Home | History | Annotate | Download | only in recommendation 
      1 /*
      2  * Copyright (C) 2016 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.printservice.recommendation;
     18 
     19 import android.annotation.Nullable;
     20 import android.annotation.SystemApi;
     21 import android.app.Service;
     22 import android.content.Context;
     23 import android.content.Intent;
     24 import android.os.Handler;
     25 import android.os.IBinder;
     26 import android.os.Looper;
     27 import android.os.Message;
     28 import android.os.RemoteException;
     29 import android.util.Log;
     30 
     31 import java.util.List;
     32 
     33 /**
     34  * Base class for the print service recommendation services.
     35  *
     36  * @hide
     37  */
     38 @SystemApi
     39 public abstract class RecommendationService extends Service {
     40     private static final String LOG_TAG = "PrintServiceRecS";
     41 
     42     /** Used to push onConnect and onDisconnect on the main thread */
     43     private Handler mHandler;
     44 
     45     /**
     46      * The {@link Intent} action that must be declared as handled by a service in its manifest for
     47      * the system to recognize it as a print service recommendation service.
     48      */
     49     public static final String SERVICE_INTERFACE =
     50             "android.printservice.recommendation.RecommendationService";
     51 
     52     /** Registered callbacks, only modified on main thread */
     53     private IRecommendationServiceCallbacks mCallbacks;
     54 
     55     @Override
     56     protected void attachBaseContext(Context base) {
     57         super.attachBaseContext(base);
     58 
     59         mHandler = new MyHandler();
     60     }
     61 
     62     /**
     63      * Update the print service recommendations.
     64      *
     65      * @param recommendations The new set of recommendations
     66      */
     67     public final void updateRecommendations(@Nullable List<RecommendationInfo> recommendations) {
     68         mHandler.obtainMessage(MyHandler.MSG_UPDATE, recommendations).sendToTarget();
     69     }
     70 
     71     @Override
     72     public final IBinder onBind(Intent intent) {
     73         return new IRecommendationService.Stub() {
     74             @Override
     75             public void registerCallbacks(IRecommendationServiceCallbacks callbacks) {
     76                 // The callbacks come in order of the caller on oneway calls. Hence while the caller
     77                 // cannot know at what time the connection is made, he can know the ordering of
     78                 // connection and disconnection.
     79                 //
     80                 // Similar he cannot know when the disconnection is processed, hence he has to
     81                 // handle callbacks after calling disconnect.
     82                 if (callbacks != null) {
     83                     mHandler.obtainMessage(MyHandler.MSG_CONNECT, callbacks).sendToTarget();
     84                 } else {
     85                     mHandler.obtainMessage(MyHandler.MSG_DISCONNECT).sendToTarget();
     86                 }
     87             }
     88         };
     89     }
     90 
     91     /**
     92      * Called when the client connects to the recommendation service.
     93      */
     94     public abstract void onConnected();
     95 
     96     /**
     97      * Called when the client disconnects from the recommendation service.
     98      */
     99     public abstract void onDisconnected();
    100 
    101     private class MyHandler extends Handler {
    102         static final int MSG_CONNECT = 1;
    103         static final int MSG_DISCONNECT = 2;
    104         static final int MSG_UPDATE = 3;
    105 
    106         MyHandler() {
    107             super(Looper.getMainLooper());
    108         }
    109 
    110         @Override
    111         public void handleMessage(Message msg) {
    112             switch (msg.what) {
    113                 case MSG_CONNECT:
    114                     mCallbacks = (IRecommendationServiceCallbacks) msg.obj;
    115                     onConnected();
    116                     break;
    117                 case MSG_DISCONNECT:
    118                     onDisconnected();
    119                     mCallbacks = null;
    120                     break;
    121                 case MSG_UPDATE:
    122                     // Note that there might be a connection change in progress. In this case the
    123                     // message is handled as before the change. This is acceptable as the caller of
    124                     // the connection change has not guarantee when the connection change binder
    125                     // transaction is actually processed.
    126                     try {
    127                         mCallbacks.onRecommendationsUpdated((List<RecommendationInfo>) msg.obj);
    128                     } catch (RemoteException | NullPointerException e) {
    129                         Log.e(LOG_TAG, "Could not update recommended services", e);
    130                     }
    131                     break;
    132             }
    133         }
    134     }
    135 }
    136