（一） Extending the Binder class

通過 Binder 接口的形式實現(xiàn)，當(dāng) Activity 綁定 Service 成功的時候 Activity 會在<code> ServiceConnection </code>類的 <code>onServiceConnected()</code>回調(diào)方法中獲取到 Service 的 onBind()方法 return 過來的 Binder 的子類。

MyService

MainAcitivity

（二）Using a Messenger

MessengerService.java

public class MessengerService extends Service {

    private Messenger messenger = new Messenger(new IncomingHandler());
    private Messenger mActivityMessenger;


    @Override
    public IBinder onBind(Intent intent) {
        IBinder binder = messenger.getBinder();
        return binder;
    }

    class IncomingHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case 0:
                    Log.d("tag", msg.toString());
                    if (mActivityMessenger != null) {
                        Message message = new Message();
                        message.what = 2;
                        message.obj = "地瓜地瓜我是土豆";
                        try {
                            mActivityMessenger.send(message);
                        } catch (RemoteException e) {
                            e.printStackTrace();
                        }
                    }
                    break;

                case 1:
                    mActivityMessenger = (Messenger) msg.obj;
                    Log.d("tag", "已經(jīng)獲取到 Activity 發(fā)送了的 Messenger 對象");
                    break;

                default:
                    break;

            }
        }
    }
}

MessageActivity.java

public class MessageActivity extends AppCompatActivity {

    private Messenger messenger;
    private Messenger mOutMessenger = new Messenger(new OutgoingHandler());

    private ServiceConnection conn = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            Toast.makeText(MessageActivity.this, "連接成功！", Toast.LENGTH_SHORT).show();
            messenger = new Messenger(service);
            Message message = new Message();
            message.what = 1;
            message.obj = mOutMessenger;
            try {
                messenger.send(message);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            Toast.makeText(MessageActivity.this, "連接已經(jīng)斷開！", Toast.LENGTH_SHORT).show();
        }
    };


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_message);
    }

    /**
     * 綁定服務(wù)
     *
     * @param view
     */
    public void click1(View view) {
        Intent intent = new Intent(this, MessengerService.class);
        bindService(intent, conn, BIND_AUTO_CREATE);
    }

    /**
     * 發(fā)送消息
     *
     * @param view
     */
    public void click2(View view) {
        if (messenger == null) {
            Toast.makeText(this, "服務(wù)不可用！", Toast.LENGTH_SHORT).show();
            return;
        }
        Message message = new Message();
        message.obj = "長江長江我是黃河";
        message.what = 0;
        try {
            messenger.send(message);
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }

    class OutgoingHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            Log.d("tag", msg.toString());
        }
    }
}

（三）Using AIDL

AIDL 比較適合當(dāng)客戶端和服務(wù)端不在同一個應(yīng)用下的場景。
有點多啊哈哈哈，可以看這篇IPC機制——AIDL的簡單梳理