android - 如何在应用程序从最近的任务中被杀死后重新启动服务

Question

我已经创建了一个服务来定期获取设备的当前位置。我希望该服务在后台运行，即使该应用程序已从最近打开的应用程序中清除。目前该服务仅在后台运行，直到应用程序出现在最近打开的应用程序中，但当应用程序被刷掉(或以其他方式终止)时立即停止。我已经尝试了堆栈溢出中可用的各种帮助，但我无法解决这个问题。请帮忙。这是我的服务代码。

package com.packr.services;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ServiceInfo;
import android.location.Location;
import android.os.Bundle;
import android.os.IBinder;
import android.os.SystemClock;
import android.support.annotation.Nullable;
import android.util.Log;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;

import java.text.DateFormat;
import java.util.Date;

/**
 * Created by Arindam on 11-Dec-15.
 */
public class LocationService extends Service implements
        GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener {
    protected static final String TAG = "packrMATE";
    /**
     * The desired interval for location updates. Inexact. Updates may be more or less frequent.
     */
    public static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10000;

    /**
     * The fastest rate for active location updates. Exact. Updates will never be more frequent
     * than this value.
     */
    public static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS =
            UPDATE_INTERVAL_IN_MILLISECONDS / 2;

    // Keys for storing activity state in the Bundle.
    protected final static String REQUESTING_LOCATION_UPDATES_KEY = "requesting-location-updates-key";
    protected final static String LOCATION_KEY = "location-key";
    protected final static String LAST_UPDATED_TIME_STRING_KEY = "last-updated-time-string-key";

    /**
     * Provides the entry point to Google Play services.
     */
    protected GoogleApiClient mGoogleApiClient;

    /**
     * Stores parameters for requests to the FusedLocationProviderApi.
     */
    protected LocationRequest mLocationRequest;

    /**
     * Represents a geographical location.
     */
    protected Location mCurrentLocation;

    /**
     * Tracks the status of the location updates request. Value changes when the user presses the
     * Start Updates and Stop Updates buttons.
     */
    protected Boolean mRequestingLocationUpdates;

    /**
     * Time when the location was updated represented as a String.
     */
    protected String mLastUpdateTime;

    @Override
    public void onCreate() {
        Log.d(TAG,"Service started");
        super.onCreate();
        mRequestingLocationUpdates = false;
        mLastUpdateTime = "";

        // Kick off the process of building a GoogleApiClient and requesting the LocationServices
        // API.
        buildGoogleApiClient();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d(TAG,"Service fucking started");
        mGoogleApiClient.connect();
        if (mGoogleApiClient.isConnected()) {
            startLocationUpdates();
        }
        return Service.START_STICKY;

    }

    @Override
    public void onDestroy() {
        mGoogleApiClient.disconnect();
        super.onDestroy();
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onConnected(Bundle bundle) {
        Log.i(TAG, "Connected to GoogleApiClient");

        // If the initial location was never previously requested, we use
        // FusedLocationApi.getLastLocation() to get it. If it was previously requested, we store
        // its value in the Bundle and check for it in onCreate(). We
        // do not request it again unless the user specifically requests location updates by pressing
        // the Start Updates button.
        //
        // Because we cache the value of the initial location in the Bundle, it means that if the
        // user launches the activity,
        // moves to a new location, and then changes the device orientation, the original location
        // is displayed as the activity is re-created.
        if (mCurrentLocation == null) {
            mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
            mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
            Toast.makeText(getApplicationContext(),"Hello Babe",Toast.LENGTH_SHORT).show();
        }

        // If the user presses the Start Updates button before GoogleApiClient connects, we set
        // mRequestingLocationUpdates to true (see startUpdatesButtonHandler()). Here, we check
        // the value of mRequestingLocationUpdates and if it is true, we start location updates.
            startLocationUpdates();
    }

    @Override
    public void onConnectionSuspended(int i) {
        // The connection to Google Play services was lost for some reason. We call connect() to
        // attempt to re-establish the connection.
        Log.i(TAG, "Connection suspended");
        mGoogleApiClient.connect();
    }

    @Override
    public void onLocationChanged(Location location) {
        mCurrentLocation = location;
        mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
        Toast.makeText(this, String.valueOf(location.getLatitude() + " "+ String.valueOf(location.getLongitude())),
                Toast.LENGTH_SHORT).show();
        Log.e(TAG,"fuck man location found");
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        // Refer to the javadoc for ConnectionResult to see what error codes might be returned in
        // onConnectionFailed.
        Log.i(TAG, "Connection failed: ConnectionResult.getErrorCode() = " + connectionResult.getErrorCode());
    }

    protected synchronized void buildGoogleApiClient() {
        Log.i(TAG, "Building GoogleApiClient");
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        createLocationRequest();

