解析速度快，占用内存少，采用事件驱动，即不需要加载完整个文档，而是按内容顺序解析文档，在此过程中，其会判断当前读到的内容是否符合XML语法定义
AD：
Android平台上可以使用SimpleAPIforXML(SAX),DocumentObjectModel(DOM)和Android附带的pull解析器解析XML文件
众所周知，,DOM解析方式很耗内存,优先使用SAX或者pull
SAX:
解析速度快，占用内存少，采用事件驱动，即不需要加载完整个文档，而是按内容顺序解析文档，在此过程中，其会判断当前读到的内容是否符合XML语法定义，如果符合就会触发事件，所谓事件，其实就是一些callback方法，具体方法含义比较简单,看文档即可，定义在DefaultHandler接口中（SAX已内置到JDK5.0中）
待解析xml文件musics.xml:
<?xmlversion="1.0"encoding="utf-8"?> <musics> <musicid="1"> <name>黑色幽默</name> <albumName>Jay</albumName> <year>2000</year> </music> <musicid="2"> <name>爱在西元前</name> <albumName>范特西</albumName> <year>2001</year> </music> <musicid="3"> <name>回到过去</name> <albumName>八度空间</albumName> <year>2002</year> </music> <musicid="4"> <name>东风破</name> <albumName>叶惠美</albumName> <year>2003</year> </music> <musicid="5"> <name>七里香</name> <albumName>七里香</albumName> <year>2004</year> </music> <musicid="6"> <name>一路向北</name> <albumName>十一月的萧邦</albumName> <year>2005</year> </music> </musics>
实体类MusicEntity就不贴了，四个属性，上面的xml中也可以看出.
实现了DefaultHandler接口的SaxHandler:
publicclassSaxHandlerextendsDefaultHandler{ privatestaticfinalStringTAG="lanyan"; privateList<MusicEntity>musics; privateMusicEntitymusic; privateStringpreTag; @Override publicvoidstartDocument()throwsSAXException{ musics=newArrayList<MusicEntity>(); } @Override publicvoidstartElement(Stringuri,StringlocalName,StringqName, Attributesattributes)throwsSAXException{ if("music".equals(localName)){ music=newMusicEntity(); music.setId(Integer.parseInt(attributes.getValue("id"))); } preTag=localName; } @Override publicvoidcharacters(char[]ch,intstart,intlength) throwsSAXException{ if(null!=music){ Stringstr=newString(ch,start,length); if("name".equals(preTag)){ music.setName(str); }elseif("albumName".equals(preTag)){ music.setAlbumName(str); }elseif("year".equals(preTag)){ music.setYear(Integer.parseInt(str)); } } } @Override publicvoidendElement(Stringuri,StringqName) throwsSAXException{ if("music".equals(localName)&&null!=music){ musics.add(music); music=null; } preTag=null; } @Override publicvoidendDocument()throwsSAXException{ } publicList<MusicEntity>getMusics(){ returnmusics; } }
对外提供SAX解析服务的接口SaxService：
publicclassSaxService{ publicstaticList<MusicEntity>readXml(InputStreamis)throwsException{ SAXParserFactorysaxFactory=SAXParserFactory.newInstance(); SAXParserparser=saxFactory.newSAXParser(); SaxHandlerhandler=newSaxHandler(); parser.parse(is,handler); returnhandler.getMusics(); } }
测试方法：
publicvoidtestSaxRead(){ InputStreamis=XmlPaserTest.class.getClassLoader().getResourceAsStream("musics.xml"); try{ List<MusicEntity>musics=SaxService.readXml(is); for(MusicEntitymusic:musics){ Log.i("lanyan",music.toString()); } }catch(Exceptione){ e.printStackTrace(); } }
Pull:
同样是事件驱动，不同的是不需要实现什么handler接口,标签之间value的读取也不需要通过类似characters(...)的回调方法，相关API已经封转好了
对外提供PULL解析服务的接口PullService中的xml解析方法：
publicstaticList<MusicEntity>readXml(InputStreamis)throwsException{ List<MusicEntity>musics=null; XmlPullParserparser=Xml.newPullParser(); parser.setInput(is,"UTF-8"); inteventCode=parser.getEventType(); MusicEntitymusic=null; while(eventCode!=XmlPullParser.END_DOCUMENT){ switch(eventCode){ caseXmlPullParser.START_DOCUMENT: musics=newArrayList<MusicEntity>(); break; caseXmlPullParser.START_TAG: if("music".equals(parser.getName())){ music=newMusicEntity(); music.setId(newInteger(parser.getAttributeValue(0))); }elseif(music!=null){ if("name".equals(parser.getName())){ music.setName(parser.nextText()); }elseif("albumName".equals(parser.getName())){ music.setAlbumName(parser.nextText()); }elseif("year".equals(parser.getName())){ music.setYear(Integer.parseInt(parser.nextText())); } } break; caseXmlPullParser.END_TAG: if("music".equals(parser.getName())&&music!=null){ musics.add(music); music=null; } break; } eventCode=parser.next(); } returnmusics; }
使用PULL解析方式生成xml文件:
PullService中的xml生成方法:
/** *Pull生成xml数据 *@parampersons *@paramwriter *@throwsException */ publicstaticvoidwriteXml(List<MusicEntity>musics,Writerwriter) throwsException{ XmlSerializerserializer=Xml.newSerializer(); serializer.setOutput(writer); serializer.startDocument("UTF-8",true); serializer.startTag(null,"musics"); for(MusicEntitymusic:musics){ serializer.startTag(null,"music"); serializer.attribute(null,"id",String.valueOf(music.getId())); serializer.startTag(null,"name"); serializer.text(music.getName()); serializer.endTag(null,"name"); serializer.startTag(null,"albumName"); serializer.text(music.getAlbumName()); serializer.endTag(null,"albumName"); serializer.startTag(null,"year"); serializer.text(String.valueOf(music.getYear())); serializer.endTag(null,"year"); serializer.endTag(null,"music"); } serializer.endTag(null,"musics"); serializer.endDocument(); writer.flush(); writer.close(); }
测试方法:
publicvoidtestPullWrite()throwsException{ List<MusicEntity>musics=newArrayList<MusicEntity>(); MusicEntitymusic1=newMusicEntity(); music1.setId(1); music1.setName("七里香"); music1.setAlbumName("七里香"); music1.setYear(2004); musics.add(music1); MusicEntitymusic2=newMusicEntity(); music2.setId(1); music2.setName("一路向北"); music2.setAlbumName("十一月的萧邦"); music2.setYear(2005); musics.add(music2); StringWriterwriter=newStringWriter(); PullService.writeXml(musics,writer); Log.i("lanyan",writer.toString()); }
输出结果：
<?xmlversion='1.0'encoding='UTF-8'standalone='yes'?><musics><musicid="1"><name>七里香</name><albumName>七里香</albumName><year>2004</year></music><musicid="1"><name>一路向北</name><albumName>十一月的萧邦</albumName><year>2005</year></music></musics>
（编辑：李大同）
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