詳解Java解析XML的四種方法

作者：cnlw1985 2009-03-31 13:12:30

XML現(xiàn)在已經(jīng)成為一種通用的數(shù)據(jù)交換格式,平臺(tái)的無(wú)關(guān)性使得很多場(chǎng)合都需要用到XML。本文將詳細(xì)介紹用Java解析XML的四種方法。

XML現(xiàn)在已經(jīng)成為一種通用的數(shù)據(jù)交換格式,它的平臺(tái)無(wú)關(guān)性,語(yǔ)言無(wú)關(guān)性,系統(tǒng)無(wú)關(guān)性,給數(shù)據(jù)集成與交互帶來(lái)了極大的方便。對(duì)于XML本身的語(yǔ)法知識(shí)與技術(shù)細(xì)節(jié),需要閱讀相關(guān)的技術(shù)文獻(xiàn),這里面包括的內(nèi)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(wǎng)站文檔http://www.w3.org獲取更多信息。

XML在不同的語(yǔ)言里解析方式都是一樣的,只不過(guò)實(shí)現(xiàn)的語(yǔ)法不同而已?；镜慕馕龇绞接袃煞N,一種叫SAX，另一種叫DOM。SAX是基于事件流的解析,DOM是基于XML文檔樹結(jié)構(gòu)的解析。假設(shè)我們XML的內(nèi)容和結(jié)構(gòu)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語(yǔ)言來(lái)實(shí)現(xiàn)DOM與SAX的XML文檔生成與解析。
首先定義一個(gè)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

為 XML 文檔的已解析版本定義了一組接口。解析器讀入整個(gè)文檔，然后構(gòu)建一個(gè)駐留內(nèi)存的樹結(jié)構(gòu)，然后代碼就可以使用 DOM 接口來(lái)操作這個(gè)樹結(jié)構(gòu)。優(yōu)點(diǎn)：整個(gè)文檔樹在內(nèi)存中，便于操作；支持刪除、修改、重新排列等多種功能；缺點(diǎn)：將整個(gè)文檔調(diào)入內(nèi)存（包括無(wú)用的節(jié)點(diǎn)），浪費(fèi)時(shí)間和空間；使用場(chǎng)合：一旦解析了文檔還需多次訪問這些數(shù)據(jù)；硬件資源充足（內(nèi)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

為解決DOM的問題，出現(xiàn)了SAX。SAX ，事件驅(qū)動(dòng)。當(dāng)解析器發(fā)現(xiàn)元素開始、元素結(jié)束、文本、文檔的開始或結(jié)束等時(shí)，發(fā)送事件，程序員編寫響應(yīng)這些事件的代碼，保存數(shù)據(jù)。優(yōu)點(diǎn)：不用事先調(diào)入整個(gè)文檔，占用資源少；SAX解析器代碼比DOM解析器代碼小，適于Applet，下載。缺點(diǎn)：不是持久的；事件過(guò)后，若沒保存數(shù)據(jù)，那么數(shù)據(jù)就丟了；無(wú)狀態(tài)性；從事件中只能得到文本，但不知該文本屬于哪個(gè)元素；使用場(chǎng)合：Applet;只需XML文檔的少量?jī)?nèi)容，很少回頭訪問；機(jī)器內(nèi)存少；

Java代碼

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();   
  
        } 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("文檔開始打印了");   
  
    }   
  
    public void endDocument() throws SAXException {   
  
        System.out.println("文檔打印結(jié)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));   
  
    }   
  
}  

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(); 

} 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("文檔開始打印了"); 

} 

public void endDocument() throws SAXException { 

System.out.println("文檔打印結(jié)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(gè)非常非常優(yōu)秀的Java XML API，具有性能優(yōu)異、功能強(qiáng)大和極端易用使用的特點(diǎn)，同時(shí)它也是一個(gè)開放源代碼的軟件。如今你可以看到越來(lái)越多的 Java 軟件都在使用 DOM4J 來(lái)讀寫 XML，特別值得一提的是連 Sun 的 JAXM 也在用 DOM4J。

Java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 {   
  
    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

為減少DOM、SAX的編碼量，出現(xiàn)了JDOM；優(yōu)點(diǎn)：20-80原則，極大減少了代碼量。使用場(chǎng)合：要實(shí)現(xiàn)的功能簡(jiǎn)單，如解析、創(chuàng)建等，但在底層，JDOM還是使用SAX（最常用）、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                Element employee=(Element)employeeList.get(i);   
                List employeeInfo=employee.getChildren();   
                for(int j=0;j                    System.out.println(((Element)employeeInfo.get(j)).getName()+":"+((Element)employeeInfo.get(j)).getValue());   
                       
                }   
            }   
        } catch (JDOMException e) {   
           
            e.printStackTrace();   
        } catch (IOException e) {   
           
            e.printStackTrace();   
        }    
  
    }   
}