Java tutorial
/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package io.melle.carboncycle; import com.google.android.gms.common.ConnectionResult; import com.google.android.gms.common.GooglePlayServicesClient; import com.google.android.gms.common.GooglePlayServicesUtil; import com.google.android.gms.location.LocationClient; import com.google.android.gms.location.LocationListener; import com.google.android.gms.location.LocationRequest; import com.google.android.gms.maps.CameraUpdateFactory; import com.google.android.gms.maps.GoogleMap; import com.google.android.gms.maps.SupportMapFragment; import com.google.android.gms.maps.model.BitmapDescriptorFactory; import com.google.android.gms.maps.model.CameraPosition; import com.google.android.gms.maps.model.LatLng; import com.google.android.gms.maps.model.MarkerOptions; import android.content.IntentSender; import android.location.Address; import android.location.Geocoder; import android.location.Location; import android.os.AsyncTask; import android.os.Build; import android.os.Bundle; import android.annotation.SuppressLint; import android.app.Activity; import android.app.Dialog; import android.content.Context; import android.content.Intent; import android.content.SharedPreferences; import android.support.v4.app.DialogFragment; import android.support.v4.app.FragmentActivity; import android.util.Log; import android.view.View; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; import java.io.IOException; import java.util.List; import java.util.Locale; import io.melle.carboncycle.LocationService; /** * This the app's main Activity. It provides buttons for requesting the various features of the * app, displays the current location, the current address, and the status of the location client * and updating services. * * {@link #getLocation} gets the current location using the Location Services getLastLocation() * function. {@link #getAddress} calls geocoding to get a street address for the current location. * {@link #startUpdates} sends a request to Location Services to send periodic location updates to * the Activity. * {@link #stopUpdates} cancels previous periodic update requests. * * The update interval is hard-coded to be 5 seconds. */ public class MapsActivity extends FragmentActivity implements LocationListener, GooglePlayServicesClient.ConnectionCallbacks, GooglePlayServicesClient.OnConnectionFailedListener { private GoogleMap mMap; // A request to connect to Location Services private LocationRequest mLocationRequest; // Stores the current instantiation of the location client in this object private LocationClient mLocationClient; // Global variable to hold the current location Location mCurrentLocation; // Handles to UI widgets private TextView mLatLng; private TextView mAddress; private ProgressBar mActivityIndicator; private TextView mConnectionState; private TextView mConnectionStatus; // Handle to SharedPreferences for this app SharedPreferences mPrefs; // Handle to a SharedPreferences editor SharedPreferences.Editor mEditor; /* * Note if updates have been turned on. Starts out as "false"; is set to "true" in the * method handleRequestSuccess of LocationUpdateReceiver. * */ boolean mUpdatesRequested = false; /* * Initialize the Activity */ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_maps); // Get handles to the UI view objects mLatLng = (TextView) findViewById(R.id.lat_lng); mAddress = (TextView) findViewById(R.id.address); mActivityIndicator = (ProgressBar) findViewById(R.id.address_progress); mConnectionState = (TextView) findViewById(R.id.text_connection_state); mConnectionStatus = (TextView) findViewById(R.id.text_connection_status); // Create a new global location parameters object mLocationRequest = LocationRequest.create(); /* * Set the update interval */ mLocationRequest.setInterval(LocationUtils.UPDATE_INTERVAL_IN_MILLISECONDS); // Use high accuracy mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY); // Set the interval ceiling to one minute mLocationRequest.setFastestInterval(LocationUtils.FAST_INTERVAL_CEILING_IN_MILLISECONDS); // Note that location updates are off until the user turns them on mUpdatesRequested = false; // Open Shared Preferences mPrefs = getSharedPreferences(LocationUtils.SHARED_PREFERENCES, Context.MODE_PRIVATE); // Get an editor mEditor = mPrefs.edit(); /* * Create a new location client, using the enclosing class to * handle callbacks. */ mLocationClient = new LocationClient(this, this, this); setUpMapIfNeeded(); } /* * Called when the Activity is no longer visible at all. * Stop updates and disconnect. */ @Override public void onStop() { // If the client is connected if (mLocationClient.isConnected()) { stopPeriodicUpdates(); } // After disconnect() is called, the client is considered "dead". mLocationClient.disconnect(); super.onStop(); } /* * Called when the Activity is going into the background. * Parts of the UI may be visible, but the Activity is