Android 创建与解析XML(三)—— Sax方式

长平狐 发布于 2013/01/06 11:18
阅读 103
收藏 0

1. Sax概述

SAX是一种占用内存少且解析速度快的解析器,它采用的是事件启动,不需要解析完整个文档,而是按照内容顺序看文档某个部分是否符合xml语法,如果符合就触发相应的事件,所谓的事件就是些回调方法(callback),这些方法 定义在ContentHandler中,下面是其主要方法:
startDocument():当遇到文档的时候就触发这个事件 调用这个方法 可以在其中做些预处理工作,如:申请对象资源
endDocument()当结束文档的时候就触发这个事件 调用这个方法 可以在其中做些善后工作,如:释放申请的对象资源
startElement(String namespaceURI, String localName, String qName, Attributes atts)当遇开始标签的时候就会触发这个方法。
endElement(String uri, String localName, String name):当遇到结束标签时触发这个事件,调用此法可以做些善后工作。
charachers(char [] ch, int start, int length)当遇到xml内容时触发这个方法,用new String(ch,start,length)可以接受内容。 

Sax方式创建XML,应用了标准xml构造器 javax.xml.transform.sax.TransformerHandler 事件来创建 XML 文档,需要导入以下内容

javax.xml.transform

javax.xml.transform.sax.SAXTransformerFactory;
javax.xml.transform.sax.TransformerHandler;
javax.xml.transform.Transformer;
javax.xml.transform.TransformerConfigurationException;
javax.xml.transform.TransformerFactoryConfigurationError;
javax.xml.transform.OutputKeys;
javax.xml.transform.stream.StreamResult;
javax.xml.transform.sax.SAXTransformerFactory;

javax.xml.parsers

javax.xml.parsers.SAXParser;

javax.xml.parsers.SAXParserFactory;

javax.xml.parsers.FactoryConfigurationError;

javax.xml.parsers.ParserConfigurationException;

org.xml.sax

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

sdk源码查看路径google code


Sax 创建和解析 XML 的效果图:




2、Sax 创建 XML

首先,SAXTransformerFactory.newInstance() 创建一个工厂实例 factory

接着,factory.newTransformerHandler() 获取 TransformerHandler 的 handler 对象

然后,通过 handler 事件创建handler.getTransformer()、 handler.setResult(result),以及 startDocument()、startElement、characters、endElement、endDocument()等

Code

	/** Sax方式,创建 XML  */
	public String saxCreateXML(){
		StringWriter xmlWriter = new StringWriter();

		Person []persons = new Person[3];		// 创建节点Person对象
		persons[0] = new Person(1, "sunboy_2050", "http://blog.csdn.net/sunboy_2050");
		persons[1] = new Person(2, "baidu", "http://www.baidu.com");
		persons[2] = new Person(3, "google", "http://www.google.com");
		
		try {
			SAXTransformerFactory factory = (SAXTransformerFactory)SAXTransformerFactory.newInstance();
			TransformerHandler handler = factory.newTransformerHandler();
			
			Transformer transformer = handler.getTransformer();		// 设置xml属性
			transformer.setOutputProperty(OutputKeys.INDENT, "yes");
			transformer.setOutputProperty(OutputKeys.ENCODING, "utf-8");
			transformer.setOutputProperty(OutputKeys.VERSION, "1.0");
			
			StreamResult result = new StreamResult(xmlWriter);		// 保存创建的xml
			handler.setResult(result);
			
			handler.startDocument();
			AttributesImpl attr = new AttributesImpl();
			
			attr.clear();
			attr.addAttribute("", "", "author", "", "homer");
			attr.addAttribute("", "", "date", "", "2012-04-27");
			handler.startElement("", "", "root", attr);
			
			int personsLen = persons.length;
			for(int i=0; i<personsLen; i++){
				attr.clear();
				handler.startElement("", "", "person", attr);
				
				attr.clear();
				handler.startElement("", "", "id", attr);
				String id = persons[i].getId() + "";
				handler.characters(id.toCharArray(), 0, id.length());
				handler.endElement("", "", "id");

				attr.clear();
				handler.startElement("", "", "name", attr);
				String name = persons[i].getName();
				handler.characters(name.toCharArray(), 0, name.length());
				handler.endElement("", "", "name");

				attr.clear();
				handler.startElement("", "", "blog", attr);
				String blog = persons[i].getBlog();
				handler.characters(blog.toCharArray(), 0, blog.length());
				handler.endElement("", "", "blog");
				
				handler.endElement("", "", "person");
			}
			
			handler.endElement("", "", "root");
			handler.endDocument();
			
