數據集成與交互帶來了極大的
方便。對於XML自己的語法知識與技術細節,須要閱讀相關的技術文獻,這裏麪包括的內容有DOM(Document Object
Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible
Stylesheet Language Transformations),具體可參閱w3c官方網站文檔http://www.w3.org獲取更多信息。
XML在不一樣的語言裏解析方式都是同樣的,只不過實現的語法不一樣而已。基本的解析方式有兩種,一種叫SAX，
另外一種叫DOM。

SAX是基於事件流的解析,DOM 是基於XML文檔樹結構的解析。 java

假設咱們XML的內容和結構以下: 
	<?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語言來實現DOM與SAX的XML文檔生成與解析。 
	首先定義一個操做XML文檔的接口XmlDocument 它定義了XML文檔的創建與解析的接口。
	
	package com.alisoft.facepay.framework.bean; 
	/** 
	* 
	* @author hongliang.dinghl 
	* 定義XML文檔創建與解析的接口 
	*/ 
	public interface XmlDocument { 
	/** 
	* 創建XML文檔 
	* @param fileName 文件全路徑名稱 
	*/ 
	public void createXml(String fileName); 
	/** 
	* 解析XML文檔 
	* @param fileName 文件全路徑名稱 
	*/ 
	public void parserXml(String fileName); 
	}

1.DOM生成和解析XML文檔爲 XML 文檔的已解析版本定義了一組接口。
解析器讀入整個文檔，而後構建一個駐留內存的樹結構，而後代碼就可使用 DOM 接口來操做這個樹結構。
優勢：整個文檔樹在內存中，便於操做；支持刪除、修改、從新排列等多種功能；
缺點：將整個文檔調入內存（包括無用的節點），浪費時間和空間；
使用場合：一旦解析了文檔還需屢次
訪問這些數據；硬件資源充足（內存、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生成與解析XML文檔 
	*/ 
	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("解析完畢"); 
			} 
			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文檔爲解決DOM的問題，出現了SAX。SAX ，事件驅動。
當解析器發現元素開始、元素結束、文本、文檔的開始或結束等時，發送事件，程序員編寫響應這些事件的代碼，保存數據。
優勢：不用事先調入整個文檔，佔用資源少；SAX解析器代碼比DOM解析器代碼小，適於Applet，下載。
缺點：不是持久的；事件事後，若沒保存數據，那麼數據就丟了；無狀態性；從事件中只能獲得文本，但不知該文本屬於哪一個元素

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文檔解析 
	*/ 
	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("文檔開始打印了"); 
		} 
		
		public void endDocument() throws SAXException 
		{ 
			System.out.println("文檔打印結束了"); 
		} 
		
		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文檔
DOM4J 是一個很是很是優秀的Java XML API，具備性能優異、功能強大和極端易用使用的特色，同時它也是一個開放源代
碼的軟件。現在你能夠看到愈來愈多的 Java 軟件都在使用 DOM4J 來讀寫 XML，特別值得一提的是連 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文檔與解析XML文檔 
	*/ 
	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
爲減小DOM、SAX的編碼量，出現了JDOM；優勢：20-80原則，極大減小了代碼量。使用場合：要實現的功能簡單，如
解析、建立等，但在底層，JDOM仍是使用SAX（最經常使用）、DOM、Xanan文檔。

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 生成與解析XML文檔 
	*   
	*/ 
	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(); 
			} 
		} 
	}