Java解析XML的四種方法

簡介

XML現在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。


XML文件解析方法

XML在不同的語言裏解析方式都是一樣的,只不過實現的語法不同而已。基本的解析方式有兩種,一種叫SAX,另一種叫DOM。SAX是基於事件流的解析,DOM是基於XML文檔樹結構的解析。假設我們XML的內容和結構如下:

<?xml version="1.0" encoding="UTF-8"?> 
<employees> 
  <employee> 
    <name>ddviplinux</name> 
    <sex>m</sex> 
    <age>30</age> 
  </employee> 
</employees>

本文實現DOM與SAX的XML文檔生成與解析。 

首先定義一個操作XML文檔的接口XmlDocument 它定義了XML文檔的建立與解析的接口。

package com.alisoft.facepay.framework.bean;

/**
 * 
 * @author hongliang.dinghl 
 * 定義XML文檔建立與解析的接口
 */
public interface XmlDocument {
	/**
	 * 建立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,然後構建一個駐留內存的樹結構,然後代碼就可以使用 DOM 接口來操作這個樹結構。優點:整個文檔樹在內存中,便於操作;支持刪除、修改、重新排列等多種功能;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多次訪問這些數據;硬件資源充足(內存、CPU)。 

(1)DOM解析XML文檔所使用到的jar:dom.jar

(2)DOM解析與創建XML文檔示例代碼

package com.alisoft.facepay.framework.bean;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
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());
		}
	}
	
	//創建一個xml文件
	public void createXml(String fileName) {
		Element root = this.document.createElement("employees");  //創建一個xml文件根節點
		this.document.appendChild(root); //把根節點加到xml文檔結構下面
		Element employee = this.document.createElement("employee"); //創過employee節點
		Element name = this.document.createElement("name"); //創建name節點
		name.appendChild(this.document.createTextNode("丁宏亮")); //創建一個內容,並把內容加到name節點下面
		employee.appendChild(name);  //把name加到employee下面
		Element sex = this.document.createElement("sex"); //創建軍一個sex節點
		sex.appendChild(this.document.createTextNode("m")); //創建一個性別添加到性別節點下面
		employee.appendChild(sex); //把性別添加到,人員節點下面
		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()); 
		} 

	}

	//解釋一個XML文件
	public void parserXml(String fileName) {
		try {
			DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
			DocumentBuilder db = dbf.newDocumentBuilder();
			Document document = db.parse(fileName); // 讀取xml文件
			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。優點: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;事件過後,若沒保存數據,那麼數據就丟了;無狀態性;從事件中只能得到文本,但不知該文本屬於哪個元素;使用場合:Applet;只需XML文檔的少量內容,很少回頭訪問;機器內存少;

(1)SAX解析XML文檔所使用到的jar包:sax.jar

(2)SAX關健類的,類結構圖

(3)SAX文檔解釋示例代碼

package com.alisoft.facepay.framework.bean;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;

public class XMLParser {
	protected PrintStream output = new PrintStream(new BufferedOutputStream(
			new FileOutputStream(java.io.FileDescriptor.out), 128), true);
	// handler error info.
	protected PrintStream error = new PrintStream(new BufferedOutputStream(
			new FileOutputStream(java.io.FileDescriptor.err), 128), true);

	public void parserXMLFile(String fileName) throws SAXException, IOException {
		XMLReader reader = XMLReaderFactory.createXMLReader();
		reader.setContentHandler(new MyContentHandler());
		reader.setErrorHandler(new MyErrorHandler());
		InputSource source = new InputSource(new FileInputStream(new File(
				fileName)));
		reader.parse(source);
	}

	class MyErrorHandler implements ErrorHandler {

		public void error(SAXParseException exception) throws SAXException {

			error.println(exception.getMessage());
		}

		public void fatalError(SAXParseException exception) throws SAXException {

			error.println(exception.getMessage());
		}

		public void warning(SAXParseException exception) throws SAXException {
			output.println(exception.getMessage());

		}

	}

	class MyContentHandler implements ContentHandler {

		private StringBuffer buffer = new StringBuffer();
		private String key;

		public void characters(char[] ch, int start, int length)
				throws SAXException {
			buffer.append(ch, start, length); // 添加標記中間的內容

