Java tutorial
/* * GeoSolutions map - Digital field mapping on Android based devices * Copyright (C) 2013 GeoSolutions (www.geo-solutions.it) * * 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 3 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, see <http://www.gnu.org/licenses/>. */ package it.geosolutions.android.map.loaders; import it.geosolutions.android.map.database.SpatialDataSourceHandler; import it.geosolutions.android.map.model.Feature; import it.geosolutions.android.map.model.FeaturePolygonQueryResult; import it.geosolutions.android.map.model.FeaturePolygonTaskQuery; import it.geosolutions.android.map.utils.Coordinates_Query; import java.util.ArrayList; import java.util.List; import jsqlite.Exception; import android.content.Context; import android.support.v4.content.AsyncTaskLoader; import android.util.Log; import eu.geopaparazzi.spatialite.database.spatial.core.SpatialVectorTable; /** * Async query task to query layers. Updates an adapter with the results from a * query A query to the task is a "List of Lists of Maps", implemented with a * bundle of bundles The main bundle contains is name->list of features feature * contains name->value bundles * * @author Jacopo Pianigiani (jacopo.pianigiani85@gmail.com) */ public class FeaturePolygonLoader extends AsyncTaskLoader<List<FeaturePolygonQueryResult>> { int features_loaded = 0; private List<FeaturePolygonQueryResult> mData; private FeaturePolygonTaskQuery[] queryQueue; // private FeaturePolygonObserver mObserver; private static int MAX_FEATURES = 10; /** * Constructor for FeaturePolygonLoader class * @param ctx * @param queryQueue */ public FeaturePolygonLoader(Context ctx, FeaturePolygonTaskQuery[] queryQueue) { // Loaders may be used across multiple Activities (assuming they aren't // bound to the LoaderManager), so NEVER hold a reference to the context // directly. Doing so will cause you to leak an entire Activity's context. // The superclass constructor will store a reference to the Application // Context instead, and can be retrieved with a call to getContext(). super(ctx); this.queryQueue = queryQueue; } protected void doInBackground(FeaturePolygonTaskQuery[] queryQueue, List<FeaturePolygonQueryResult> data) { Log.d("FEATURE_Polygon_TASK", "Polygon Task Launched"); //process all queries for (FeaturePolygonTaskQuery query : queryQueue) { if (!processQuery(query, data)) { return; } } return; } /** * Process a single <FeaturePolygonQuery> * @param query * @param data the result will be added to this array */ private boolean processQuery(FeaturePolygonTaskQuery query, List<FeaturePolygonQueryResult> data) { SpatialDataSourceHandler handler = query.getHandler(); SpatialVectorTable table = query.getTable(); String tableName = query.getTable().getName(); // check visibility before adding the table // AdvancedStyle s = sm.getStyle(tableName); // if ( !StyleUtils.isVisible(s, zoomLevel) ) { // onProgressUpdate(0); // continue; // } ArrayList<Coordinates_Query> polygon_points = query.getPolygonPoints(); Integer start = query.getStart(); Integer limit = query.getLimit(); if (Log.isLoggable("FEATURE_Polygon_TASK", Log.DEBUG)) { // Log check to avoid // string creation Log.d("FEATURE_Polygon_TASK", "starting query for table " + tableName); } // this is empty to skip geometries that returns errors ArrayList<Feature> features = new ArrayList<Feature>(); /*try { features = handler.intersectionToPolygon("4326", table, polygon_points, start, limit); } catch (Exception e) { Log.e("FEATURE_Polygon_TASK", "unable to retrive data for table'" + tableName + "\'.Error:" + e.getLocalizedMessage()); // TODO now simply skip, do better work }*/ // add features FeaturePolygonQueryResult result = new FeaturePolygonQueryResult(); result.setLayerName(tableName); result.setFeatures(features); Log.v("FEATURE_Polygon_TASK", features.size() + " items found for table " + tableName); features_loaded += features.size(); // publishProgress(result); data.add(result); return true; } /* * (non-Javadoc) * @see android.support.v4.content.AsyncTaskLoader#loadInBackground() */ @Override public List<FeaturePolygonQueryResult> loadInBackground() { List<FeaturePolygonQueryResult> data = new ArrayList<FeaturePolygonQueryResult>(); // TODO: Perform the query here and add the results to 'data'. doInBackground(queryQueue, data); return data; } // ********************************************************/ // ** Deliver the results to the registered listener **/ // ********************************************************/ @Override public void deliverResult(List<FeaturePolygonQueryResult> data) { if (isReset()) { // The Loader has been reset; ignore the result and invalidate the data. releaseResources(data); return; } // Hold a reference to the old data so it doesn't get garbage collected. // We must protect it until the new data has been delivered. List<FeaturePolygonQueryResult> oldData = mData; mData = data; if (isStarted()) { // If the Loader is in a started state, deliver the results to the // client. The superclass method does this for us. super.deliverResult(data); } // Invalidate the old data as we don't need it any more. if (oldData != null && oldData != data) { releaseResources(oldData); } } // ********************************************************/ // ** Implement the Loaders state-dependent behavior **/ // ********************************************************/ @Override protected void onStartLoading() { if (mData != null) { // Deliver any previously loaded data immediately. deliverResult(mData); } // Begin monitoring the underlying data source. // if (mObserver == null) { // mObserver = new SampleObserver(); // // TODO: register the observer // } if (takeContentChanged() || mData == null) { // When the observer detects a change, it should call onContentChanged() // on the Loader, which will cause the next call to takeContentChanged() // to return true. If this is ever the case (or if the current data is // null), we force a new load. forceLoad(); } } /* * (non-Javadoc) * @see android.support.v4.content.Loader#onStopLoading() */ @Override protected void onStopLoading() { cancelLoad(); } /* * (non-Javadoc) * @see android.support.v4.content.Loader#onReset() */ @Override protected void onReset() { onStopLoading(); if (mData != null) { releaseResources(mData); mData = null; } // if(mObserver !=null){ // //TODO unregister the observer // moObserver=null; // // } } /* * (non-Javadoc) * @see android.support.v4.content.AsyncTaskLoader#onCanceled(java.lang.Object) */ @Override public void onCanceled(List<FeaturePolygonQueryResult> data) { // TODO Auto-generated method stub super.onCanceled(data); releaseResources(data); } /** * @param data */ private void releaseResources(List<FeaturePolygonQueryResult> data) { // release resource if needed } }