Java解析XML的四种方法详解

XML现在已经成为一种通用的数据交换格式,它的平台无关性,语言无关性,系统无关性,给数据集成与交互带来了极大的方便。对于XML本身的语法知识与技术细节,需要阅读相关的技术文献,这里面包括的内容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations)。

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:

view source

print?

1<?xmlversion="1.0"encoding="UTF-8"?>  

2<employees>  

3    <employee>  

4        <name>ddviplinux</name>  

5        <sex>m</sex>  

6        <age>30</age>  

7    </employee>  

8</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。

view source

print?

01/**   

02 * 定义XML文档建立与解析的接口  

03 */  

04public interface XmlDocument {  　　

05    /**  　　 

06     * 建立XML文档  　　 

07     * @param fileName 文件全路径名称  　　 

08     */ 　　

09    public void createXml(String fileName);  　　

10    /**  　　 

11     * 解析XML文档  　　 

12     * @param fileName 文件全路径名称  　　 

13     */ 　　

14    public void parserXml(String fileName); 

15}

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）。

view source

print?

001package com.alisoft.facepay.framework.bean;

002  

003import java.io.FileInputStream;

004import java.io.FileNotFoundException;

005import java.io.FileOutputStream;

006import java.io.IOException;

007import java.io.InputStream;

008import java.io.PrintWriter;

009import javax.xml.parsers.DocumentBuilder;

010import javax.xml.parsers.DocumentBuilderFactory;

011import javax.xml.parsers.ParserConfigurationException;

012import javax.xml.transform.OutputKeys;

013import javax.xml.transform.Transformer;

014import javax.xml.transform.TransformerConfigurationException;

015import javax.xml.transform.TransformerException;

016import javax.xml.transform.TransformerFactory;

017import javax.xml.transform.dom.DOMSource;

018import javax.xml.transform.stream.StreamResult;

019import org.w3c.dom.Document;

020import org.w3c.dom.Element;

021import org.w3c.dom.Node;

022import org.w3c.dom.NodeList;

023import org.xml.sax.SAXException;

024  

025public class DomDemo implements XmlDocument {

026    private Document document;

027    private String fileName;

028  

029    public void init() {

030        try{

031            DocumentBuilderFactory factory = DocumentBuilderFactory

032                    .newInstance();

033            DocumentBuilder builder = factory.newDocumentBuilder();

034            this.document = builder.newDocument();

035        }catch (ParserConfigurationException e) {

036            System.out.println(e.getMessage());

037        }

038    }

039  

040    public void createXml(String fileName) {

041        Element root =this.document.createElement("employees");

042        this.document.appendChild(root);

043        Element employee =this.document.createElement("employee");

044        Element name =this.document.createElement("name");

045        name.appendChild(this.document.createTextNode("丁宏亮"));

046        employee.appendChild(name);

047        Element sex =this.document.createElement("sex");

048        sex.appendChild(this.document.createTextNode("m"));

049        employee.appendChild(sex);

050        Element age =this.document.createElement("age");

051        age.appendChild(this.document.createTextNode("30"));

052        employee.appendChild(age);

053        root.appendChild(employee);

054        TransformerFactory tf = TransformerFactory.newInstance();

055        try{

056            Transformer transformer = tf.newTransformer();

057            DOMSource source =new DOMSource(document);

058            transformer.setOutputProperty(OutputKeys.ENCODING,"gb2312");

059            transformer.setOutputProperty(OutputKeys.INDENT,"yes");

060            PrintWriter pw =new PrintWriter(newFileOutputStream(fileName));

061            StreamResult result =new StreamResult(pw);

062            transformer.transform(source, result);

063            System.out.println("生成XML文件成功!");

064        }catch (TransformerConfigurationException e) {

065            System.out.println(e.getMessage());

066        }catch (IllegalArgumentException e) {

067            System.out.println(e.getMessage());

068        }catch (FileNotFoundException e) {

069            System.out.println(e.getMessage());

070        }catch (TransformerException e) {

071            System.out.println(e.getMessage());

072        }

073    }

074  

075    public void parserXml(String fileName) {

076        try{

077            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

078            DocumentBuilder db = dbf.newDocumentBuilder();

079            Document document = db.parse(fileName);

080            NodeList employees = document.getChildNodes();

081            for(int i = 0; i < employees.getLength(); i++) {

082                Node employee = employees.item(i);

083                NodeList employeeInfo = employee.getChildNodes();

084                for(int j = 0; j < employeeInfo.getLength(); j++) {

085                    Node node = employeeInfo.item(j);

086                    NodeList employeeMeta = node.getChildNodes();

087                    for(int k = 0; k < employeeMeta.getLength(); k++) {

088                        System.out.println(employeeMeta.item(k).getNodeName()

089                                +":" + employeeMeta.item(k).getTextContent());

090                    }

091                }

092            }

093            System.out.println("解析完毕");

094        }catch (FileNotFoundException e) {

095            System.out.println(e.getMessage());

096        }catch (ParserConfigurationException e) {

097            System.out.println(e.getMessage());

098        }catch (SAXException e) {

099            System.out.println(e.getMessage());

100        }catch (IOException e) {

101            System.out.println(e.getMessage());

102        }

103    }

104}

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；
Java代码：

view source

print?

