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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.printservice.recommendation;
import android.annotation.Nullable;
import android.annotation.SystemApi;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.RemoteException;
import android.util.Log;
import java.util.List;
/**
* Base class for the print service recommendation services.
*
* @hide
*/
@SystemApi
public abstract class RecommendationService extends Service {
private static final String LOG_TAG = "PrintServiceRecS";
/** Used to push onConnect and onDisconnect on the main thread */
private Handler mHandler;
/**
* The {@link Intent} action that must be declared as handled by a service in its manifest for
* the system to recognize it as a print service recommendation service.
*/
public static final String SERVICE_INTERFACE =
"android.printservice.recommendation.RecommendationService";
/** Registered callbacks, only modified on main thread */
private IRecommendationServiceCallbacks mCallbacks;
@Override
protected void attachBaseContext(Context base) {
super.attachBaseContext(base);
mHandler = new MyHandler();
}
/**
* Update the print service recommendations.
*
* @param recommendations The new set of recommendations
*/
public final void updateRecommendations(@Nullable List<RecommendationInfo> recommendations) {
mHandler.obtainMessage(MyHandler.MSG_UPDATE, recommendations).sendToTarget();
}
@Override
public final IBinder onBind(Intent intent) {
return new IRecommendationService.Stub() {
@Override
public void registerCallbacks(IRecommendationServiceCallbacks callbacks) {
// The callbacks come in order of the caller on oneway calls. Hence while the caller
// cannot know at what time the connection is made, he can know the ordering of
// connection and disconnection.
//
// Similar he cannot know when the disconnection is processed, hence he has to
// handle callbacks after calling disconnect.
if (callbacks != null) {
mHandler.obtainMessage(MyHandler.MSG_CONNECT, callbacks).sendToTarget();
} else {
mHandler.obtainMessage(MyHandler.MSG_DISCONNECT).sendToTarget();
}
}
};
}
/**
* Called when the client connects to the recommendation service.
*/
public abstract void onConnected();
/**
* Called when the client disconnects from the recommendation service.
*/
public abstract void onDisconnected();
private class MyHandler extends Handler {
static final int MSG_CONNECT = 1;
static final int MSG_DISCONNECT = 2;
static final int MSG_UPDATE = 3;
MyHandler() {
super(Looper.getMainLooper());
}
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_CONNECT:
mCallbacks = (IRecommendationServiceCallbacks) msg.obj;
onConnected();
break;
case MSG_DISCONNECT:
onDisconnected();
mCallbacks = null;
break;
case MSG_UPDATE:
if (mCallbacks != null) {
// Note that there might be a connection change in progress. In this case
// the message is handled as before the change. This is acceptable as the
// caller of the connection change has not guarantee when the connection
// change binder transaction is actually processed.
try {
mCallbacks.onRecommendationsUpdated((List<RecommendationInfo>) msg.obj);
} catch (RemoteException | NullPointerException e) {
Log.e(LOG_TAG, "Could not update recommended services", e);
}
}
break;
}
}
}
}
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