Android Open Source - campus Place Details Loader

• Back to Map/Campus  ↑

From Project

Back to project page campus.

License

The source code is released under:

GNU General Public License

Java Source Code

package lecho.app.campus.loader;
//from www.j ava2  s  .co m
import java.util.ArrayList;
import java.util.List;

import lecho.app.campus.dao.DaoSession;
import lecho.app.campus.dao.Faculty;
import lecho.app.campus.dao.FacultyDao;
import lecho.app.campus.dao.Place;
import lecho.app.campus.dao.PlaceDao;
import lecho.app.campus.dao.PlaceUnitDao;
import lecho.app.campus.dao.Unit;
import lecho.app.campus.dao.UnitDao;
import lecho.app.campus.utils.Config;
import lecho.app.campus.utils.DatabaseHelper;
import lecho.app.campus.utils.PlaceDetails;
import lecho.app.campus.utils.UnitsGroup;
import android.content.Context;
import android.support.v4.content.AsyncTaskLoader;
import android.util.Log;

/**
 * Loads Place details from database, name, symbol, faculties etc. Loader doesn't watch for changes in database, there's
 * no need for that in this app.
 * 
 * Implementation based on sample from android sdk documentation.
 * 
 * @author Lecho
 * 
 */
public class PlaceDetailsLoader extends AsyncTaskLoader<PlaceDetails> {
  private static final String TAG = "PlaceDetailsLoader";
  private static final String QUERY_UNITS_BY_PLACE_ORDER_BY_FACULTY = "left join " + PlaceUnitDao.TABLENAME
      + " PU on PU." + PlaceUnitDao.Properties.UnitId.columnName + "=T." + UnitDao.Properties.Id.columnName
      + " left join " + FacultyDao.TABLENAME + " F on F." + FacultyDao.Properties.Id.columnName + "=T."
      + UnitDao.Properties.FacultyId.columnName + " where PU." + PlaceUnitDao.Properties.PlaceId.columnName
      + "=? order by ifnull(F." + FacultyDao.Properties.ShortName.columnName + ",'zzz') asc, T."
      + UnitDao.Properties.Name.columnName + " asc";

  private Long mPlaceId;
  private DaoSession mDaoSession;
  private PlaceDetails mData;

  public PlaceDetailsLoader(Context context, Long placeId) {
    super(context);
    mPlaceId = placeId;
  }

  @Override
  public PlaceDetails loadInBackground() {
    if (Config.DEBUG) {
      Log.d(TAG, "Loading place details");
    }
    mDaoSession = DatabaseHelper.getDaoSession(getContext());
    PlaceDao placeDao = mDaoSession.getPlaceDao();
    UnitDao unitDao = mDaoSession.getUnitDao();
    Place place = placeDao.load(mPlaceId);
    if (null == place) {
      Log.e(TAG, "Could not load place details - null place for id: " + mPlaceId);
      return null;
    }
    String[] args = new String[] { Long.toString(place.getId()) };
    List<Unit> units = unitDao.queryDeep(QUERY_UNITS_BY_PLACE_ORDER_BY_FACULTY, args);
    List<UnitsGroup> unitsGroups = groupUnits(units);
    PlaceDetails placeDetails = new PlaceDetails(place, unitsGroups);
    return placeDetails;
  }

  /**
   * Groups units by faculty name
   * @param units
   * @return
   */
  private List<UnitsGroup> groupUnits(List<Unit> units) {
    List<UnitsGroup> unitsGroups = new ArrayList<UnitsGroup>();
    if (units.isEmpty()) {
      return unitsGroups;
    }
    Faculty currentFaculty = units.get(0).getFaculty();
    String currentFacultyName;
    if (null != currentFaculty) {
      currentFacultyName = currentFaculty.getShortName();
    } else {
      currentFacultyName = "";
    }
    List<Unit> group = new ArrayList<Unit>();
    for (Unit unit : units) {
      String newFacultyName;
      Faculty newFaculty = unit.getFaculty();
      if (null != newFaculty) {
        newFacultyName = newFaculty.getShortName();
      } else {
        newFacultyName = "";
      }
      if (!currentFacultyName.equals(newFacultyName)) {
        // if new unit has different faculty - start new group.
        unitsGroups.add(new UnitsGroup(currentFaculty, group));
        currentFaculty = newFaculty;
        currentFacultyName = newFacultyName;
        group = new ArrayList<Unit>();
      }
      group.add(unit);
    }
    // Add last group if it's not empty.
    if (!group.isEmpty()) {
      unitsGroups.add(new UnitsGroup(currentFaculty, group));
    }
    return unitsGroups;
  }

  /**
   * Called when there is new data to deliver to the client. The super class will take care of delivering it; the
   * implementation here just adds a little more logic.
   */
  @Override
  public void deliverResult(PlaceDetails data) {
    if (Config.DEBUG) {
      Log.d(TAG, "Delivering place details");
    }
    if (isReset()) {
      // An async query came in while the loader is stopped. We
      // don't need the result.
      if (data != null) {
        onReleaseResources(data);
      }
    }
    PlaceDetails oldData = mData;
    mData = data;

    if (isStarted()) {
      // If the Loader is currently started, we can immediately
      // deliver its results.
      super.deliverResult(data);
    }

    // At this point we can release the resources associated with
    // 'oldData' if needed; now that the new result is delivered we
    // know that it is no longer in use.
    if (oldData != null && oldData != data) {
      onReleaseResources(oldData);
    }
  }

  /**
   * Handles a request to start the Loader.
   */
  @Override
  protected void onStartLoading() {
    if (mData != null) {
      // If we currently have a result available, deliver it
      // immediately.
      deliverResult(mData);
    } else {
      forceLoad();
    }
  }

  /**
   * Handles a request to stop the Loader.
   */
  @Override
  protected void onStopLoading() {
    // Attempt to cancel the current load task if possible.
    cancelLoad();
  }

  /**
   * Handles a request to cancel a load.
   */
  @Override
  public void onCanceled(PlaceDetails data) {
    super.onCanceled(data);

    // At this point we can release the resources associated with 'apps'
    // if needed.
    onReleaseResources(data);
  }

  /**
   * Handles a request to completely reset the Loader.
   */
  @Override
  protected void onReset() {
    super.onReset();

    // Ensure the loader is stopped
    onStopLoading();

    // At this point we can release the resources associated with 'apps'
    // if needed.
    if (mData != null) {
      onReleaseResources(mData);
      mData = null;
    }
  }

  /**
   * Helper function to take care of releasing resources associated with an actively loaded data set.
   */
  protected void onReleaseResources(PlaceDetails data) {
  }
}

Java Source Code List

• Back to Map/Campus  ↑