		}

		public void endDocument() throws SAXException {

		}

		public void endElement(String uri, String localName, String name)
				throws SAXException {
			if (key.equals(localName)) {
				output.print(buffer); // 輸出標記中間的內容
			}
			output.print("</" + localName + ">");
		}

		public void endPrefixMapping(String prefix) throws SAXException {
		}

		public void ignorableWhitespace(char[] ch, int start, int length)
				throws SAXException {
		}

		public void processingInstruction(String target, String data)
				throws SAXException {
		}

		public void setDocumentLocator(Locator locator) {
		}

		public void skippedEntity(String name) throws SAXException {
		}

		public void startDocument() throws SAXException // XML文檔開始讀取時調用
		{
			output.println("<xml version=\"1.0\" encoding=\"utf-8\"?>");
		}

		public void startElement(String uri, String localName, String name,
				Attributes atts) throws SAXException // 獲取標記開始信息
		{
			// uri is identifier of namespace
			// name-->prefix:localName

			buffer.delete(0, buffer.length());
			key = localName;

			output.print("<" + localName);
			for (int i = 0; i < atts.getLength(); i++) {
				String attrName = atts.getLocalName(i);
				String attrValue = atts.getValue(i);
				output.print(" " + attrName + "=" + attrValue);
			}
			output.print(">" + "\r");
		}

		public void startPrefixMapping(String prefix, String uri)
				throws SAXException {
		}
	}

	public static void main(String[] args) throws Exception, IOException {
		XMLParser parser = new XMLParser();
		parser.parserXMLFile("D:/testSpace/testPrj/src/xmlPackage/MyXml.xml"); // 解釋XML文件
	}
}

(4)SAX生成XML文檔示例代碼(生成XML)

package com.alisoft.facepay.framework.bean;

import java.io.FileOutputStream;
import java.io.StringWriter;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;

public class XMLHandler {
	public String createXMLFile() {
		String xmlStr = null;
		try {
			Result resultXml = new StreamResult(new FileOutputStream(
					"E://cities.xml"));
			StringWriter writerStr = new StringWriter();
			SAXTransformerFactory sff = (SAXTransformerFactory) SAXTransformerFactory
					.newInstance();
			TransformerHandler th = sff.newTransformerHandler();
			Transformer transformer = th.getTransformer();
			transformer.setOutputProperty(OutputKeys.INDENT, "yes");
			transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
			th.setResult(resultXml);
			th.startDocument();
			String four = "\n    ";
			String eight = "\n        ";
			AttributesImpl attr = new AttributesImpl();
			th.startElement("", "", "country", attr);
			th.characters(four.toCharArray(), 0, four.length());

			th.startElement("", "", "china", attr);

			th.characters(eight.toCharArray(), 0, eight.length());

			th.startElement("", "", "city", attr);
			String bj = "Beijing";
			th.characters(bj.toCharArray(), 0, bj.length());
			th.endElement("", "", "city");

			th.characters(eight.toCharArray(), 0, eight.length());

			th.startElement("", "", "city", attr);
			String sh = "Shanghai";
			th.characters(sh.toCharArray(), 0, sh.length());
			th.endElement("", "", "city");

			th.characters(four.toCharArray(), 0, four.length());

			th.endElement("", "", "china");
			th.endElement("", "", "country");
			th.endDocument();
			xmlStr = writerStr.getBuffer().toString();
		} catch (TransformerConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return xmlStr;
	}

	public static void main(String args[]) {
		XMLHandler xh = new XMLHandler();
		xh.createXMLFile();
	}
}

生成的XML文檔:

<?xml version="1.0" encoding="UTF-8" ?>
<country>
	<china>
		<city>Beijing</city>
		<city>Shanghai</city>
	</china>
</country>

3.DOM4J生成和解析XML文檔

DOM4J 是一個非常非常優秀的Java XML API,具有性能優異、功能強大和極端易用使用的特點,同時它也是一個開放源代碼的軟件。如今你可以看到越來越多的 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。

(1)Dom4j解析XML文檔所使用到的jar包:dom4j.jar

(2)Dom4j文檔解釋示例代碼

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 {

	// Dom4j創建Xml文檔
	public void createXml(String fileName) {
		Document document = DocumentHelper.createDocument(); // 創建一個文檔對象
		Element employees = document.addElement("employees"); // 在根節點添加元素
		Element employee = employees.addElement("employee"); // 在employees下添加子節點
		Element name = employee.addElement("name"); // 在employee下添加子節點
		name.setText("ddvip"); // 給name節點添加內容
		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());
		}

	}

	// Dom4j解釋Xml文檔
	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();) { // 遍例節點
					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

爲減少DOM、SAX的編碼量,出現了JDOM;優點:20-80原則,極大減少了代碼量。使用場合:要實現的功能簡單,如解析、創建等,但在底層,JDOM還是使用SAX(最常用)、DOM、Xanan文檔。

(1)JDOM解析XML文檔所使用到的jar包jdom.jar
(2)JDOM文檔解釋示例代碼

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();
			// 獲取employee節點
			for (int i = 0; i < employeeList.size(); i++) {
				Element employee = (Element) employeeList.get(i);
				List employeeInfo = employee.getChildren();
				// 獲取employee節點下面的所有子節點
				for(int j = 0; j < employeeInfo.size(); j++) {
					Element info = (Element)employeeInfo.get(j);
					System.out.println(info.getName() + ":" + info.getValue());
				}
			}
		} catch (JDOMException  e) {
			System.out.println(e.getMessage());
		} catch (IOException e) {
			System.out.println(e.getMessage());
		}
	}
}


轉載自此處


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