Android使用SAX解析XML与读写操作示例
在手机操作里，为了节省空间，多数采用xml做为存储介质，因此，如何用Android解析XML与使用Android读写XML操作，变的相当重要，android操作xml同时也是基础操作之一，对于Android手机开者而言，这是一项必备的基础知识。同时，android平台为此也提供了很多API用于操作xml，如Simple APIfor XML,简称（SAX）、Document Object Model，简称DOM等方式。
本节为您介绍使用SAX来解析与进行Android的XML读写操作：
SAX在读取xml文件时会触发事件，通过事件来处理当前读取到的内容。
这一点区别于dom，dom是全部读取完后在进行操作。
下面来个示例：读取google天气预报：
读取地址：http://www.google.com/ig/api?weather=guangzhou&hl=zh-cn
通过网址URL取得天气的XML代码，然后再通过SAX进行读取：
首先根据XML文件抽象出一个类来，获取到的XML代码如下：
<?xml version="1.0" ?>
<xml_api_reply version="1">
<weather module_id="0" tab_id="0" mobile_row="0" mobile_zipped="1"
row="0" section="0">
<forecast_information>
<city data="guangzhou, guangzhou" />
<postal_code data="guangzhou" />
<latitude_e6 data="" />
<longitude_e6 data="" />
<forecast_date data="2010-12-27" />
<current_date_time data="2010-12-28 04:00:00 +0000" />
<unit_system data="SI" />
</forecast_information>
<current_conditions>
<condition data="晴" />
<temp_f data="28" />
<temp_c data="-2" />
<humidity data="湿度： 27%" />
<icon data="/ig/images/weather/sunny.gif" />
<wind_condition data="风向： 西北、风速：7 米/秒" />
</current_conditions>
<forecast_conditions>
<day_of_week data="周一" />
<low data="-12" />
<high data="6" />
<icon data="/ig/images/weather/sunny.gif" />
<condition data="晴" />
</forecast_conditions>
<forecast_conditions>
<day_of_week data="周二" />
<low data="-11" />
<high data="1" />
<icon data="/ig/images/weather/sunny.gif" />
<condition data="晴" />
</forecast_conditions>
<forecast_conditions>
<day_of_week data="周三" />
<low data="-11" />
<high data="2" />
<icon data="/ig/images/weather/chance_of_snow.gif" />
<condition data="可能降雪" />
</forecast_conditions>
<forecast_conditions>
<day_of_week data="周四" />
<low data="-13" />
<high data="-2" />
<icon data="/ig/images/weather/sunny.gif" />
<condition data="晴" />
</forecast_conditions>
</weather>
</xml_api_reply>
时间不同，内容可能有所变化，但格式仍是一样的，以下便是根据格式简化与抽象出来的操作类：
package com.SAXXMLReader;
public class NowWeather {
private String condition;
private String temp_f;
private String temp_c;
private String humidity;
private String icon;
private String wind_condition;
public NowWeather() {
}
public void setcondition(String condition) {
this.condition = condition;
}
public void settempf(String temp_f) {
this.temp_f = temp_f;
}
public void settempc(String temp_c) {
this.temp_c = temp_c;
}
public void sethumidity(String humidity) {
this.humidity = humidity;
}
public void seticon(String icon) {
this.icon = icon;
}
public void setwindcondition(String wind_condition) {
this.wind_condition = wind_condition;
}
public String getNowWeather()
{
StringBuilder strBuilder = new StringBuilder();
strBuilder.append(condition+"\n");
strBuilder.append(temp_f+"\n");
strBuilder.append(temp_c+"\n");
strBuilder.append(humidity+"\n");
strBuilder.append(icon+"\n");
strBuilder.append(wind_condition+"\n");
return strBuilder.toString();
}
}
此类根据习惯编写而成，用于保存GET到的数据，当然形式多种多样，大伙根据自己的习惯即可。
由于SAX必须要有DefaultHandler类的继承,因此我们继承之，代码如下：
package com.SAXXMLReader;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import android.util.Log;
public class WeatherHandler extends DefaultHandler {
private final String CURRENT_CONDITIONS = "current_conditions"; // 当前
private final String forecast_conditions = "forecast_conditions"; // 当前
// 实时天气信息
private boolean is_Current_Conditions = false;
// 预报天气信息
private boolean is_Forecast_Conditions = false;
NowWeather nowWeather = new NowWeather();
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
super.characters(ch, start, length);
}
@Override
public void startDocument() throws SAXException {
super.startDocument();
}
public WeatherHandler() {
}
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
String dataAttribute = "OK";
if (localName.equals(CURRENT_CONDITIONS)) {
Log.d("WeatherHandler", localName);
is_Current_Conditions = true;
} else if (localName.equals(forecast_conditions)) {
is_Current_Conditions = false;
} else {
dataAttribute = attributes.getValue("data");
if (this.is_Current_Conditions) {
Log.d("WeatherHandler_1", dataAttribute);
if (localName.equals("condition")) {
this.nowWeather.setcondition(dataAttribute);
} else if (localName.equals("temp_f")) {
this.nowWeather.settempf(dataAttribute);
} else if (localName.equals("temp_c")) {
this.nowWeather.settempc(dataAttribute);
} else if (localName.equals("humidity")) {
this.nowWeather.sethumidity(dataAttribute);
} else if (localName.equals("icon")) {
this.nowWeather.seticon(dataAttribute);
} else if (localName.equals("wind_condition")) {
this.nowWeather.setwindcondition(dataAttribute);
}
} else if (this.is_Forecast_Conditions) {
Log.d("WeatherHandler_1", dataAttribute);
}
}
}
public String getNowWeather() {
return nowWeather.getNowWeather();
}
@Override
public void endDocument() throws SAXException {
super.endDocument();
}
@Override
public void endElement(String uri, String localName, String name)
throws SAXException {
}
}
以上代码用于实现Android读取Xml，并保存到类中，下面我们进行调用，然后取得内容：
SAXParserFactory faction =SAXParserFactory.newInstance();
SAXParser parser = faction.newSAXParser();
WeatherHandler handler = new WeatherHandler();
XMLReader reader = parser.getXMLReader();
reader.setContentHandler(handler);
URL url = new URL(SRC);
HttpURLConnection httpconn = (HttpURLConnection) url.openConnection();
InputStream inStream =httpconn.getInputStream();
InputStreamReader isReader = new InputStreamReader(inStream,"GBK");
InputSource inputSource = new InputSource(isReader);
reader.parse(inputSource);
text1.setText(handler.getNowWeather());
以上的示例中，直接用网址URL进行读取，当然读取本机的XML也是一样的道理，大伙应该可以理解，本节示例到此结束，希望对新手有所帮助。
2011/9/5 9:40:05 | Android Dev | |