JAVA解析XML的四种方法比较(2)

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；

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。

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<employeeInfo.size();j++){

              System.out.println(((Element)employeeInfo.get(j)).getName()+“:”+((Element)employeeInfo.get(j)).getValue());

                  

              }

           }

       } catch (JDOMException e) {

       

           e.printStackTrace();

       } catch (IOException e) {

       

           e.printStackTrace();

       } 

 

    }

}