notification对象，如：
Notification notification = new Notification(R.drawable.icon, getText(R.string.ticker_text), System.currentTimeMillis()); Intent notificationIntent = new Intent(this, ExampleActivity.class); PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0); notification.setLatestEventInfo(this, getText(R.string.notification_title), getText(R.string.notification_message), pendingIntent); startForeground(ONGOING_NOTIFICATION_ID, notification); 注：ID值不能为0； 要从前台移除服务，请调用 stopForeground()。此方法接收一个布尔值，指示是否也移除状态栏通知。 此方法不会停止 服务。 但是，如果在服务正在前台运行时将其停止，则通知也会被移除。 3.定义可绑定的服务： a.定义和客户（client）交互的接口有三种方式，分别是： （1）继承Binder类，适用于此服务为应用进程所私有，且client跟该服务处于同一应用进程中； 实现步骤：服务中定义一个类继承Binder类，在服务的onBind（）方法中返回一个自定义Binder实例对象，client在 onServiceConnected（）方法中获取该对象； （2）使用Messager类提供跨进程绑定服务： 实现步骤： 服务实现一个 Handler，由其接收来自client的每个调用的回调， Handler 用于创建 Messenger 对象（对 Handler 的引用）， Messenger 创建一个 IBinder，服务通过 onBind() 使其返回client， client使用 IBinder 将 Messenger（引用服务的 Handler）实例化，然后使用后者将 Message 对象发送给服务， 服务在其 Handler 中（具体地讲，是在 handleMessage() 方法中）接收每个 Message。 这样，client并没有调用服务的“方法”。而client传递的“消息”（Message 对象）是服务在其 Handler 中接收的。 如：service： public class MessengerService extends Service { /** Command to the service to display a message */ static final int MSG_SAY_HELLO = 1; /** * Handler of incoming messages from clients. */ class IncomingHandler extends Handler { @Override public void handleMessage(Message msg) { switch (msg.what) { case MSG_SAY_HELLO: Toast.makeText(getApplicationContext(), "hello!", Toast.LENGTH_SHORT).show(); break; default: super.handleMessage(msg); } } } /** * Target we publish for clients to send messages to IncomingHandler. */ final Messenger mMessenger = new Messenger(new IncomingHandler()); /** * When binding to the service, we return an interface to our messenger * for sending messages to the service. */ @Override public IBinder onBind(Intent intent) { Toast.makeText(getApplicationContext(), "binding", Toast.LENGTH_SHORT).show(); return mMessenger.getBinder(); } } Activity： public class ActivityMessenger extends Activity { /** Messenger for communicating with the service. */ Messenger mService = null; /** Flag indicating whether we have called bind on the service. */ boolean mBound; /** * Class for interacting with the main interface of the service. */ private ServiceConnection mConnection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { // This is called when the connection with the service has been // established, giving us the object we can use to // interact with the service. We are communicating with the // service using a Messenger, so here we get a client-side // representation of that from the raw IBinder object. mService = new Messenger(service); mBound = true; } public void onServiceDisconnected(ComponentName className) { // This is called when the connection with the service has been // unexpectedly disconnected -- that is, its process crashed. mService = null; mBound = false; } }; public void sayHello(View v) { if (!mBound) return; // Create and send a message to the service, using a supported 'what' value Message msg = Message.obtain(null, MessengerService.MSG_SAY_HELLO, 0, 0); try { mService.send(msg); } catch (RemoteException e) { e.printStackTrace(); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } @Override protected void onStart() { super.onStart(); // Bind to the service bindService(new Intent(this, MessengerService.class), mConnection, Context.BIND_AUTO_CREATE); } @Override protected void onStop() { super.onStop(); // Unbind from the service if (mBound) { unbindService(mConnection); mBound = false; } } }（3）AIDL，有待后续拓展
4.客户端（client）绑定服务： client调用bindService(）方法，然后服务会调用onBind（）方法返回IBinder对象，但是因为 这个绑定过程是异步的，bindService()调用后立即结束并不会返回IBinder()对象，因此需要一个ServiceConnection实例， 这个借口提供onServiceConnected（）和onServiceDisconnected（）回调方法，当服务已经绑定时会调用onServiceConnected()方法， 并获得IBinder实例对象；当服务崩溃或者被系统杀死时onServiceDisconnected（）方法调用，而不是用户调用unbindService()时调用。 如：
LocalService mService; private ServiceConnection mConnection = new ServiceConnection() { // Called when the connection with the service is established public void onServiceConnected(ComponentName className, IBinder service) { // Because we have bound to an explicit // service that is running in our own process, we can // cast its IBinder to a concrete class and directly access it. LocalBinder binder = (LocalBinder) service; mService = binder.getService(); mBound = true; } // Called when the connection with the service disconnects unexpectedly public void onServiceDisconnected(ComponentName className) { Log.e(TAG, "onServiceDisconnected"); mBound = false; } };绑定服务：
Intent intent = new Intent(this, LocalService.class); bindService(intent, mConnection, Context.BIND_AUTO_CREATE); 5.bind service 生命周期：
6.Service完整生命周期：
