BartRunnerAndroid/src/com/dougkeen/bart/GetRealTimeDeparturesTask.java
dkeen@dkeen-laptop c72d07ce3a Now shows fares
2012-01-02 16:08:43 -07:00

138 lines
3.7 KiB
Java

package com.dougkeen.bart;
import java.io.IOException;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.util.List;
import org.apache.commons.io.IOUtils;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.xml.sax.SAXException;
import android.os.AsyncTask;
import android.util.Log;
import android.util.Xml;
import com.dougkeen.bart.data.RealTimeDepartures;
public abstract class GetRealTimeDeparturesTask
extends
AsyncTask<GetRealTimeDeparturesTask.Params, Integer, RealTimeDepartures> {
private final static String ETD_URL = "http://api.bart.gov/api/etd.aspx?cmd=etd&key="
+ Constants.API_KEY + "&orig=%1$s&dir=%2$s";
private final static int MAX_ATTEMPTS = 5;
private Exception mException;
private List<Route> mRoutes;
@Override
protected RealTimeDepartures doInBackground(Params... paramsArray) {
// Always expect one param
Params params = paramsArray[0];
mRoutes = params.origin.getRoutesForDestination(params.destination);
if (!isCancelled()) {
return getDeparturesFromNetwork(params, 0);
} else {
return null;
}
}
private RealTimeDepartures getDeparturesFromNetwork(Params params,
int attemptNumber) {
String xml = null;
try {
HttpUriRequest request = new HttpGet(String.format(ETD_URL,
params.origin.abbreviation, mRoutes.get(0).getDirection()));
EtdContentHandler handler = new EtdContentHandler(params.origin,
params.destination, mRoutes);
if (isCancelled()) {
return null;
}
HttpResponse response = NetworkUtils.executeWithRecovery(request);
if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
throw new IOException("Server returned "
+ response.getStatusLine().toString());
}
StringWriter writer = new StringWriter();
IOUtils.copy(response.getEntity().getContent(), writer, "UTF-8");
xml = writer.toString();
if (xml.length() == 0) {
throw new IOException("Server returned blank xml document");
}
Xml.parse(xml, handler);
final RealTimeDepartures realTimeDepartures = handler
.getRealTimeDepartures();
return realTimeDepartures;
} catch (MalformedURLException e) {
throw new RuntimeException(e);
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e);
} catch (IOException e) {
if (attemptNumber < MAX_ATTEMPTS - 1) {
try {
Log.w(Constants.TAG,
"Attempt to contact server failed... retrying in 3s",
e);
Thread.sleep(3000);
} catch (InterruptedException interrupt) {
// Ignore... just go on to next attempt
}
return getDeparturesFromNetwork(params, attemptNumber + 1);
} else {
mException = new Exception("Could not contact BART system", e);
return null;
}
} catch (SAXException e) {
mException = new Exception(
"Could not understand response from BART system: " + xml, e);
return null;
}
}
public static class Params {
public Params(Station origin, Station destination) {
super();
this.origin = origin;
this.destination = destination;
}
private Station origin;
private Station destination;
public Station getOrigin() {
return origin;
}
public Station getDestination() {
return destination;
}
}
@Override
protected void onPostExecute(RealTimeDepartures result) {
if (result != null) {
onResult(result);
} else {
onError(mException);
}
}
public abstract void onResult(RealTimeDepartures result);
public abstract void onError(Exception exception);
}