ForegroundService.java

/*
 * Copyright (C) 2009 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;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

// 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;

/**
 * This is an example of implementing an application service that can
 * run in the "foreground".  It shows how to code this to work well by using
 * the improved Android 2.0 APIs when available and otherwise falling back
 * to the original APIs.  Yes: you can take this exact code, compile it
 * against the Android 2.0 SDK, and it will against everything down to
 * Android 1.0.
 */
public class ForegroundService extends Service {
    static final String ACTION_FOREGROUND = "com.example.android.apis.FOREGROUND";
    static final String ACTION_BACKGROUND = "com.example.android.apis.BACKGROUND";
    
    private static final Class[] mStartForegroundSignature = new Class[] {
        int.class, Notification.class};
    private static final Class[] mStopForegroundSignature = new Class[] {
        boolean.class};
    
    private NotificationManager mNM;
    private Method mStartForeground;
    private Method mStopForeground;
    private Object[] mStartForegroundArgs = new Object[2];
    private Object[] mStopForegroundArgs = new Object[1];
    
    @Override
    public void onCreate() {
        mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
        try {
            mStartForeground = getClass().getMethod("startForeground",
                    mStartForegroundSignature);
            mStopForeground = getClass().getMethod("stopForeground",
                    mStopForegroundSignature);
        } catch (NoSuchMethodException e) {
            // Running on an older platform.
            mStartForeground = mStopForeground = null;
        }
    }

    // This is the old onStart method that will be called on the pre-2.0
    // platform.  On 2.0 or later we override onStartCommand() so this
    // method will not be called.
    @Override
    public void onStart(Intent intent, int startId) {
        handleCommand(intent);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        handleCommand(intent);
        // We want this service to continue running until it is explicitly
        // stopped, so return sticky.
        return START_STICKY;
    }

    void handleCommand(Intent intent) {
        if (ACTION_FOREGROUND.equals(intent.getAction())) {
            // In this sample, we'll use the same text for the ticker and the expanded notification
            CharSequence text = getText(R.string.foreground_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, ForegroundServiceController.class), 0);

            // Set the info for the views that show in the notification panel.
            notification.setLatestEventInfo(this, getText(R.string.local_service_label),
                           text, contentIntent);
            
            startForegroundCompat(R.string.foreground_service_started, notification);
            
        } else if (ACTION_BACKGROUND.equals(intent.getAction())) {
            stopForegroundCompat(R.string.foreground_service_started);
        }
    }
    
    /**
     * This is a wrapper around the new startForeground method, using the older
     * APIs if it is not available.
     */
    void startForegroundCompat(int id, Notification notification) {
        // If we have the new startForeground API, then use it.
        if (mStartForeground != null) {
            mStartForegroundArgs[0] = Integer.valueOf(id);
            mStartForegroundArgs[1] = notification;
            try {
                mStartForeground.invoke(this, mStartForegroundArgs);
            } catch (InvocationTargetException e) {
                // Should not happen.
                Log.w("ApiDemos", "Unable to invoke startForeground", e);
            } catch (IllegalAccessException e) {
                // Should not happen.
                Log.w("ApiDemos", "Unable to invoke startForeground", e);
            }
            return;
        }
        
        // Fall back on the old API.
        setForeground(true);
        mNM.notify(id, notification);
    }
    
    /**
     * This is a wrapper around the new stopForeground method, using the older
     * APIs if it is not available.
     */
    void stopForegroundCompat(int id) {
        // If we have the new stopForeground API, then use it.
        if (mStopForeground != null) {
            mStopForegroundArgs[0] = Boolean.TRUE;
            try {
                mStopForeground.invoke(this, mStopForegroundArgs);
            } catch (InvocationTargetException e) {
                // Should not happen.
                Log.w("ApiDemos", "Unable to invoke stopForeground", e);
            } catch (IllegalAccessException e) {
                // Should not happen.
                Log.w("ApiDemos", "Unable to invoke stopForeground", e);
            }
            return;
        }
        
        // Fall back on the old API.  Note to cancel BEFORE changing the
        // foreground state, since we could be killed at that point.
        mNM.cancel(id);
        setForeground(false);
    }
    
    @Override
    public void onDestroy() {
        // Make sure our notification is gone.
        stopForegroundCompat(R.string.foreground_service_started);
    }

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