001import java.io.FileInputStream;   

002import java.io.FileNotFoundException;   

003import java.io.IOException;   

004import java.io.InputStream;   

005import javax.xml.parsers.ParserConfigurationException;   

006import javax.xml.parsers.SAXParser;   

007import javax.xml.parsers.SAXParserFactory;   

008import org.xml.sax.Attributes;   

009import org.xml.sax.SAXException;   

010import org.xml.sax.helpers.DefaultHandler;   

011   

012public class SaxDemo implements XmlDocument {   

013    public void createXml(String fileName) {   

014        System.out.println("<<"+filename+">>");   

015    }   

016    public void parserXml(String fileName) {   

017        SAXParserFactory saxfac = SAXParserFactory.newInstance();   

018        try{   

019            SAXParser saxparser = saxfac.newSAXParser();   

020            InputStream is =new FileInputStream(fileName);   

021            saxparser.parse(is,new MySAXHandler());   

022        }catch (ParserConfigurationException e) {   

023            e.printStackTrace();   

024        }catch (SAXException e) {   

025            e.printStackTrace();   

026        }catch (FileNotFoundException e) {   

027            e.printStackTrace();   

028        }catch (IOException e) {   

029            e.printStackTrace();   

030        }   

031    }   

032}   

033public class MySAXHandler extends DefaultHandler {   

034    boolean hasAttribute =false;   

035    Attributes attributes =null;   

036    public void startDocument() throws SAXException {   

037        System.out.println("文档开始打印了");   

038    }   

039    public void endDocument() throws SAXException {   

040        System.out.println("文档打印结束了");   

041    }   

042    public void startElement(String uri, String localName, String qName,   Attributes attributes) throws SAXException {   

043        if(qName.equals("employees")) {   

044            return;   

045        }   

046        if(qName.equals("employee")) {   

047            System.out.println(qName);   

048        }   

049        if(attributes.getLength() > 0) {   

050            this.attributes = attributes;   

051            this.hasAttribute =true;   

052        }   

053    }   

054    public void endElement(String uri, String localName, String qName)   throws SAXException {   

055        if(hasAttribute && (attributes != null)) {   

056            for(int i = 0; i < attributes.getLength(); i++) {   

057                System.out.println(attributes.getQName(0)   + attributes.getValue(0));   

058            }   

059        }   

060    }  

061    public void characters(char[] ch, int start, int length)   throws SAXException {   

062        System.out.println(newString(ch, start, length));   

063    }   

064}  

065  

066import java.io.FileInputStream; 

067import java.io.FileNotFoundException; 

068import java.io.IOException; 

069import java.io.InputStream; 

070import javax.xml.parsers.ParserConfigurationException; 

071import javax.xml.parsers.SAXParser; 

072import javax.xml.parsers.SAXParserFactory; 

073import org.xml.sax.Attributes; 

074import org.xml.sax.SAXException; 

075import org.xml.sax.helpers.DefaultHandler; 

076  

077public class SaxDemo implements XmlDocument { 

078    public void createXml(String fileName) { 

079        System.out.println("<<"+filename+">>"); 

080    } 

081    public void parserXml(String fileName) { 

082        SAXParserFactory saxfac = SAXParserFactory.newInstance(); 

083        try{ 

084            SAXParser saxparser = saxfac.newSAXParser(); 

085            InputStream is =new FileInputStream(fileName); 

086            saxparser.parse(is,new MySAXHandler()); 

087        }catch (ParserConfigurationException e) { 

088            e.printStackTrace(); 

089        }catch (SAXException e) { 

090            e.printStackTrace(); 

091        }catch (FileNotFoundException e) { 

092            e.printStackTrace(); 

093        }catch (IOException e) { 

094            e.printStackTrace(); 

095        } 

096    } 

097} 

098public class MySAXHandler extends DefaultHandler { 

099    boolean hasAttribute =false; 

100    Attributes attributes =null; 

101    public void startDocument() throws SAXException { 

102        System.out.println("文档开始打印了"); 

103    } 

104    public void endDocument() throws SAXException { 

105        System.out.println("文档打印结束了"); 

106    } 

107    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { 

108        if(qName.equals("employees")) { 

109            return; 