    }
    /**
     * Sets up the location request. Android has two location request settings:
     * {@code ACCESS_COARSE_LOCATION} and {@code ACCESS_FINE_LOCATION}. These settings control
     * the accuracy of the current location. This sample uses ACCESS_FINE_LOCATION, as defined in
     * the AndroidManifest.xml.
     * <p/>
     * When the ACCESS_FINE_LOCATION setting is specified, combined with a fast update
     * interval (5 seconds), the Fused Location Provider API returns location updates that are
     * accurate to within a few feet.
     * <p/>
     * These settings are appropriate for mapping applications that show real-time location
     * updates.
     */
    protected void createLocationRequest() {
        mLocationRequest = new LocationRequest();

        // Sets the desired interval for active location updates. This interval is
        // inexact. You may not receive updates at all if no location sources are available, or
        // you may receive them slower than requested. You may also receive updates faster than
        // requested if other applications are requesting location at a faster interval.
        mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);

        // Sets the fastest rate for active location updates. This interval is exact, and your
        // application will never receive updates faster than this value.
        mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS);

        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    }

    /**
     * Requests location updates from the FusedLocationApi.
     */
    protected void startLocationUpdates() {
        // The final argument to {@code requestLocationUpdates()} is a LocationListener
        // (http://developer.android.com/reference/com/google/android/gms/location/LocationListener.html).
        LocationServices.FusedLocationApi.requestLocationUpdates(
                mGoogleApiClient, mLocationRequest, this);
    }
    /**
     * Removes location updates from the FusedLocationApi.
     */
    protected void stopLocationUpdates() {
        // It is a good practice to remove location requests when the activity is in a paused or
        // stopped state. Doing so helps battery performance and is especially
        // recommended in applications that request frequent location updates.

        // The final argument to {@code requestLocationUpdates()} is a LocationListener
        // (http://developer.android.com/reference/com/google/android/gms/location/LocationListener.html).
        LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
    }
    @Override
    public void onTaskRemoved(Intent rootIntent) {
        Log.e("FLAGX : ", ServiceInfo.FLAG_STOP_WITH_TASK + "");
        Intent restartServiceIntent = new Intent(getApplicationContext(),
                this.getClass());
        restartServiceIntent.setPackage(getPackageName());

        PendingIntent restartServicePendingIntent = PendingIntent.getService(
                getApplicationContext(), 1, restartServiceIntent,
                PendingIntent.FLAG_ONE_SHOT);
        AlarmManager alarmService = (AlarmManager) getApplicationContext()
                .getSystemService(Context.ALARM_SERVICE);
        alarmService.set(AlarmManager.ELAPSED_REALTIME,
                SystemClock.elapsedRealtime() + 1000,
                restartServicePendingIntent);

        super.onTaskRemoved(rootIntent);
    }
}

Answer 1

在您的服务中覆盖 onTaskRemoved() 并使用警报管理器再次启动服务。下面是我们应用程序中的代码，它执行相同的操作并且运行良好:

@Override
public void onTaskRemoved(Intent rootIntent) {
    super.onTaskRemoved(rootIntent);

    Log.d(TAG, "TASK REMOVED");

    PendingIntent service = PendingIntent.getService(
            getApplicationContext(),
            1001,
            new Intent(getApplicationContext(), MyService.class),
            PendingIntent.FLAG_ONE_SHOT);

    AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
    alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, 1000, service);
}  

即使服务因内存不足(或出于任何原因)而被终止，您也可能希望定期发送位置，因此我建议您处理 uncaughtException 以在 N 秒后重新启动它。这就是我们在完美运行的应用程序中所做的:

private Thread.UncaughtExceptionHandler defaultUEH;
private Thread.UncaughtExceptionHandler uncaughtExceptionHandler = new Thread.UncaughtExceptionHandler() {

    @Override
    public void uncaughtException(Thread thread, Throwable ex) {
        Log.d(TAG, "Uncaught exception start!");
        ex.printStackTrace();

        //Same as done in onTaskRemoved()
        PendingIntent service = PendingIntent.getService(
                getApplicationContext(),
                1001,
                new Intent(getApplicationContext(), MyService.class),
                PendingIntent.FLAG_ONE_SHOT);

        AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, 1000, service);
        System.exit(2);
        }
    };

注意:我认为并且我记得我在 Kitkat 上验证过 START_STICKY 不适用于 Kitkat 和更高的 API 级别。请自行验证。

更多:
当您定期进行 loc 发送时，您可能需要考虑深度 sleep 模式。要让事情在深度 sleep 中工作，请使用 WakefulBroadcastReceiver结合 AlarmManager。看看我的另一篇文章How to use http in deep sleep mode .

更新:
如果用户从“设置”中“强制停止”应用程序，则此解决方案不起作用(实际上不需要起作用)。这实际上很好，因为如果用户自己想停止应用程序，重新启动服务并不是一个好方法。所以，没关系。