android sax解析xml Android创建与解析XML(三)——详解Sax方式
阳光岛主 人气:01. 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;
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
/** 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://blogcsdnnet/sunboy_2050"); persons[1] = new Person(2, "baidu", "http://wwwbaiducom"); persons[2] = new Person(3, "google", "http://wwwgooglecom"); try { SAXTransformerFactory factory = (SAXTransformerFactory)SAXTransformerFactorynewInstance(); TransformerHandler handler = factorynewTransformerHandler(); Transformer transformer = handlergetTransformer(); // 设置xml属性 transformersetOutputProperty(OutputKeysINDENT, "yes"); transformersetOutputProperty(OutputKeysENCODING, "utf-8"); transformersetOutputProperty(OutputKeysVERSION, "0"); StreamResult result = new StreamResult(xmlWriter); // 保存创建的xml handlersetResult(result); handlerstartDocument(); AttributesImpl attr = new AttributesImpl(); attrclear(); attraddAttribute("", "", "author", "", "homer"); attraddAttribute("", "", "date", "", "2012-04-27"); handlerstartElement("", "", "root", attr); int personsLen = personslength; for(int i=0; i<personsLen; i++){ attrclear(); handlerstartElement("", "", "person", attr); attrclear(); handlerstartElement("", "", "id", attr); String id = persons[i]getId() + ""; handlercharacters(idtoCharArray(), 0, idlength()); handlerendElement("", "", "id"); attrclear(); handlerstartElement("", "", "name", attr); String name = persons[i]getName(); handlercharacters(nametoCharArray(), 0, namelength()); handlerendElement("", "", "name"); attrclear(); handlerstartElement("", "", "blog", attr); String blog = persons[i]getBlog(); handlercharacters(blogtoCharArray(), 0, bloglength()); handlerendElement("", "", "blog"); handlerendElement("", "", "person"); } handlerendElement("", "", "root"); handlerendDocument(); } catch (TransformerFactoryConfigurationError e) { // SAXTransformerFactorynewInstance eprintStackTrace(); } catch (TransformerConfigurationException e) { // factorynewTransformerHandler eprintStackTrace(); } catch (IllegalArgumentException e) { // transformersetOutputProperty eprintStackTrace(); } catch (SAXException e) { // handlerstartDocument eprintStackTrace(); } catch (Exception e) { eprintStackTrace(); } savedXML(fileName, xmlWritertoString()); return xmlWritertoString(); }
运行结果:
3、Sax解析XML
/** Sax方式,解析 XML */ public String saxResolveXML(){ StringWriter xmlWriter = new StringWriter(); InputStream is = readXML(fileName); try { SAXParserFactory factory = SAXParserFactorynewInstance(); SAXParser saxParser = factorynewSAXParser(); PersonHandler handler = new PersonHandler(); // person处理Handler saxParserparse(is, handler); // handler解析xml // 获取解析的xml String xmlHeader = handlergetXMLHeader(); xmlWriterappend(xmlHeader); List<Person> personsList = handlergetPersons(); int personsLen = personsListsize(); for(int i=0; i<personsLen; i++){ xmlWriterappend(personsListget(i)toString())append("\n"); } } catch (FactoryConfigurationError e) { // SAXParserFactorynewInstance eprintStackTrace(); } catch (ParserConfigurationException e) { // factorynewSAXParser eprintStackTrace(); } catch (SAXException e) { // factorynewSAXParser eprintStackTrace(); } catch (IllegalArgumentException e) { // saxParserparse eprintStackTrace(); } catch (IOException e) { // saxParserparse eprintStackTrace(); } catch (Exception e) { eprintStackTrace(); } return xmlWritertoString(); } /** 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 xmlHeadertoString(); } /** 返回解析的Person实例数组 */ public List<Person> getPersons(){ return personsList; } @Override public void startDocument() throws SAXException{ superstartDocument(); personsList = new ArrayList<Person>(); xmlHeader = new StringBuffer(); } @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException{ superstartElement(uri, localName, qName, attributes); if("root"equals(localName)) { String attrAuthor = attributesgetValue(0); String attrDate = attributesgetValue(1); xmlHeaderappend("root")append("\t\t"); xmlHeaderappend(attrAuthor)append("\t"); xmlHeaderappend(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 { supercharacters(ch, start, length); if (null != tag) { String value = new String(ch, start, length); Systemoutprintln("value = " + value); if ("id"equals(tag)) { personsetId(new Integer(value)); } else if ("name"equals(tag)) { personsetName(value); } else if ("blog"equals(tag)) { personsetBlog(value); } } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { if("person"equals(qName)) { personsListadd(person); person = null; } tag = null; superendElement(uri, localName, qName); } @Override public void endDocument() throws SAXException{ // personsList = null; superendDocument(); } }
运行结果:
4、Person类
请参见前文Android 创建与解析XML(二)—— Dom方式 【4、Person类】
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