119 lines
3.3 KiB
Java
119 lines
3.3 KiB
Java
package com.dougkeen.bart.networktasks;
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import java.io.IOException;
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import java.io.StringWriter;
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import java.io.UnsupportedEncodingException;
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import java.net.MalformedURLException;
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import org.apache.commons.io.IOUtils;
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import org.apache.http.HttpResponse;
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import org.apache.http.HttpStatus;
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import org.apache.http.client.methods.HttpGet;
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import org.apache.http.client.methods.HttpUriRequest;
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import org.xml.sax.SAXException;
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import android.os.AsyncTask;
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import android.util.Log;
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import android.util.Xml;
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import com.dougkeen.bart.model.Constants;
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import com.dougkeen.bart.model.ScheduleInformation;
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import com.dougkeen.bart.model.StationPair;
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public abstract class GetScheduleInformationTask extends
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AsyncTask<StationPair, Integer, ScheduleInformation> {
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private final static String SCHED_URL = "http://api.bart.gov/api/sched.aspx?cmd=depart&key="
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+ Constants.API_KEY + "&orig=%1$s&dest=%2$s&b=1&a=4";
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private final static int MAX_ATTEMPTS = 5;
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private Exception mException;
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@Override
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protected ScheduleInformation doInBackground(StationPair... paramsArray) {
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// Always expect one param
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StationPair params = paramsArray[0];
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if (!isCancelled()) {
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return getScheduleFromNetwork(params, 0);
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} else {
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return null;
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}
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}
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private ScheduleInformation getScheduleFromNetwork(StationPair params,
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int attemptNumber) {
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String xml = null;
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try {
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String url = String.format(SCHED_URL,
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params.getOrigin().abbreviation,
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params.getDestination().abbreviation);
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HttpUriRequest request = new HttpGet(url);
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if (isCancelled()) {
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return null;
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}
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ScheduleContentHandler handler = new ScheduleContentHandler(
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params.getOrigin(), params.getDestination());
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HttpResponse response = NetworkUtils.executeWithRecovery(request);
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if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
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throw new IOException("Server returned "
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+ response.getStatusLine().toString());
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}
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StringWriter writer = new StringWriter();
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IOUtils.copy(response.getEntity().getContent(), writer, "UTF-8");
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xml = writer.toString();
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if (xml.length() == 0) {
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throw new IOException("Server returned blank xml document");
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}
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Xml.parse(xml, handler);
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final ScheduleInformation schedule = handler.getSchedule();
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return schedule;
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} catch (MalformedURLException e) {
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throw new RuntimeException(e);
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} catch (UnsupportedEncodingException e) {
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throw new RuntimeException(e);
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} catch (IOException e) {
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if (attemptNumber < MAX_ATTEMPTS - 1) {
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try {
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Log.w(Constants.TAG,
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"Attempt to contact server failed... retrying in 3s",
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e);
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Thread.sleep(3000);
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} catch (InterruptedException interrupt) {
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// Ignore... just go on to next attempt
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}
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return getScheduleFromNetwork(params, attemptNumber + 1);
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} else {
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mException = new Exception("Could not contact BART system", e);
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return null;
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}
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} catch (SAXException e) {
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mException = new Exception(
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"Could not understand response from BART system: " + xml, e);
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return null;
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}
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}
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@Override
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protected void onPostExecute(ScheduleInformation result) {
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if (result != null) {
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onResult(result);
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} else {
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onError(mException);
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}
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}
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public abstract void onResult(ScheduleInformation result);
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public abstract void onError(Exception exception);
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}
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