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 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(),IDlength()); handlerendElement("","ID"); attrclear(); handlerstartElement("","name",attr); String name = persons[i]getname(); handlercharacters(nametochararray(),namelength()); handlerendElement("","name"); attrclear(); handlerstartElement("","blog",attr); String blog = persons[i]getBlog(); handlercharacters(blogtochararray(),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,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 length) throws SAXException { supercharacters(ch,length); if (null != tag) { String value = new String(ch,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 qname) throws SAXException { if("person"equals(qname)) { personsListadd(person); person = null; } tag = null; superendElement(uri,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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