我們有時會遇到這樣的情況，當(dāng)手機(jī)處于睡眠狀態(tài)時，到了某個時間點，我們需要做一些必要的事情。這是如何做到的呢？我們首先會想到鬧鐘，設(shè)置一個鬧鐘，到了設(shè)置的時間點，鬧鐘就會響。當(dāng)然，還有很多其他的應(yīng)用...
下面給出一個例子，方便學(xué)習(xí)和查閱

BroadcastReceiver

package com.android.test;

import android.app.Service;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.os.PowerManager;

import android.util.Log;

public class TestUpdateReceiver extends BroadcastReceiver{

private static final String TAG = "TestUpdateReceiver";

private static final boolean DEBUG = true;

static final Object mStartingServiceSync = new Object();

static PowerManager.WakeLock mStartingService;

private Context mContext = null;

@SuppressWarnings("deprecation")

@Override

public void onReceive(Context context, Intent intent) {

if(mContext == null) mContext = context;

if(DEBUG){

Log.v(TAG, "====================action=" + intent.getAction());

}

Intent i = new Intent();

i.setClass(mContext, TestUpdateService.class);

i.putExtras(intent);

i.putExtra("action", intent.getAction());

beginStartingService(mContext, i);

}

public static void beginStartingService(Context context, Intent intent) {

synchronized (mStartingServiceSync) {

if (mStartingService == null) {

PowerManager pm =

(PowerManager)context.getSystemService(Context.POWER_SERVICE);

mStartingService = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK,

"StartingAlertService");

mStartingService.setReferenceCounted(false);

}

mStartingService.acquire();

context.startService(intent);

}

}

/**

* Called back by the service when it has finished processing notifications,

* releasing the wake lock if the service is now stopping.

*/

public static void finishStartingService(Service service, int startId) {

synchronized (mStartingServiceSync) {

if (mStartingService != null) {

if (service.stopSelfResult(startId)) {

mStartingService.release();

}

}

}

}

}

同時啟動一個服務(wù)

package com.android.test;

public class TestUpdateService extends Service{

private static final String TAG = "TestUpdateService";

private static final boolean DEBUG = true;

@Override

public IBinder onBind(Intent intent) {

// TODO Auto-generated method stub

return null;

}

private volatile Looper mServiceLooper = null;

private volatile Handler mUpdateHandler;

private class UpdateHandler extends Handler{

public UpdateHandler(Looper looper) {

super(looper);

}

@Override

public void handleMessage(Message msg) {

// TODO Auto-generated method stub

processMessage(msg);

TestUpdateReceiver.finishStartingService(TestUpdateService.this, msg.arg1);

}

}

@Override

public void onCreate() {

// TODO Auto-generated method stub

super.onCreate();

mContext = this;

HandlerThread thread = new HandlerThread("TestUpdateService");

thread.start();

mServiceLooper = thread.getLooper();

mUpdateHandler = new UpdateHandler(mServiceLooper);

}

@Override

public int onStartCommand(Intent intent, int flags, int startId) {

// TODO Auto-generated method stub

if(intent != null){

Message msg = mUpdateHandler.obtainMessage();

msg.obj = intent.getExtras();

msg.arg1 = startId;

mUpdateHandler.sendMessage(msg);

}

return START_REDELIVER_INTENT;

}

private void processMessage(Message msg){

Bundle bundle = (Bundle) msg.obj;

String action = bundle.getString("action");

if(DEBUG){

Log.v(TAG, "processMessage(Message msg)=================action=" + action);

}

/*在這里做你要做的事情*/

/*在這里做你要做的事情*/

/*在這里做你要做的事情*/

}

}

原理是先設(shè)一個鬧鐘，等待鬧鐘發(fā)送廣播，TestUpdateReceiver接收該廣播，并獲得 PowerManager.WakeLock的一個實例mStartingService ，并執(zhí)行 mStartingService.acquire()，然后去做你想做的事情，最后執(zhí)行mStartingService . release ( ) 把獲得的lock釋放掉。關(guān)于電源管理的知識，請查閱其他資料。

最后，不要忘了在配置文件里加相應(yīng)的權(quán)限

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