inactive. */ @Override public void onPause() { // Save the current setting for updates mEditor.putBoolean(LocationUtils.KEY_UPDATES_REQUESTED, mUpdatesRequested); mEditor.commit(); super.onPause(); } /* * Called when the Activity is restarted, even before it becomes visible. */ @Override public void onStart() { super.onStart(); /* * Connect the client. Don't re-start any requests here; * instead, wait for onResume() */ mLocationClient.connect(); } /* * Called when the system detects that this Activity is now visible. */ @Override public void onResume() { super.onResume(); // If the app already has a setting for getting location updates, get it if (mPrefs.contains(LocationUtils.KEY_UPDATES_REQUESTED)) { mUpdatesRequested = mPrefs.getBoolean(LocationUtils.KEY_UPDATES_REQUESTED, false); // Otherwise, turn off location updates until requested } else { mEditor.putBoolean(LocationUtils.KEY_UPDATES_REQUESTED, false); mEditor.commit(); } } /* * Handle results returned to this Activity by other Activities started with * startActivityForResult(). In particular, the method onConnectionFailed() in * LocationUpdateRemover and LocationUpdateRequester may call startResolutionForResult() to * start an Activity that handles Google Play services problems. The result of this * call returns here, to onActivityResult. */ @Override protected void onActivityResult(int requestCode, int resultCode, Intent intent) { // Choose what to do based on the request code switch (requestCode) { // If the request code matches the code sent in onConnectionFailed case LocationUtils.CONNECTION_FAILURE_RESOLUTION_REQUEST: switch (resultCode) { // If Google Play services resolved the problem case Activity.RESULT_OK: // Log the result Log.d(LocationUtils.APPTAG, getString(R.string.resolved)); // Display the result mConnectionState.setText(R.string.connected); mConnectionStatus.setText(R.string.resolved); break; // If any other result was returned by Google Play services default: // Log the result Log.d(LocationUtils.APPTAG, getString(R.string.no_resolution)); // Display the result mConnectionState.setText(R.string.disconnected); mConnectionStatus.setText(R.string.no_resolution); break; } // If any other request code was received default: // Report that this Activity received an unknown requestCode Log.d(LocationUtils.APPTAG, getString(R.string.unknown_activity_request_code, requestCode)); break; } } /** * Verify that Google Play services is available before making a request. * * @return true if Google Play services is available, otherwise false */ private boolean servicesConnected() { // Check that Google Play services is available int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this); // If Google Play services is available if (ConnectionResult.SUCCESS == resultCode) { // In debug mode, log the status Log.d(LocationUtils.APPTAG, getString(R.string.play_services_available)); // Continue return true; // Google Play services was not available for some reason } else { // Display an error dialog Dialog dialog = GooglePlayServicesUtil.getErrorDialog(resultCode, this, 0); if (dialog != null) { ErrorDialogFragment errorFragment = new ErrorDialogFragment(); errorFragment.setDialog(dialog); errorFragment.show(getSupportFragmentManager(), LocationUtils.APPTAG); } return false; } } /** * Invoked by the "Get Location" button. * * Calls getLastLocation() to get the current location * * @param v The view object associated with this method, in this case a Button. */ public void getLocation(View v) { // If Google Play Services is available if (servicesConnected()) { // Get the current location Location currentLocation = mLocationClient.getLastLocation(); // Display the current location in the UI mLatLng.setText(LocationUtils.getLatLng(this, currentLocation)); } } /** * Invoked by the "Get Address" button. * Get the address of the current location, using reverse geocoding. This only works if * a geocoding service is available. * * @param v The view object associated with this method, in this case a Button. */ // For Eclipse with ADT, suppress warnings about Geocoder.isPresent() @SuppressLint("NewApi") public void getAddress(View v) { // In Gingerbread and later, use Geocoder.isPresent() to see if a geocoder is available. if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD && !Geocoder.isPresent()) { // No geocoder is present. Issue an error message Toast.makeText(this, R.string.no_geocoder_available, Toast.LENGTH_LONG).show(); return; } if (servicesConnected()) { // Get the current location Location currentLocation = mLocationClient.getLastLocation(); // Turn the indefinite activity indicator on mActivityIndicator.setVisibility(View.VISIBLE); // Start the background task (new MapsActivity.GetAddressTask(this)).execute(currentLocation); } } /** * Invoked by the "Start Updates" button * Sends a request to start location updates * * @param v The view object associated with this method, in this case a Button. */ public void startUpdates(View v) { mUpdatesRequested = true; if (servicesConnected()) { startPeriodicUpdates(); } } /** * Invoked by the "Stop Updates" button * Sends a request to remove location updates * request them. * * @param v The view object associated with this method, in this case a Button. */ public void stopUpdates(View v) { mUpdatesRequested = false; if (servicesConnected()) { stopPeriodicUpdates(); } } /* * Called by Location Services when the request to connect the * client finishes successfully. At this point, you can * request the current location or start periodic updates */ @Override public void onConnected(Bundle bundle) { mConnectionStatus.setText(R.string.connected); if (mUpdatesRequested) { startPeriodicUpdates(); } } /* * Called by Location Services if the connection to the * location client drops because of an error. */ @Override public void onDisconnected() { mConnectionStatus.setText(R.string.disconnected); } /* * Called by Location Services if the attempt to * Location Services fails. */ @Override public void onConnectionFailed(ConnectionResult connectionResult) { /* * Google Play services can resolve some errors it detects. * If the error has a resolution, try sending an Intent to * start a Google Play services activity that can resolve * error. */ if (connectionResult.hasResolution()) { try { // Start an Activity that tries to resolve the error connectionResult.startResolutionForResult(this, LocationUtils.CONNECTION_FAILURE_RESOLUTION_REQUEST); /* * Thrown if Google Play services canceled the original * PendingIntent */ } catch (IntentSender.SendIntentException e) { // Log the error e.printStackTrace(); } } else { // If no resolution is available, display a dialog to the user with the error. showErrorDialog(connectionResult.getErrorCode()); } } /** * Report location updates to the UI. * * @param location The updated location. */ @Override public void onLocationChanged(Location location) { LocationUtils.CURRENTLOCATION = new LatLng(location.getLatitude(), location.getLongitude()); // Report to the UI that the location was updated mConnectionStatus.setText(R.string.location_updated); // In the UI, set the latitude and longitude to the value received mLatLng.setText(LocationUtils.getLatLng(this, location)); drawMarker(location); } /** * In response to a request to start updates, send a request * to Location Services */ private void startPeriodicUpdates() { Intent i = new Intent(getApplicationContext(), LocationService.class); Bundle extras = new Bundle(); extras.putString(LocationService.FIREBASE_REF, "https://carboncycle.firebaseio.com/location/guru.json"); extras.putLong(LocationService.LOCATION_POLL_INTERVAL, 15000); i.putExtras(extras); startService(i); mLocationClient.requestLocationUpdates(mLocationRequest, this); mConnectionState.setText(R.string.location_requested); } /** * In response to a request to stop updates, send a request to * Location Services */ private void stopPeriodicUpdates() { Intent i = new Intent(getApplicationContext(), LocationService.class); mLocationClient.removeLocationUpdates(this); mConnectionState.setText(R.string.location_updates_stopped); stopService(i); } /** * An AsyncTask that calls getFromLocation() in the background. * The class uses the following generic types: * Location - A {@link android.location.Location} object containing the current location, * passed as the input parameter to doInBackground() * Void - indicates that progress units are not used by this subclass * String - An address passed to onPostExecute() */ protected class GetAddressTask extends AsyncTask<Location, Void, String> { // Store the context passed to the AsyncTask when the system instantiates it. Context localContext; // Constructor called by the system to instantiate the task public GetAddressTask(Context context) { // Required by the semantics of AsyncTask super(); // Set a Context for the background task localContext = context; } /** * Get a geocoding service instance, pass latitude and longitude to it, format the returned * address, and return the address to the UI thread. */ @Override protected String doInBackground(Location... params) { /* * Get a new geocoding service instance, set for localized addresses. This example uses * android.location.Geocoder, but other geocoders that conform to address standards * can also be used. */ Geocoder geocoder = new Geocoder(localContext, Locale.getDefault()); // Get the current location from the input parameter list Location location = params[0]; // Create a list to contain the result address List<Address> addresses = null; // Try to get an address for the current location. Catch IO or network problems. try { /* * Call the synchronous getFromLocation() method with the latitude and * longitude of the current location. Return at most 1 address. */ addresses = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1); // Catch network or other I/O problems. } catch (IOException