问题
So I've spent the past few weeks working on my Android App and looking into the best way of implementing what I need to do, but still can't quite get it right.. Any/all help is greatly appreciated, as I am still getting the hang of things..
Task:
(Assuming the "Location"/GPS Setting is currently off), I need to have my App constantly be listening for the "Location" Setting to be turned ON.. At this point, simply start an Activity.
Ideas:
These are all the different ways I think it could possibly work:
LocationListener using "onProviderEnabled"
GpsStatusListener using "onGpsStatusChanged" with "GPS_EVENT_STARTED"
GpsProvider requiresSatellite (to determine if it starts), or somehow use the GpsProvider's "AVAILABLE" Constant/int
SettingInjectorService using "ACTION_SERVICE_INTENT" (and/or) "ACTION_INJECTED_SETTING_CHANGED" with "onGetEnabled" or "isEnabled"
Settings.Secure using "LOCATION_MODE" != "LOCATION_MODE_OFF"
a ContentObserver/ContentResolver
Intent getAction (...)
An "if/else" of some kind
Questions:
Any kind of advice or answers for any of the following questions are very much appreciated..
Which of the Ideas above would be the best way of accomplishing the Task? The simpler the better, but most importantly it needs to be listening at all times, and respond instantly when the Location Setting is turned On.
For whichever one of the Ideas above works best, how would I implement it? (For example, would I need a BroadcastListener? or a Service? and how would it all piece together?
I truly appreciate any advice or help that you can provide me with.. I'm still getting the hang of all this, but confident enough to do it, and eager to publish my first App.. So thank you, it means a lot and will greatly help me along.
EDIT:
OK So here's what I've got so far...
Heres my Receiver:
MyReceiver.Java
public class MyReceiver extends BroadcastReceiver {
private final static String TAG = "LocationProviderChanged";
boolean isGpsEnabled;
boolean isNetworkEnabled;
public MyReceiver() {
// EMPTY
// MyReceiver Close Bracket
}
// START OF onReceive
@Override
public void onReceive(Context context, Intent intent) {
// PRIMARY RECEIVER
if (intent.getAction().matches("android.location.PROVIDERS_CHANGED")) {
Log.i(TAG, "Location Providers Changed");
LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
isGpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
Toast.makeText(context, "GPS Enabled: " + isGpsEnabled + " Network Location Enabled: " + isNetworkEnabled, Toast.LENGTH_LONG).show();
// START DIALOG ACTIVITY
if (isGpsEnabled || isNetworkEnabled) {
Intent runDialogActivity = new Intent(context, DialogActivity.class);
context.startActivity(runDialogActivity);
}
}
// BOOT COMPLETED (REPLICA OF PRIMARY RECEIVER CODE FOR WHEN BOOT_COMPLETED)
if (intent.getAction().matches("android.intent.action.BOOT_COMPLETED")) {
Log.i(TAG, "Location Providers Changed Boot");
LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
isGpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
Toast.makeText(context, "GPS Enabled Boot: " + isGpsEnabled + " Network Location Enabled Boot: " + isNetworkEnabled, Toast.LENGTH_LONG).show();
// START DIALOG ACTIVITY
if (isGpsEnabled || isNetworkEnabled) {
Intent runDialogActivity = new Intent(context, DialogActivity.class);
context.startActivity(runDialogActivity);
}
}
// onReceive CLOSE BRACKET
}
// CLOSE OF FULL CLASS
}
And heres what the Manifest looks like:
Manifest.XML
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.ender.projects.receivertest">
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<application
android:allowBackup="true"
android:fullBackupContent="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".DialogActivity">
</activity>
<receiver
android:name=".MyReceiver"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="android.location.PROVIDERS_CHANGED" />
<action android:name="android.intent.action.BOOT_COMPLETED" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
</application>
</manifest>
Aside from these files, I have the following files:MainActivity.Java and DialogActivity.Java, both with Layout files,activity_main.xml and activity_dialog.xml to match with them.
So if I understand correctly, when the user downloads the App and opens it, my MainActivity.Java and corresponding layout will launch. But I am only going to use this simply as a preferences screen. So once they open the App for the first time, the Broadcast Receiver should automatically start listening for the LOCATION setting to be turned on, correct? I also want the Broadcast Listener to remain listening, even after it receives the initial Broadcast (so that my onReceive still fires if they turn the LOCATION setting off, and then later they turn it ON again..
So (A) How does my code look thus far?
and (B) To accomplish what I just described, what would need to be added?
and (C) Running it throws this error when I turn the LOCATION setting ON.
..How can I fix it?:java.lang.RuntimeException: Unable to start receiver com.bryce.projects.servicesthreadsetc.MyReceiver: android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
Thanks again for all the help!
