Android AlarmManager or Service?

2019-08-29 08:11发布

问题:

I have an application, that has a main.java file that sets up an alarm to call a recurring service. However when I close the application the service is no longer called for some weird reason. So I was reading around what I should be doing for my application (basically what I want is something like Twicca, where the twitter app continues to run even if you close it from your "task manager"). And it looks like what I need to do is deploy my entire application as a service, so that it will keep running indefinitely unless the system closes it. Is this what I should be doing? Or is there a more appropriate way to do this?

I was reading around SO and found a question which linked me to this - http://android-codes-examples.blogspot.com/2011/11/running-service-in-background-on.html?m=1 - is that what I should be doing? It seems that in that example basically the user closes the application but it continues to run as a service in the background, correct?

For reference here are my files:

MainActivity.java

https://gist.github.com/4414275

RepeatingAlarm.java

https://gist.github.com/4414277

I have it set up correctly in my manifest since the alarm is behaving as it should be here is that file to.

https://gist.github.com/4414285

回答1:

You'll have to use a service. There is a complete example inside the ApiDemos - the names are AlarmService_Service and AlarmService. I will post the code here for you:

    /*
 * Copyright (C) 2007 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 com.example.android.apis.app;

// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.SystemClock;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;


/**
 * This demonstrates how you can schedule an alarm that causes a service to
 * be started.  This is useful when you want to schedule alarms that initiate
 * long-running operations, such as retrieving recent e-mails.
 */
public class AlarmService extends Activity {
    private PendingIntent mAlarmSender;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Create an IntentSender that will launch our service, to be scheduled
        // with the alarm manager.
        mAlarmSender = PendingIntent.getService(AlarmService.this,
                0, new Intent(AlarmService.this, AlarmService_Service.class), 0);

        setContentView(R.layout.alarm_service);

        // Watch for button clicks.
        Button button = (Button)findViewById(R.id.start_alarm);
        button.setOnClickListener(mStartAlarmListener);
        button = (Button)findViewById(R.id.stop_alarm);
        button.setOnClickListener(mStopAlarmListener);
    }

    private OnClickListener mStartAlarmListener = new OnClickListener() {
        public void onClick(View v) {
            // We want the alarm to go off 30 seconds from now.
            long firstTime = SystemClock.elapsedRealtime();

            // Schedule the alarm!
            AlarmManager am = (AlarmManager)getSystemService(ALARM_SERVICE);
            am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
                            firstTime, 30*1000, mAlarmSender);

            // Tell the user about what we did.
            Toast.makeText(AlarmService.this, R.string.repeating_scheduled,
                    Toast.LENGTH_LONG).show();
        }
    };

    private OnClickListener mStopAlarmListener = new OnClickListener() {
        public void onClick(View v) {
            // And cancel the alarm.
            AlarmManager am = (AlarmManager)getSystemService(ALARM_SERVICE);
            am.cancel(mAlarmSender);

            // Tell the user about what we did.
            Toast.makeText(AlarmService.this, R.string.repeating_unscheduled,
                    Toast.LENGTH_LONG).show();

        }
    };
}

And the service:

/*
 * Copyright (C) 2007 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 com.example.android.apis.app;

// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.os.Parcel;
import android.os.RemoteException;
import android.widget.Toast;

/**
 * This is an example of implementing an application service that will run in
 * response to an alarm, allowing us to move long duration work out of an
 * intent receiver.
 * 
 * @see AlarmService
 * @see AlarmService_Alarm
 */
public class AlarmService_Service extends Service {
    NotificationManager mNM;

    @Override
    public void onCreate() {
        mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);

        // show the icon in the status bar
        showNotification();

        // Start up the thread running the service.  Note that we create a
        // separate thread because the service normally runs in the process's
        // main thread, which we don't want to block.
        Thread thr = new Thread(null, mTask, "AlarmService_Service");
        thr.start();
    }

    @Override
    public void onDestroy() {
        // Cancel the notification -- we use the same ID that we had used to start it
        mNM.cancel(R.string.alarm_service_started);

        // Tell the user we stopped.
        Toast.makeText(this, R.string.alarm_service_finished, Toast.LENGTH_SHORT).show();
    }

    /**
     * The function that runs in our worker thread
     */
    Runnable mTask = new Runnable() {
        public void run() {
            // Normally we would do some work here...  for our sample, we will
            // just sleep for 30 seconds.
            long endTime = System.currentTimeMillis() + 15*1000;
            while (System.currentTimeMillis() < endTime) {
                synchronized (mBinder) {
                    try {
                        mBinder.wait(endTime - System.currentTimeMillis());
                    } catch (Exception e) {
                    }
                }
            }

            // Done with our work...  stop the service!
            AlarmService_Service.this.stopSelf();
        }
    };

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

    /**
     * Show a notification while this service is running.
     */
    private void showNotification() {
        // In this sample, we'll use the same text for the ticker and the expanded notification
        CharSequence text = getText(R.string.alarm_service_started);

        // Set the icon, scrolling text and timestamp
        Notification notification = new Notification(R.drawable.stat_sample, text,
                System.currentTimeMillis());

        // The PendingIntent to launch our activity if the user selects this notification
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, AlarmService.class), 0);

        // Set the info for the views that show in the notification panel.
        notification.setLatestEventInfo(this, getText(R.string.alarm_service_label),
                       text, contentIntent);

        // Send the notification.
        // We use a layout id because it is a unique number.  We use it later to cancel.
        mNM.notify(R.string.alarm_service_started, notification);
    }

    /**
     * This is the object that receives interactions from clients.  See RemoteService
     * for a more complete example.
     */
    private final IBinder mBinder = new Binder() {
        @Override
        protected boolean onTransact(int code, Parcel data, Parcel reply,
                int flags) throws RemoteException {
            return super.onTransact(code, data, reply, flags);
        }
    };
}