【转】JAVA解析XML的四种方法

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XML Java Bean J#数据结构

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:

PS:在使用这些类库的时候别忘了引入他们各自的jar包，并放到lib目录下,DOM和SAX解析不需要额外加入jar包了,在jre\lib\rt.jar中已经包含了2种方式的类库

<?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；

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。(目前最新dom4j包下载地址:http://nchc.dl.sourceforge.net/sourceforge/dom4j/dom4j-1.6.1.zip解开后有两个包,仅操作XML文档的话把dom4j-1.6.1.jar加入工程就可以了,如果需要使用XPath的话还需要加入包jaxen-1.1-beta-7.jar.
)

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();   
        }    
  
    }   
}

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