Android Api Demos登頂之路（三十二）Alarm Service

這個demo示範了如何利用鬧鐘定時器啟動一個服務，用法與上一個demo基本類似，隻是啟動的是服務而上個demo 發送是的廣播。

* 這裡需要注意的是：在本例中每隔20秒啟動一次服務，而服務在啟動後，向系統通知欄中發送了一個通知消息 而後單獨開啟一個線程去執行服務中需要進行的複雜操作，操作完成後結束服務。

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="@string/info" />
    <Button 
        android:id="@+id/start_service_schedule"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Alarm Service"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="5dp"/>
    <Button 
        android:id="@+id/stop_service_schedule"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Stop Alarm Service"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="5dp"/>

</LinearLayout>
           

MainActivity.java

public class MainActivity extends Activity {
    private PendingIntent senderService;
    private AlarmManager am;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Intent intent = new Intent(MainActivity.this, AlarmService.class);
        senderService = PendingIntent.getService(MainActivity.this, , intent,
                );

        setContentView(R.layout.activity_main);
        am = (AlarmManager) getSystemService(ALARM_SERVICE);

        Button bt_start = (Button) findViewById(R.id.start_service_schedule);
        Button bt_stop = (Button) findViewById(R.id.stop_service_schedule);
        bt_start.setOnClickListener(startServiceListener);
        bt_stop.setOnClickListener(stopServiceListener);
    }

    private OnClickListener startServiceListener = new OnClickListener() {
        @Override
        public void onClick(View v) {
            long firstTime = SystemClock.elapsedRealtime();
            am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, firstTime,
                     * , senderService);
            Toast.makeText(MainActivity.this, "定時啟動服務任務已經開啟！", ).show();
        }
    };

    private OnClickListener stopServiceListener = new OnClickListener() {
        @Override
        public void onClick(View v) {
            am.cancel(senderService);
            Toast.makeText(MainActivity.this, "定時啟動服務任務已經停止！", ).show();
        }
    };

}
           

AlarmService.java

public class AlarmService extends Service {
    private static final int NOTIFICATION_ID = ;
    private NotificationManager nm;

    @Override
    public void onCreate() {
        super.onCreate();
        // 擷取系統通知管理器
        nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        // 向系統通知欄發送通知消息,并在通知欄中顯示消息
        showNotification();
        // AlarmService表示為線程的名稱
        Thread thr = new Thread(null, mTask, "AlarmService");
        thr.start();
    }

    private Runnable mTask=new Runnable() {
        @Override
        public void run() {
            long endTime=System.currentTimeMillis()+*;
            while(System.currentTimeMillis()<endTime){
                //加一把同步鎖
                synchronized (mBinder) {
                    try {
                        mBinder.wait(endTime-System.currentTimeMillis());
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
            //結束服務
            AlarmService.this.stopSelf();
        }
    };
    //定義一個IBinder接口的執行個體
    private IBinder mBinder=new Binder(){
        @Override
        protected boolean onTransact(int code, Parcel data, Parcel reply,
                int flags) throws RemoteException {
            // TODO Auto-generated method stub
            return super.onTransact(code, data, reply, flags);
        }
    };

    @SuppressWarnings("deprecation")
    private void showNotification() {
        String text = "服務正在運作...";
        String label = "鬧鐘定時服務示例！";
        // 定義一個延遲意圖，當我們點選這條通知消息時，再次啟動我們的主程式
        PendingIntent contentIntent = PendingIntent.getActivity(this, ,
                new Intent(this, MainActivity.class), );
        // 定義一個notification
        Notification.Builder builder = new Builder(this);
        builder.setSmallIcon(R.drawable.stat_sample);
        builder.setContentText(text);
        builder.setWhen(System.currentTimeMillis());
        builder.setContentTitle(label);
        builder.setContentIntent(contentIntent);
        builder.setTicker(text);
        Notification notification = builder.build();
        //Notification notification=new Notification(R.drawable.stat_sample, text, System.currentTimeMillis());

        // 設定在系統通知欄中顯示的通知消息的界面資訊
         //notification.setLatestEventInfo(this, label, text, contentIntent);
        //發送消息通知
        nm.notify(NOTIFICATION_ID, notification);
    }

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

    @Override
    public void onDestroy() {
        super.onDestroy();
        //根據notification的Id取消對應的系統通知
        nm.cancel(NOTIFICATION_ID);
        Toast.makeText(this, "服務結束！", ).show();
    }

}
           

最後别忘了在配置檔案中對服務進行配置