Android基础1: Xml文件解析

Android 有三种方式进行解析XML: DOM、SAX、PULL

<1> DOM方式：将xml文档全部读入内存，然后使用DOM API访问树形数据，并获取数据，实现简单，但消耗内存

<2> SAX方式：对文件进行顺序扫描，基于事件驱动型解析方式

<3> PULL方式：Pull与SAX类似，但是Pull可以随时跳出解析，而SAX一旦开始就必须要完成将解析工作

使用SAX方式进行解析XML：

//根据参数url获得输入源，并使用SAX进行解析XML操作
public void SAXParseFile(URL url){
try {
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();

WeatherHandler handler  = new WeatherHandler();
xr.setContentHandler(handler);
InputStreamReader isr = new InputStreamReader(url.openStream(),"UTF-8");
InputSource is = new InputSource(isr);
xr.parse(is);
WeatherSet ws = handler.getWeathers();
} catch(Exception e){
e.printStackTrace();
}
}
public class WeatherHandler extends DefaultHandler{

private  String CURRENT = "current_conditions";
private  String FORECAST = "forecast_conditions";
private WeatherSet ws = null;
boolean isCurrent = false;
boolean isForecast = false;

public WeatherHandler(){

}
public WeatherSet getWeathers(){
return this.ws;
}
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
}

@Override
public void endDocument() throws SAXException {
super.endDocument();
}

@Override
public void startDocument() throws SAXException {

ws  = new WeatherSet();
}

@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
if (localName.equals(CURRENT))
{
this.isCurrent = false;
}
else if (localName.equals(FORECAST))
{
this.isForecast = false;
}
}

@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
System.out.println(localName);
if(localName.equals(CURRENT)){
ws.setCurrent_weather(new CurrentWeather());
isCurrent = true;
}else if(localName.equals(FORECAST)){
ws.getForecast_weathers().add(new ForecastWeather());
isForecast = true;
}else{
String attr = attributes.getValue("data");
if(localName.equals("icon")){
if(isCurrent){
ws.getCurrent_weather().setIcon(attr);
}else if(isForecast){
ws.getLastForecast().setIcon(attr);
}
}
else if(localName.equals("condition")){
if(isCurrent){
ws.getCurrent_weather().setCondition_data(attr);
}else if(isForecast){
ws.getLastForecast().setCondition_data(attr);
}
}
else if(localName.equals("temp_c")){
ws.getCurrent_weather().setTemp_c(attr);
}
else if(localName.equals("temp_f")){
ws.getCurrent_weather().setTemp_f(attr);
}
else if(localName.equals("humidity")){
ws.getCurrent_weather().setHumidity(attr);
}
else if(localName.equals("wind_condition")){
ws.getCurrent_weather().setWind_condition(attr);
}
else if(localName.equals("high")){
ws.getLastForecast().setHigh(attr);
}
else if(localName.equals("low")){
ws.getLastForecast().setLow(attr);
}
else if(localName.equals("day_of_week")){
ws.getLastForecast().setWeek_day(attr);
}
}
}

}