WeatherBinder.java

/***
  Copyright (c) 2010-2012 CommonsWare, LLC
  
  Licensed under the Apache License, Version 2.0 (the "License"); you may
  not use this file except in compliance with the License. You may obtain
  a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

package com.commonsware.android.weather;

import java.io.StringReader;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import android.location.Location;
import android.os.AsyncTask;
import android.os.Binder;

public class WeatherBinder extends Binder {
  private String format=null;
  
  WeatherBinder(String format) {
    this.format=format;
  }

  void getForecast(Location loc, WeatherListener listener) {
    new FetchForecastTask(listener).execute(loc);
  }
  
  private ArrayList<Forecast> buildForecasts(String raw) throws Exception {
    ArrayList<Forecast> forecasts=new ArrayList<Forecast>();
    DocumentBuilder builder=DocumentBuilderFactory
                              .newInstance()
                              .newDocumentBuilder();
    Document doc=builder.parse(new InputSource(new StringReader(raw)));
    NodeList times=doc.getElementsByTagName("start-valid-time");
    
    for (int i=0;i<times.getLength();i++) {
      Element time=(Element)times.item(i);
      Forecast forecast=new Forecast();
      
      forecasts.add(forecast);
      forecast.setTime(time.getFirstChild().getNodeValue());
    }
    
    NodeList temps=doc.getElementsByTagName("value");
    
    for (int i=0;i<temps.getLength();i++) {
      Element temp=(Element)temps.item(i);
      Forecast forecast=forecasts.get(i);
      
      forecast.setTemp(new Integer(temp.getFirstChild().getNodeValue()));
    }
    
    NodeList icons=doc.getElementsByTagName("icon-link");
    
    for (int i=0;i<icons.getLength();i++) {
      Element icon=(Element)icons.item(i);
      Forecast forecast=forecasts.get(i);
      
      forecast.setIcon(icon.getFirstChild().getNodeValue());
    }
    
    return(forecasts);
  }
  
  class FetchForecastTask extends AsyncTask<Location, Void, ArrayList<Forecast>> {
    Exception e=null;
    WeatherListener listener=null;
    
    FetchForecastTask(WeatherListener listener) {
      this.listener=listener;
    }
    
    @Override
    protected ArrayList<Forecast> doInBackground(Location... locs) {
      DefaultHttpClient client=new DefaultHttpClient();
      ArrayList<Forecast> result=null;
      
      try {
        Location loc=locs[0];
        String url=String.format(format, loc.getLatitude(),
                                  loc.getLongitude());
        HttpGet getMethod=new HttpGet(url);
        ResponseHandler<String> responseHandler=new BasicResponseHandler();
        String responseBody=client.execute(getMethod, responseHandler);
        
        result=buildForecasts(responseBody);
      }
      catch (Exception e) {
        this.e=e;
      }
      
      client.getConnectionManager().shutdown();
      
      return(result);
    }
    
    @Override
    protected void onPostExecute(ArrayList<Forecast> forecast) {
      if (listener!=null) {
        if (forecast!=null) {
          listener.updateForecast(forecast);
        }
        
        if (e!=null) {
          listener.handleError(e);
        }
      }
    }
  }
}