Java tutorial
/* * Copyright (C) 2016 Basile * * This file is part of Mobility Rate Calculator. * * Mobility Rate Calculator 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. * * Foobar 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 Foobar. If not, see <http://www.gnu.org/licenses/>. */ package ch.pec0ra.mobilityratecalculator; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.net.ConnectivityManager; import android.net.NetworkInfo; import android.net.Uri; import com.google.common.io.CharStreams; import org.json.JSONException; import org.json.JSONObject; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.URL; class DistanceCalculator { private final String from; private final String to; private final boolean isTwoWay; private final Context context; public DistanceCalculator(String from, String to, boolean isTwoWay, Context context) { this.from = from; this.to = to; this.isTwoWay = isTwoWay; this.context = context; } public Itinerary calculate() { if (!checkConnection()) { return new Itinerary(context.getString(R.string.connexion_error)); } try { URL url = new URL(buildImageUrl()); Bitmap bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream()); String ret = downloadUrl(buildDistancesUrl()); return new Itinerary(new JSONObject(ret), isTwoWay, bmp); } catch (Exception e) { e.printStackTrace(); return new Itinerary(context.getString(R.string.connexion_error)); } } private String buildDistancesUrl() { String ret = MapsDistances.BASE_DISTANCES_URL; ret += MapsDistances.ORIGINS + Uri.encode(from); ret += MapsDistances.AND; ret += MapsDistances.DESTINATIONS + Uri.encode(to); ret += MapsDistances.AND; ret += MapsDistances.KEY + MapsDistances.distancesKey; return ret; } private String buildDirectionsUrl() { String ret = MapsDistances.BASE_DIRECTIONS_URL; ret += MapsDistances.ORIGIN + Uri.encode(from); ret += MapsDistances.AND; ret += MapsDistances.DESTINATION + Uri.encode(to); ret += MapsDistances.AND; ret += MapsDistances.KEY + MapsDistances.directionsKey; return ret; } private String buildImageUrl() throws IOException, JSONException { String polyLines = getOverviewPolylines(); String ret = MapsDistances.BASE_MAP_URL; ret += MapsDistances.SIZE_OPTION + MapsDistances.WIDTH + MapsDistances.X + MapsDistances.HEIGHT; ret += MapsDistances.AND; ret += MapsDistances.MAP_TYPE; ret += MapsDistances.AND; ret += MapsDistances.MARKERS_A + Uri.encode(from); ret += MapsDistances.AND; ret += MapsDistances.MARKERS_B + Uri.encode(to); ret += MapsDistances.AND; ret += MapsDistances.PATH + polyLines; ret += MapsDistances.AND; ret += MapsDistances.KEY + MapsDistances.staticMapKey; return ret; } private String getOverviewPolylines() throws IOException, JSONException { JSONObject object = new JSONObject(downloadUrl(buildDirectionsUrl())); String status = object.getString("status"); if (!status.equals("OK")) { throw new RuntimeException(); } JSONObject route = object.getJSONArray("routes").getJSONObject(0); return route.getJSONObject("overview_polyline").getString("points"); } public class Itinerary { public final Bitmap image; public final int distance; public final String from; public final String to; public final boolean isTwoWay; public boolean hasError = false; public String errorMessage = null; public Itinerary(String errorMessage) { image = null; distance = 0; from = null; to = null; isTwoWay = false; hasError = true; this.errorMessage = errorMessage; } public Itinerary(JSONObject jsonObject, boolean isTwoWay, Bitmap image) throws JSONException { this.isTwoWay = isTwoWay; String status = jsonObject.getString("status"); if (!status.equals("OK")) { if (status.equals("INVALID_REQUEST")) { this.image = null; distance = 0; from = null; to = null; hasError = true; this.errorMessage = context.getString(R.string.invalid_request); return; } else { throw new RuntimeException(); } } from = jsonObject.getJSONArray("origin_addresses").getString(0); to = jsonObject.getJSONArray("destination_addresses").getString(0); JSONObject row = jsonObject.getJSONArray("rows").getJSONObject(0); JSONObject element = row.getJSONArray("elements").getJSONObject(0); status = element.getString("status"); if (status.equals("ZERO_RESULTS")) { this.image = null; distance = 0; hasError = true; errorMessage = context.getString(R.string.no_result_found); } else if (status.equals("OK")) { distance = element.getJSONObject("distance").getInt("value"); this.image = image; } else { throw new RuntimeException(); } } } private boolean checkConnection() { ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo networkInfo = connMgr.getActiveNetworkInfo(); return networkInfo != null && networkInfo.isConnected(); } // Given a URL, establishes an HttpUrlConnection and retrieves // the web page content as a InputStream, which it returns as // a string. private String downloadUrl(String myurl) throws IOException { InputStream is = null; try { URL url = new URL(myurl); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setReadTimeout(10000 /* milliseconds */); conn.setConnectTimeout(15000 /* milliseconds */); conn.setRequestMethod("GET"); conn.setDoInput(true); // Starts the query conn.connect(); conn.getResponseCode(); is = conn.getInputStream(); String responseAsString = CharStreams.toString(new InputStreamReader(is)); return responseAsString; // Makes sure that the InputStream is closed after the app is // finished using it. } finally { if (is != null) { is.close(); } } } }