java解析xml文件方法

    对xml数据的解析，在网络程序中经常会用到。在这里介绍SAX方法来处理xml文档。SAX是基于事件的，由回调机制实现。
    在这里需要解析的文件mp3.xml

<?xml version="1.0" encoding="ISO-8859-1"?>

<resources>
	<resource>
		<id>0001</id>
		<mp3.name>Fayray-I Wanna Be Free.mp3</mp3.name>
		<mp3.size>4867102</mp3.size>
		<lrc.name>Fayray-I Wanna Be Free.lrc</lrc.name>
		<lrc.size>1453</lrc.size>
	</resource>
	<resource>
		<id>0002</id>
		<mp3.name>teens-fire_fly.mp3</mp3.name>
		<mp3.size>2999636</mp3.size>
		<lrc.name>teens-fire_fly.lrc</lrc.name>
		<lrc.size>1986</lrc.size>
	</resource>
</resources>

    首先，需定义一个Mp3Info类，用于存放解析后的数据。Mp3Info.java

import java.io.Serializable;

public class Mp3Info implements Serializable{
	private static final long serialVersionUID = 1L;
	private String id;
	private String mp3Name;
	private String mp3Size;
	private String lrcName;
	private String lrcSize;
	
	public Mp3Info() {
		super();
	}
	public Mp3Info(String id, String mp3Name, String mp3Size, String lrcName,
			String lrcSize) {
		super();
		this.id = id;
		this.mp3Name = mp3Name;
		this.mp3Size = mp3Size;
		this.lrcName = lrcName;
		this.lrcSize = lrcSize;
	}
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getMp3Name() {
		return mp3Name;
	}
	public void setMp3Name(String mp3Name) {
		this.mp3Name = mp3Name;
	}
	public String getMp3Size() {
		return mp3Size;
	}
	public void setMp3Size(String mp3Size) {
		this.mp3Size = mp3Size;
	}
	public String getLrcName() {
		return lrcName;
	}
	public void setLrcName(String lrcName) {
		this.lrcName = lrcName;
	}
	public String getLrcSize() {
		return lrcSize;
	}
	public void setLrcSize(String lrcSize) {
		this.lrcSize = lrcSize;
	}
	
	@Override
	public String toString() {
		return "Mp3Info [id=" + id + ", mp3Name=" + mp3Name + ", mp3Size="
				+ mp3Size + ", lrcName=" + lrcName + ", lrcSize=" + lrcSize
				+ "]";
	}
		
}

定义一个用于解析xml文档的函数，函数名Parse(String xmlStr)。解析后的据存放在一个链表中。

private List<Mp3Info> parse(String xmlStr){
		List<Mp3Info> infos = new ArrayList<Mp3Info>();
		
		SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
		SAXParser parser = null;
		//saxParserFactory.setNamespaceAware(true);
		//saxParserFactory.setValidating(true);

		try {
			parser = saxParserFactory.newSAXParser();		//用于封装JDK提供的解析器
		 }
		 catch(SAXException e) {
		    e.printStackTrace(System.err);
		    System.exit(1);
		 } 
		 catch(ParserConfigurationException e) {
			 e.printStackTrace(System.err);
		     System.exit(1);    
		 }
		 
		 System.out.println("\nStarting parse ...");
		 Mp3ListContentHandler mp3ListContentHandler = new Mp3ListContentHandler(infos);
		 try{	
			parser.parse(new InputSource(new StringReader(xmlStr)), mp3ListContentHandler);
			
			for(Iterator<Mp3Info> iterator = infos.iterator(); iterator.hasNext();){
				Mp3Info mp3Info = (Mp3Info)iterator.next();
				System.out.println(mp3Info);
			}
		 }catch(IOException e) {
			 //System.out.println("--------------->2");
		     e.printStackTrace(System.err);
		 }catch(SAXException e) {
			 //System.out.println("--------------->3");
		     e.printStackTrace(System.err);
		 }
		return infos;
	}

    在Prase()函数中，出现了一个类，mp3ListContentHandler，因此还需要对它进行定义。解析的关键部分都在此类中。

import java.util.List;

import jia.model.Mp3Info;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class Mp3ListContentHandler extends DefaultHandler{

	private List<Mp3Info> infos = null;
	private Mp3Info mp3Info = null;
	private String tagName = null;
	
	//Constructor
	public Mp3ListContentHandler(List<Mp3Info> infos) {
		this.infos = infos;
	}

	public List<Mp3Info> getInfos() {
		return infos;
	}

	public void setInfos(List<Mp3Info> infos) {
		this.infos = infos;
	}


	@Override
	public void characters(char[] ch, int start, int length)
			throws SAXException {
		String temp = new String(ch, start, length);
		//System.out.println("Characters: " + temp);
		
		if (tagName.equals("id")) {
			mp3Info.setId(temp);
		} else if (tagName.equals("mp3.name")) {
			mp3Info.setMp3Name(temp);
		} else if (tagName.equals("mp3.size")) {
			mp3Info.setMp3Size(temp);
		} else if (tagName.equals("lrc.name")) {
			mp3Info.setLrcName(temp);
		} else if (tagName.equals("lrc.size")) {
			mp3Info.setLrcSize(temp);
		}
	}

	@Override
	public void endDocument() throws SAXException {
		//System.out.println("End document");
	}

	@Override
	public void endElement(String uri, String localName, String qName)
			throws SAXException {
		if (qName.equals("resource")) {
			infos.add(mp3Info);
		}
		tagName = "";
		//System.out.println("End element: local name: " + localName + " qname: "
         //        + qName + " uri: "+uri);
	}

	@Override
	public void startDocument() throws SAXException {
		System.out.println("Start document:");
	}

	@Override
	public void startElement(String uri, String localName, String qName,
			Attributes attr) throws SAXException {
		//System.out.println("Start element: local name: " + localName + " qname: " 
         //       + qName + " uri: "+uri);
		int attrCount = attr.getLength();
	    if(attrCount>0) {
	    	System.out.println("Attributes:"); 
	    	for(int i = 0 ; i<attrCount ; i++) {
	    		System.out.println("\tName : " + attr.getQName(i)); 
	    		System.out.println("\tType : " + attr.getType(i)); 
	    		System.out.println("\tValue: " + attr.getValue(i)); 
	    	}
	    }
	    this.tagName = localName;
	    if (tagName.equals("resource")){
			mp3Info = new Mp3Info();
		}
	}
}

     这些代码是在android视频教学中用到的，我做了一些修改。感谢作者的的奉献。如需要解析其他的xml文件，只需按照上面的格式，进行一些修改即可。