Java tutorial
package edu.mit.mobile.android.locast.data; /* * Copyright (C) 2010 MIT Mobile Experience Lab * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.location.Location; import android.net.Uri; import com.beoui.geocell.GeocellUtils; import com.beoui.geocell.model.Point; import com.google.android.maps.GeoPoint; import edu.mit.mobile.android.locast.data.JsonSyncableItem.SyncCustom; import edu.mit.mobile.android.locast.data.JsonSyncableItem.SyncItem; /** * A helper for things that are locatable. Implement Locatable.Columns to use. * @author steve * */ public abstract class Locatable { /** * implement this in order to inherit columns needed for becoming locatable. * @author steve * */ public static interface Columns { public static final String _LATITUDE = "lat", _LONGITUDE = "lon", _GEOCELL = "geocell"; }; public static final String SERVER_QUERY_PARAMETER = "dist"; public static final String SELECTION_LAT_LON = "abs(" + Columns._LATITUDE + " - ?) < 1 and abs(" + Columns._LONGITUDE + " - ?) < 1"; public static Uri toGeoUri(Cursor c) { if (c.isNull(c.getColumnIndex(Columns._LATITUDE)) || c.isNull(c.getColumnIndex(Columns._LONGITUDE))) { return null; } return Uri.parse("geo:" + c.getDouble(c.getColumnIndex(Columns._LATITUDE)) + "," + c.getDouble(c.getColumnIndex(Columns._LONGITUDE))); } /** * Makes a URI that queries the locatable item by distance. * * @param contentUri the Locatable content URI to build upon. Must be a dir, not an item. * @param location center point * @param distance distance in meters * @return */ public static Uri toDistanceSearchUri(Uri contentUri, Location location, double distance) { return contentUri.buildUpon().appendQueryParameter(SERVER_QUERY_PARAMETER, location.getLongitude() + "," + location.getLatitude() + "," + distance).build(); } /** * Makes a URI that queries the locatable item by distance. * * @param contentUri * the GeoPoint content URI to build upon. Must be a dir, not an item. * @param location * center point * @param distance * distance in meters * @return */ public static Uri toDistanceSearchUri(Uri contentUri, GeoPoint location, double distance) { return contentUri.buildUpon() .appendQueryParameter(SERVER_QUERY_PARAMETER, location.getLongitudeE6() / 1E6f + "," + location.getLatitudeE6() / 1E6f + "," + distance) .build(); } /** * Get the latitude/longitude from the row currently selected in the cursor. Requires Locatable.Columns._LATITUDE and Locatable.Columns._LONGITUDE to be selected. * @param c * @return */ public static Location toLocation(Cursor c) { final int lat_idx = c.getColumnIndex(Columns._LATITUDE); final int lon_idx = c.getColumnIndex(Columns._LONGITUDE); if (c.isNull(lat_idx) || c.isNull(lon_idx)) { return null; } final Location l = new Location("internal"); l.setLatitude(c.getDouble(lat_idx)); l.setLongitude(c.getDouble(lon_idx)); return l; } /** * Get the latitude/longitude from the row currently selected in the cursor. Requires Locatable.Columns._LATITUDE and Locatable.Columns._LONGITUDE to be selected. * @param c * @return */ public static Location toLocation(Cursor c, int latColumn, int lonColumn) { if (c.isNull(latColumn) || c.isNull(lonColumn)) { return null; } final Location l = new Location("internal"); l.setLatitude(c.getDouble(latColumn)); l.setLongitude(c.getDouble(lonColumn)); return l; } /** * Fills the result array with the current location. * * @param c cursor pointing to row to get location of * @param result output array. Must have 2 or more elements. Latitude is in index 0. */ public static void toLocationArray(Cursor c, int latColumn, int lonColumn, double[] result) { if (c.isNull(latColumn) || c.isNull(lonColumn)) { return; } result[0] = c.getDouble(latColumn); result[1] = c.getDouble(lonColumn); } /** * Adds the appropriate {@link Columns#_LATITUDE}, {@link Columns#_LONGITUDE} columns to the given {@link ContentValues} for the given location. * @param cv * @param location * @return the same {@link ContentValues} that was passed in. */ public static ContentValues toContentValues(ContentValues cv, GeoPoint location) { cv.put(Columns._LATITUDE, location.getLatitudeE6() / 1E6d); cv.put(Columns._LONGITUDE, location.getLongitudeE6() / 1E6d); return cv; } public static final SyncMap SYNC_MAP = new SyncMap(); static { SYNC_MAP.put("_location", new SyncCustom("location", SyncItem.FLAG_OPTIONAL | SyncItem.SYNC_BOTH) { @Override public JSONArray toJSON(Context context, Uri localItem, Cursor c, String lProp) throws JSONException { final int latCol = c.getColumnIndex(Columns._LATITUDE); final int lonCol = c.getColumnIndex(Columns._LONGITUDE); if (c.isNull(latCol) || c.isNull(lonCol)) { return null; } final JSONArray coords = new JSONArray(); coords.put(c.getDouble(lonCol)); coords.put(c.getDouble(latCol)); return coords; } @Override public ContentValues fromJSON(Context context, Uri localItem, JSONObject item, String lProp) throws JSONException { final JSONArray ja = item.getJSONArray(remoteKey); final ContentValues cv = new ContentValues(); final double lon = ja.getDouble(0); final double lat = ja.getDouble(1); cv.put(Columns._LONGITUDE, lon); cv.put(Columns._LATITUDE, lat); cv.put(Columns._GEOCELL, GeocellUtils.compute(new Point(lat, lon), 13)); return cv; } }); } }