Android example source code file (ForegroundService.java)

This example Android source code file (ForegroundService.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

activity, android, apidemos, app, application, class, illegalaccessexception, intent, invocationtargetexception, method, notification, notificationmanager, object, onclicklistener, os, override, reflection, string, ui, unable

The ForegroundService.java Android example source code

/*
 * 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.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

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];
    
    /**
     * 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 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;
        }
    }

    @Override
    public void onDestroy() {
        // Make sure our notification is gone.
        stopForegroundCompat(R.string.foreground_service_started);
    }



    // 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, Controller.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);
        }
    }
    
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
    
    // ----------------------------------------------------------------------

    /**
     * <p>Example of explicitly starting and stopping the {@link ForegroundService}.
     * 
     * <p>Note that this is implemented as an inner class only keep the sample
     * all together; typically this code would appear in some separate class.
     */
    public static class Controller extends Activity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            setContentView(R.layout.foreground_service_controller);

            // Watch for button clicks.
            Button button = (Button)findViewById(R.id.start_foreground);
            button.setOnClickListener(mForegroundListener);
            button = (Button)findViewById(R.id.start_background);
            button.setOnClickListener(mBackgroundListener);
            button = (Button)findViewById(R.id.stop);
            button.setOnClickListener(mStopListener);
        }

        private OnClickListener mForegroundListener = new OnClickListener() {
            public void onClick(View v) {
                Intent intent = new Intent(ForegroundService.ACTION_FOREGROUND);
                intent.setClass(Controller.this, ForegroundService.class);
                startService(intent);
            }
        };

        private OnClickListener mBackgroundListener = new OnClickListener() {
            public void onClick(View v) {
                Intent intent = new Intent(ForegroundService.ACTION_BACKGROUND);
                intent.setClass(Controller.this, ForegroundService.class);
                startService(intent);
            }
        };

        private OnClickListener mStopListener = new OnClickListener() {
            public void onClick(View v) {
                stopService(new Intent(Controller.this,
                        ForegroundService.class));
            }
        };
    }
}