exception1) { // Log an error and return an error message Log.e(LocationUtils.APPTAG, getString(R.string.IO_Exception_getFromLocation)); // print the stack trace exception1.printStackTrace(); // Return an error message return (getString(R.string.IO_Exception_getFromLocation)); // Catch incorrect latitude or longitude values } catch (IllegalArgumentException exception2) { // Construct a message containing the invalid arguments String errorString = getString(R.string.illegal_argument_exception, location.getLatitude(), location.getLongitude()); // Log the error and print the stack trace Log.e(LocationUtils.APPTAG, errorString); exception2.printStackTrace(); // return errorString; } // If the reverse geocode returned an address if (addresses != null && addresses.size() > 0) { // Get the first address Address address = addresses.get(0); // Format the first line of address String addressText = getString(R.string.address_output_string, // If there's a street address, add it address.getMaxAddressLineIndex() > 0 ? address.getAddressLine(0) : "", // Locality is usually a city address.getLocality() // The country of the address //address.getCountryName() ); // Return the text return addressText; // If there aren't any addresses, post a message } else { return getString(R.string.no_address_found); } } /** * A method that's called once doInBackground() completes. Set the text of the * UI element that displays the address. This method runs on the UI thread. */ @Override protected void onPostExecute(String address) { // Turn off the progress bar mActivityIndicator.setVisibility(View.GONE); // Set the address in the UI mAddress.setText(address); } } /** * Show a dialog returned by Google Play services for the * connection error code * * @param errorCode An error code returned from onConnectionFailed */ private void showErrorDialog(int errorCode) { // Get the error dialog from Google Play services Dialog errorDialog = GooglePlayServicesUtil.getErrorDialog(errorCode, this, LocationUtils.CONNECTION_FAILURE_RESOLUTION_REQUEST); // If Google Play services can provide an error dialog if (errorDialog != null) { // Create a new DialogFragment in which to show the error dialog ErrorDialogFragment errorFragment = new ErrorDialogFragment(); // Set the dialog in the DialogFragment errorFragment.setDialog(errorDialog); // Show the error dialog in the DialogFragment errorFragment.show(getSupportFragmentManager(), LocationUtils.APPTAG); } } /** * Define a DialogFragment to display the error dialog generated in * showErrorDialog. */ public static class ErrorDialogFragment extends DialogFragment { // Global field to contain the error dialog private Dialog mDialog; /** * Default constructor. Sets the dialog field to null */ public ErrorDialogFragment() { super(); mDialog = null; } /** * Set the dialog to display * * @param dialog An error dialog */ public void setDialog(Dialog dialog) { mDialog = dialog; } /* * This method must return a Dialog to the DialogFragment. */ @Override public Dialog onCreateDialog(Bundle savedInstanceState) { return mDialog; } } private void setUpMapIfNeeded() { // Do a null check to confirm that we have not already instantiated the map. if (mMap == null) { // Try to obtain the map from the SupportMapFragment. mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap(); // Check if we were successful in obtaining the map. if (mMap != null) { setUpMap(); } } } /** * This is where we can add markers or lines, add listeners or move the camera. In this case, we * just add a marker near Africa. * <p> * This should only be called once and when we are sure that {@link #mMap} is not null. */ private void setUpMap() { mMap.setMyLocationEnabled(true); mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL); mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(LocationUtils.PHILLY, 15)); } private void drawMarker(Location location) { mMap.clear(); LatLng currentPosition = new LatLng(location.getLatitude(), location.getLongitude()); mMap.addMarker(new MarkerOptions().position(currentPosition) .snippet("Lat:" + location.getLatitude() + "Lng:" + location.getLongitude()) .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)).title("ME")); CameraPosition camPosition = new CameraPosition.Builder().target(currentPosition) // Sets the center of the map to Mountain View .zoom(17) // Sets the zoom .bearing(location.getBearing()) // Sets the orientation of the camera to east .tilt(30) // Sets the tilt of the camera to 30 degrees .build(); // Creates a CameraPosition from the builder mMap.animateCamera(CameraUpdateFactory.newCameraPosition(camPosition)); } CameraPosition cameraPosition = new CameraPosition.Builder().target(LocationUtils.CURRENTLOCATION) // Sets the center of the map to Mountain View .zoom(17) // Sets the zoom .bearing(90) // Sets the orientation of the camera to east .tilt(30) // Sets the tilt of the camera to 30 degrees .build(); // Creates a CameraPosition from the builder }