1.生成url
2.获取google返回的网络信息 new InputSource(aURL.openStream())
3.生成解析xml的处理器
4.解析xml
5.封装解析后的xml文件
6.根据解析后的数据，生成url，获取google返回的天气图标，赋值给图片

代码：

/*获取用户输入的城市名称*/
String city = ((EditText) findViewById(R.id.input))
.getText().toString();

/*组成URL字符串*/
//中文：http://www.google.com/ig/api hl=zh-cn&weather=
//英文：http://www.google.com/ig/api weather=
String queryString = "http://www.google.com/ig/api weather="
+ city;
/*将可能的空格替换为"%20"*/
URL aURL = new URL(queryString.replace(" ", "%20"));

/* 从SAXParserFactory获取SAXParser*/
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();

/* 从SAXParser得到XMLReader*/
XMLReader xr = sp.getXMLReader();

/*
* 创建GoogleWeatherHandler，以便解析XML内容
*/
GoogleWeatherHandler gwh = new GoogleWeatherHandler();
xr.setContentHandler(gwh);

/* 解析XML文件内容 */
xr.parse(new InputSource(aURL.openStream()) );

TextView tv1 = (TextView)findViewById(R.id.tem);
tv1.setText("温度：" + gwh.getCurrentTemp() + "摄氏度");

TextView tv2 = (TextView)findViewById(R.id.weather);
tv2.setText(gwh.getCurrentCondition());

TextView tv3 = (TextView)findViewById(R.id.hum);
tv3.setText(""+ gwh.getCurrentHum() );


URL iconURL = new URL("http://www.google.com"+ gwh.getIconURL());
URLConnection conn = iconURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
//设置icon
ImageView iv = (ImageView)findViewById(R.id.iconOfWeather);
Bitmap bm = null;
bm = BitmapFactory.decodeStream(bis);
iv.setImageBitmap(bm);
bis.close();
is.close();

分析google返回的xml的处理类代码：
private boolean in_current_conditions = false;
private boolean in_forecast_conditions = false;

private Integer current_temp;
private String current_condition;
private String current_hum;
private String iconURL;

@Override
public void startDocument() throws SAXException {

}

@Override
public void endDocument() throws SAXException {

}