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      1 /*
      2  * Copyright (C) 2015 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.support.v4.os;
     18 
     19 import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP;
     20 
     21 import android.os.Bundle;
     22 import android.os.Handler;
     23 import android.os.Parcel;
     24 import android.os.Parcelable;
     25 import android.os.RemoteException;
     26 import android.support.annotation.RestrictTo;
     27 
     28 /**
     29  * Generic interface for receiving a callback result from someone.  Use this
     30  * by creating a subclass and implement {@link #onReceiveResult}, which you can
     31  * then pass to others and send through IPC, and receive results they
     32  * supply with {@link #send}.
     33  *
     34  * <p>Note: the implementation underneath is just a simple wrapper around
     35  * a {@link Binder} that is used to perform the communication.  This means
     36  * semantically you should treat it as such: this class does not impact process
     37  * lifecycle management (you must be using some higher-level component to tell
     38  * the system that your process needs to continue running), the connection will
     39  * break if your process goes away for any reason, etc.</p>
     40  * @hide
     41  */
     42 @RestrictTo(LIBRARY_GROUP)
     43 public class ResultReceiver implements Parcelable {
     44     final boolean mLocal;
     45     final Handler mHandler;
     46 
     47     IResultReceiver mReceiver;
     48 
     49     class MyRunnable implements Runnable {
     50         final int mResultCode;
     51         final Bundle mResultData;
     52 
     53         MyRunnable(int resultCode, Bundle resultData) {
     54             mResultCode = resultCode;
     55             mResultData = resultData;
     56         }
     57 
     58         @Override
     59         public void run() {
     60             onReceiveResult(mResultCode, mResultData);
     61         }
     62     }
     63 
     64     class MyResultReceiver extends IResultReceiver.Stub {
     65         @Override
     66         public void send(int resultCode, Bundle resultData) {
     67             if (mHandler != null) {
     68                 mHandler.post(new MyRunnable(resultCode, resultData));
     69             } else {
     70                 onReceiveResult(resultCode, resultData);
     71             }
     72         }
     73     }
     74 
     75     /**
     76      * Create a new ResultReceive to receive results.  Your
     77      * {@link #onReceiveResult} method will be called from the thread running
     78      * <var>handler</var> if given, or from an arbitrary thread if null.
     79      */
     80     public ResultReceiver(Handler handler) {
     81         mLocal = true;
     82         mHandler = handler;
     83     }
     84 
     85     /**
     86      * Deliver a result to this receiver.  Will call {@link #onReceiveResult},
     87      * always asynchronously if the receiver has supplied a Handler in which
     88      * to dispatch the result.
     89      * @param resultCode Arbitrary result code to deliver, as defined by you.
     90      * @param resultData Any additional data provided by you.
     91      */
     92     public void send(int resultCode, Bundle resultData) {
     93         if (mLocal) {
     94             if (mHandler != null) {
     95                 mHandler.post(new MyRunnable(resultCode, resultData));
     96             } else {
     97                 onReceiveResult(resultCode, resultData);
     98             }
     99             return;
    100         }
    101 
    102         if (mReceiver != null) {
    103             try {
    104                 mReceiver.send(resultCode, resultData);
    105             } catch (RemoteException e) {
    106             }
    107         }
    108     }
    109 
    110     /**
    111      * Override to receive results delivered to this object.
    112      *
    113      * @param resultCode Arbitrary result code delivered by the sender, as
    114      * defined by the sender.
    115      * @param resultData Any additional data provided by the sender.
    116      */
    117     protected void onReceiveResult(int resultCode, Bundle resultData) {
    118     }
    119 
    120     @Override
    121     public int describeContents() {
    122         return 0;
    123     }
    124 
    125     @Override
    126     public void writeToParcel(Parcel out, int flags) {
    127         synchronized (this) {
    128             if (mReceiver == null) {
    129                 mReceiver = new MyResultReceiver();
    130             }
    131             out.writeStrongBinder(mReceiver.asBinder());
    132         }
    133     }
    134 
    135     ResultReceiver(Parcel in) {
    136         mLocal = false;
    137         mHandler = null;
    138         mReceiver = IResultReceiver.Stub.asInterface(in.readStrongBinder());
    139     }
    140 
    141     public static final Creator<ResultReceiver> CREATOR
    142             = new Creator<ResultReceiver>() {
    143         @Override
    144         public ResultReceiver createFromParcel(Parcel in) {
    145             return new ResultReceiver(in);
    146         }
    147         @Override
    148         public ResultReceiver[] newArray(int size) {
    149             return new ResultReceiver[size];
    150         }
    151     };
    152 }
    153