java获得rss订阅中的信息

public class Jdom {
public static void main(String[] args){
try{
URL url = new URL("http://www.google.com/ig/api?hl=zh_cn&weather=tianjin");
InputStream instr = url.openStream();
String s,str;
BufferedReader in = new BufferedReader(new InputStreamReader(instr));
StringBuffer sb = new StringBuffer();

Writer out =new BufferedWriter(new OutputStreamWriter(new FileOutputStream("weater.txt"),"utf-8"));
while((s=in.readLine())!=null){
sb.append(s);
}
str = new String(sb);
out.write(str);
out.close();
in.close();
}catch(Exception e){
e.printStackTrace();
}

File f = new File("weater.txt");//暂存的文件
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
String str = null;
try{
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(f);
NodeList nl = (NodeList)doc.getElementsByTagName("forecast_conditions");//需要的节点的tagname
NodeList n2 = nl.item(0).getChildNodes();
str = n2.item(4).getAttributes().item(0).getNodeValue()+","+n2.item(1).getAttributes().item(0).getNodeValue()+"°C";
System.out.println(str);
}catch(Exception e){

}
}
}