回答1:
Since you don't need to actually get a Location, the best implementation for your needs would be a BroadcastReceiver.
This is the best option because you wouldn't need to have a Service running at all times (resulting in extra batter drain), and you would be able to start your Activity from the BroadcastReceiver.
With the intent filter and BroadcastReceiver, your app will be started by the OS whenever the Location setting has changed (enabled or disabled), and in the case that it is enabled, you can start your Activity from the BroadcastReceiver.
First add the intent filter, which will be captured when the OS sends out the implicit Intent that the setting has changed.
<receiver
android:name=".LocationProviderChangedReceiver"
android:exported="false" >
<intent-filter>
<action android:name="android.location.PROVIDERS_CHANGED" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</receiver>
Note that for this to work on Android Oreo and above, you'll need to register the broadcast receiver at runtime, see here: https://developer.android.com/guide/components/broadcasts#context-registered-receivers
Then, in LocationProviderChangedReceiver.java, your implementation would be something like this:
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.location.LocationManager;
import android.util.Log;
import android.widget.Toast;
public class LocationProviderChangedReceiver extends BroadcastReceiver {
private final static String TAG = "LocationProviderChanged";
boolean isGpsEnabled;
boolean isNetworkEnabled;
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().matches("android.location.PROVIDERS_CHANGED"))
{
Log.i(TAG, "Location Providers changed");
LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
isGpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
//Start your Activity if location was enabled:
if (isGpsEnabled || isNetworkEnabled) {
Intent i = new Intent(context, YourActivity.class);
context.startActivity(i);
}
}
}
}
Edit
Updated solution with Kotlin and registering receiver at runtime for Android 9.
The BroadcastReceiver class in Kotlin:
class LocationProviderChangedReceiver : BroadcastReceiver() {
internal var isGpsEnabled: Boolean = false
internal var isNetworkEnabled: Boolean = false
override fun onReceive(context: Context, intent: Intent) {
intent.action?.let { act ->
if (act.matches("android.location.PROVIDERS_CHANGED".toRegex())) {
val locationManager = context.getSystemService(Context.LOCATION_SERVICE) as LocationManager
isGpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)
isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)
Log.i(TAG, "Location Providers changed, is GPS Enabled: " + isGpsEnabled)
//Start your Activity if location was enabled:
if (isGpsEnabled || isNetworkEnabled) {
val i = Intent(context, YourActivity::class.java)
context.startActivity(i)
}
}
}
}
companion object {
private val TAG = "LocationProviderChanged"
}
}
Register at runtime, for example in onCreate() of your app's MainActivity:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val br: BroadcastReceiver = LocationProviderChangedReceiver()
val filter = IntentFilter(LocationManager.PROVIDERS_CHANGED_ACTION)
registerReceiver(br, filter)
}
回答2:
Here is a solution using dynamic registration:
In your fragment or activity's onResume() method, listen to changes in LocationManager.PROVIDERS_CHANGED_ACTION
IntentFilter filter = new IntentFilter(LocationManager.PROVIDERS_CHANGED_ACTION);
filter.addAction(Intent.ACTION_PROVIDER_CHANGED);
mActivity.registerReceiver(gpsSwitchStateReceiver, filter);
Here is a code sample for the gpsSwitchStateReceiver object:
private BroadcastReceiver gpsSwitchStateReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if (LocationManager.PROVIDERS_CHANGED_ACTION.equals(intent.getAction())) {
// Make an action or refresh an already managed state.
LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
boolean isGpsEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
boolean isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (isGpsEnabled || isNetworkEnabled) {
Log.i(this.getClass().getName(), "gpsSwitchStateReceiver.onReceive() location is enabled : isGpsEnabled = " + isGpsEnabled + " isNetworkEnabled = " + isNetworkEnabled);
} else {
Log.w(this.getClass().getName(), "gpsSwitchStateReceiver.onReceive() location disabled ");
}
}
}
};
In your onPause() method, unregister the receiver
mActivity.unregisterReceiver(gpsSwitchStateReceiver);
回答3:
LocationListeners's onProvideEnabled() method will work instantly. When you call this remember if you are doing LocationManager.removeUpdates() in between onProviderEnabled() won't work.
And this is pretty much simple when you are reading locations from Location API's of Android. You don't need the broadcast receivers listening and communication further
But when you are using FusedLocationProviderClient from google API and if you use LocationListener's onProviderEnabled and onProviderDisabled methods you will be having two services running in parallel, checking for the provider changes. So using BroadcastReceiver is better
来源：https://stackoverflow.com/questions/36325088/how-to-listen-for-location-setting-being-turned-on-android-app