110        } 

111        if(qName.equals("employee")) { 

112            System.out.println(qName); 

113        } 

114        if(attributes.getLength() > 0) { 

115            this.attributes = attributes; 

116            this.hasAttribute =true; 

117        } 

118    } 

119    public void endElement(String uri, String localName, String qName) throws SAXException { 

120        if(hasAttribute && (attributes != null)) { 

121            for(int i = 0; i < attributes.getLength(); i++) { 

122                System.out.println(attributes.getQName(0) + attributes.getValue(0)); 

123            } 

124        } 

125    } 

126    public void characters(char[] ch, int start, int length) throws SAXException { 

127        System.out.println(newString(ch, start, length)); 

128    } 

129}

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。
Java代码：

view source

print?

01import java.io.File;

02import java.io.FileWriter;

03import java.io.IOException;

04import java.io.Writer;

05import java.util.Iterator;

06import org.dom4j.Document;

07import org.dom4j.DocumentException;

08import org.dom4j.DocumentHelper;

09import org.dom4j.Element;

10import org.dom4j.io.SAXReader;

11import org.dom4j.io.XMLWriter;

12  

13/** * * @author hongliang.dinghl * Dom4j 生成XML文档与解析XML文档 */

14public class Dom4jDemo implements XmlDocument {

15    public void createXml(String fileName) {

16        Document document = DocumentHelper.createDocument();

17        Element employees = document.addElement("employees");

18        Element employee = employees.addElement("employee");

19        Element name = employee.addElement("name");

20        name.setText("ddvip");

21        Element sex = employee.addElement("sex");

22        sex.setText("m");

23        Element age = employee.addElement("age");

24        age.setText("29");

25        try{

26            Writer fileWriter =new FileWriter(fileName);

27            XMLWriter xmlWriter =new XMLWriter(fileWriter);

28            xmlWriter.write(document);

29            xmlWriter.close();

30        }catch (IOException e) {

31            System.out.println(e.getMessage());

32        }

33    }

34  

35    public void parserXml(String fileName) {

36        File inputXml =new File(fileName);

37        SAXReader saxReader =new SAXReader();

38        try{

39            Document document = saxReader.read(inputXml);

40            Element employees = document.getRootElement();

41            for(Iterator i = employees.elementIterator(); i.hasNext();) {

42                Element employee = (Element) i.next();

43                for(Iterator j = employee.elementIterator(); j.hasNext();) {

44                    Element node = (Element) j.next();

45                    System.out.println(node.getName() +":" + node.getText());

46                }

47            }

48        }catch (DocumentException e) {

49            System.out.println(e.getMessage());

50        }

51        System.out.println("dom4j parserXml");

52    }

53}

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。

view source

print?

01import java.io.FileNotFoundException;

02import java.io.FileOutputStream;

03import java.io.IOException;

04import java.util.List;

05import org.jdom.Document;

06import org.jdom.Element;

07import org.jdom.JDOMException;

08import org.jdom.input.SAXBuilder;

09import org.jdom.output.XMLOutputter;

10  

11public class JDomDemo implements XmlDocument {

12    public void createXml(String fileName) {

13        Document document;

14        Element root;

15        root =new Element("employees");

16        document =new Document(root);

17        Element employee =new Element("employee");

18        root.addContent(employee);

19        Element name =new Element("name");

20        name.setText("ddvip");

21        employee.addContent(name);

22        Element sex =new Element("sex");

23        sex.setText("m");

24        employee.addContent(sex);

25        Element age =new Element("age");

26        age.setText("23");

27        employee.addContent(age);

28        XMLOutputter XMLOut =new XMLOutputter();

29        try{

30            XMLOut.output(document,new FileOutputStream(fileName));

31        }catch (FileNotFoundException e) {

32            e.printStackTrace();

33        }catch (IOException e) {

34            e.printStackTrace();

35        }

36    }

37  

38    public void parserXml(String fileName) {

39        SAXBuilder builder =new SAXBuilder(false);

40        try{

41            Document document = builder.build(fileName);

42            Element employees = document.getRootElement();

43            List employeeList = employees.getChildren("employee");

44            for(int i = 0; i < employeeList.size(); i++) {

45                Element employee = (Element) employeeList.get(i);

46                List employeeInfo = employee.getChildren();

47                for(int j = 0; j < employeeInfo.size(); j++) {

48                    System.out.println(((Element) employeeInfo.get(j))

49                            .getName()

50                            +":" + ((Element) employeeInfo.get(j)).getValue());

51                }

52            }

53        }catch (JDOMException e) {

54            e.printStackTrace();

55        }catch (IOException e) {

56            e.printStackTrace();

57        }

58    }

59}

关键字：javaxml java解析xml dom解析 xslt sax JDOM DOM4J