		} catch (TransformerFactoryConfigurationError e) {		// SAXTransformerFactory.newInstance
			e.printStackTrace();
		} catch (TransformerConfigurationException e) {			// factory.newTransformerHandler
			e.printStackTrace();
		} catch (IllegalArgumentException e) {		// transformer.setOutputProperty
			e.printStackTrace();
		} catch (SAXException e) {		// handler.startDocument
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		savedXML(fileName, xmlWriter.toString());
		return xmlWriter.toString();
	}

运行结果:





3、Sax解析XML

Code

	/** Sax方式,解析 XML  */
	public String saxResolveXML(){
		StringWriter xmlWriter = new StringWriter();

		InputStream is = readXML(fileName);
		try {
			SAXParserFactory factory = SAXParserFactory.newInstance();
			SAXParser saxParser = factory.newSAXParser();
			
			PersonHandler handler = new PersonHandler();	// person处理Handler
			saxParser.parse(is, handler);					// handler解析xml
			
			// 获取解析的xml
			String xmlHeader = handler.getXMLHeader();
			xmlWriter.append(xmlHeader);
			
			List<Person> personsList = handler.getPersons();
			int personsLen = personsList.size();
			for(int i=0; i<personsLen; i++){
				xmlWriter.append(personsList.get(i).toString()).append("\n");
			}
			
		} catch (FactoryConfigurationError e) {			// SAXParserFactory.newInstance
			e.printStackTrace();
		} catch (ParserConfigurationException e) {		// factory.newSAXParser
			e.printStackTrace();
		} catch (SAXException e) {			// factory.newSAXParser
			e.printStackTrace();
		} catch (IllegalArgumentException e) {		// saxParser.parse
			e.printStackTrace();
		} catch (IOException e) {			// saxParser.parse
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		return xmlWriter.toString();
	}
	
	/** Handler处理类 */
	private final class PersonHandler extends DefaultHandler{
		private List<Person> personsList = null;	// 保存person
		private Person person = null;
		private StringBuffer xmlHeader;				// 保存xml头部信息
		private String tag = null;			// xml Element
		
		/** 返回解析的xml头部信息 */
		public String getXMLHeader(){
			return xmlHeader.toString();
		}
		
		/** 返回解析的Person实例数组 */
		public List<Person> getPersons(){
			return personsList;
		}
		
		@Override
		public void startDocument() throws SAXException{
			super.startDocument();
			personsList = new ArrayList<Person>();
			xmlHeader = new StringBuffer();
		}
		
		@Override
		public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException{
			super.startElement(uri, localName, qName, attributes);
			if("root".equals(localName)) {
				String attrAuthor = attributes.getValue(0);
				String attrDate = attributes.getValue(1);
				xmlHeader.append("root").append("\t\t");
				xmlHeader.append(attrAuthor).append("\t");
				xmlHeader.append(attrDate).append("\n");
			} else if("person".equals(localName)) {
				person = new Person();
			} 
			tag = localName;
		}
		
		@Override
		public void characters(char[] ch, int start, int length) throws SAXException {
			super.characters(ch, start, length);
			if (null != tag) {
				String value = new String(ch, start, length);
				System.out.println("value = " + value);
				if ("id".equals(tag)) {
					person.setId(new Integer(value));
				} else if ("name".equals(tag)) {
					person.setName(value);
				} else if ("blog".equals(tag)) {
					person.setBlog(value);
				}
			}
		}
		
		@Override
		public void endElement(String uri, String localName, String qName) throws SAXException {
			if("person".equals(qName)) {
				personsList.add(person);
				person = null;
			}
			tag = null;
			super.endElement(uri, localName, qName);
		}
		
		@Override
		public void endDocument() throws SAXException{
//			personsList = null;
			super.endDocument();
		}
	}

运行结果:





4、Person类

请参见前面博客 Android 创建与解析XML(二)—— Dom方式 【4、Person类】



代码下载




参考推荐:

javax.xml.transform.sax

javax.xml.parsers

org.xml.sax

TransformerHandler


sax创建xml

Android 解析XML 之SAX



原文链接:http://blog.csdn.net/sunboy_2050/article/details/7521598
加载中
返回顶部
顶部