Android Open Source - lightbox-android-webservices Location Helper

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License

The source code is released under:
Apache License
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Java Source Code

/**
 * Copyright (c) 2012 Lightbox//  w w w  . jav  a  2s . c o  m
 *
 * 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 com.lightbox.android.location;

import java.io.IOException;
import java.lang.ref.WeakReference;
import java.util.List;

import android.content.Context;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;

import com.lightbox.android.utils.debug.DebugLog;

/** 
 * LocationHelper 
 * @author Fabien Devos & Nilesh Patel
 */
public class LocationHelper implements android.location.LocationListener {
  /** Used to tag logs */
  //@SuppressWarnings("unused")
  private static final String TAG = "LocationHelper";

  private static long LOCATION_VALIDITY_DURATION_MS = 2 * 60 * 1000; // 2 min 
  
  private WeakReference<LocationListener> mListenerWeak;
  private LocationManager mLocationManager;
  
  private final static int LOCATION_TIMEOUT_MS = 30 * 1000; // 30 seconds
  private Handler mHandler;
  
  /**
   * Constructor.
   */
  public LocationHelper(Context context, LocationListener listener) {
    mListenerWeak = new WeakReference<LocationListener>(listener);
    mLocationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
  }
  
  private boolean isGpsLocationProviderEnabled() {
    try {
          return mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
        } catch (Exception e) {
          DebugLog.d(TAG, e.getMessage());
        }
    
    return false;
  }
  
  private boolean isNetworkLocationProviderEnabled() {
    try {
          return mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
        } catch (Exception e) {
          DebugLog.d(TAG, e.getMessage());
        }
    
    return false;
  }
  
  //----------------------------------------------
  // Public API
  
  /** Start retrieving location, caching it for a few minutes. */
  public void startRetrievingLocation() {    
    Location location = getLastKnownLocation();
    // If the last known location is recent enough, just return it, else request location updates
    if (location != null && (System.currentTimeMillis() - location.getTime()) <= LOCATION_VALIDITY_DURATION_MS) {
      LocationListener listener = mListenerWeak.get();
      if (listener != null) {
        listener.onFoundLocation(location);
      }
    } else {
      // Don't start listeners if no provider is enabled
          if (!isGpsLocationProviderEnabled() && !isNetworkLocationProviderEnabled()) {
            LocationListener listener = mListenerWeak.get();
        if (listener != null) {
          listener.onUnableToFindLocation(new IllegalStateException("No provider available"));
        }
              return;
          }
                  
          if (isGpsLocationProviderEnabled()) {
              mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
          }
          if (isNetworkLocationProviderEnabled()) {
            mLocationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, this);
          }
          
          mHandler = new Handler();
          mHandler.postDelayed(new GetLastLocation(this), LOCATION_TIMEOUT_MS);
    }
  }
  
  public void stopRetrievingLocation() {
    mLocationManager.removeUpdates(this);
  }
  
  /** Get last known location even if this location is old. */
  public Location getLastKnownLocation() {    
    Location netLoc = null;
        Location gpsLoc = null;
        if (isGpsLocationProviderEnabled()) {
            gpsLoc = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        }
        if (isNetworkLocationProviderEnabled()) {
            netLoc = mLocationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
        }

        // If there are both values use the latest one
        if (gpsLoc != null && netLoc != null){
            if (gpsLoc.getTime() > netLoc.getTime()) {
                return gpsLoc;
            } else {
                return netLoc;
            }
        }

        if (gpsLoc != null) {
          return gpsLoc;
        }
        if (netLoc != null) {
            return netLoc;
        }
      return null;
  }
  
  /** Get address from location */
  public static String getReverseGeocodedAddress(Context context, Location location) {
    String addrStr = "";
    
    Geocoder geocoder = new Geocoder(context);
    try {
      List<Address> addresses = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
      StringBuilder addressStrBuilder = new StringBuilder();
      if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);
        for (int i = 0; i < address.getMaxAddressLineIndex() && i < 1; i++) {
          addressStrBuilder.append(address.getAddressLine(i) + " ");
        }
        addrStr = addressStrBuilder.toString();
      }
    } catch (IOException e) {
      Log.w(TAG,"Unable to retrieve reverse geocoded address.", e);
    }
    return addrStr;
  }
  
  public static String getReverseGeocodedApproxArea(Context context, Location location) {
    return getReverseGeocodedApproxArea(context, location.getLongitude(), location.getLatitude());
  }
  
  public static String getReverseGeocodedApproxArea(Context context, double longitude, double latitude) {
    String area = null;
    
    Geocoder geocoder = new Geocoder(context);
    try {
      List<Address> addresses = geocoder.getFromLocation(latitude, longitude, 3);
      int numAddresses = addresses.size();
      for (int i = 0; i < numAddresses; i++) {
        Address address = addresses.get(i);
        
        if (area == null) {
          area = address.getSubLocality();
        }
        if (area == null) {
          area = address.getLocality();
        }
        if (area == null) {
          area = address.getSubAdminArea();
        }
        if (area == null) {
          area = address.getAdminArea();
        }
        
        if (area != null) {
          return area;
        }
      }
    } catch (IOException e) {
      Log.w(TAG,"Unable to retrieve reverse geocoded address.", e);
    }
    return "";
  }
  
  //----------------------------------------------
  // Location Listener

  @Override
  public void onLocationChanged(Location location) {
    // Only update once
    mLocationManager.removeUpdates(this);
    
    LocationListener listener = mListenerWeak.get();
    if (listener != null) {
      listener.onFoundLocation(location);
    }
  }

  @Override
  public void onProviderDisabled(String provider) {
    if (!isGpsLocationProviderEnabled() && !isNetworkLocationProviderEnabled()) { //Only if both are no longer available
      mLocationManager.removeUpdates(this);
      
      LocationListener listener = mListenerWeak.get();
      if (listener != null) {
        listener.onUnableToFindLocation(new IOException("Unable to find location, provider disabled: " + provider));
      }
    }
  }

  @Override
  public void onProviderEnabled(String provider) {
    // Nothing to do
  }

  @Override
  public void onStatusChanged(String provider, int status, Bundle extras) {
    if (status == LocationProvider.OUT_OF_SERVICE || status == LocationProvider.TEMPORARILY_UNAVAILABLE) {
      if (!isGpsLocationProviderEnabled() && !isNetworkLocationProviderEnabled()) { //Only if both are no longer available
        // Only update once
        mLocationManager.removeUpdates(this);
        
        LocationListener listener = mListenerWeak.get();
        if (listener != null) {
          listener.onUnableToFindLocation(new IOException("Unable to find location, provider unavailable or out of service: " + provider));
        }
      }
    }
  }
  
  private static class GetLastLocation implements Runnable {
    WeakReference<LocationHelper> mRef;

    public GetLastLocation(LocationHelper helper) {
      mRef = new WeakReference<LocationHelper>(helper);
    }

    @Override
    public void run() {
      LocationHelper helper = mRef.get();

      if (helper != null) {

        helper.mLocationManager.removeUpdates(helper);

        Location location = helper.getLastKnownLocation();
        LocationListener listener = helper.mListenerWeak.get();
        if (listener != null) {
          if (location != null) {
            listener.onFoundLocation(location);
          } else {
            listener.onUnableToFindLocation(new Exception("No last known location"));
          }
        }
      }
    }
  }
  
}
Java Source Code List
