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      1 /*
      2  * Copyright (C) 2009 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.os;
     18 
     19 import com.android.internal.os.IResultReceiver;
     20 
     21 /**
     22  * Generic interface for receiving a callback result from someone.  Use this
     23  * by creating a subclass and implement {@link #onReceiveResult}, which you can
     24  * then pass to others and send through IPC, and receive results they
     25  * supply with {@link #send}.
     26  *
     27  * <p>Note: the implementation underneath is just a simple wrapper around
     28  * a {@link Binder} that is used to perform the communication.  This means
     29  * semantically you should treat it as such: this class does not impact process
     30  * lifecycle management (you must be using some higher-level component to tell
     31  * the system that your process needs to continue running), the connection will
     32  * break if your process goes away for any reason, etc.</p>
     33  */
     34 public class ResultReceiver implements Parcelable {
     35     final boolean mLocal;
     36     final Handler mHandler;
     37 
     38     IResultReceiver mReceiver;
     39 
     40     class MyRunnable implements Runnable {
     41         final int mResultCode;
     42         final Bundle mResultData;
     43 
     44         MyRunnable(int resultCode, Bundle resultData) {
     45             mResultCode = resultCode;
     46             mResultData = resultData;
     47         }
     48 
     49         public void run() {
     50             onReceiveResult(mResultCode, mResultData);
     51         }
     52     }
     53 
     54     class MyResultReceiver extends IResultReceiver.Stub {
     55         public void send(int resultCode, Bundle resultData) {
     56             if (mHandler != null) {
     57                 mHandler.post(new MyRunnable(resultCode, resultData));
     58             } else {
     59                 onReceiveResult(resultCode, resultData);
     60             }
     61         }
     62     }
     63 
     64     /**
     65      * Create a new ResultReceive to receive results.  Your
     66      * {@link #onReceiveResult} method will be called from the thread running
     67      * <var>handler</var> if given, or from an arbitrary thread if null.
     68      */
     69     public ResultReceiver(Handler handler) {
     70         mLocal = true;
     71         mHandler = handler;
     72     }
     73 
     74     /**
     75      * Deliver a result to this receiver.  Will call {@link #onReceiveResult},
     76      * always asynchronously if the receiver has supplied a Handler in which
     77      * to dispatch the result.
     78      * @param resultCode Arbitrary result code to deliver, as defined by you.
     79      * @param resultData Any additional data provided by you.
     80      */
     81     public void send(int resultCode, Bundle resultData) {
     82         if (mLocal) {
     83             if (mHandler != null) {
     84                 mHandler.post(new MyRunnable(resultCode, resultData));
     85             } else {
     86                 onReceiveResult(resultCode, resultData);
     87             }
     88             return;
     89         }
     90 
     91         if (mReceiver != null) {
     92             try {
     93                 mReceiver.send(resultCode, resultData);
     94             } catch (RemoteException e) {
     95             }
     96         }
     97     }
     98 
     99     /**
    100      * Override to receive results delivered to this object.
    101      *
    102      * @param resultCode Arbitrary result code delivered by the sender, as
    103      * defined by the sender.
    104      * @param resultData Any additional data provided by the sender.
    105      */
    106     protected void onReceiveResult(int resultCode, Bundle resultData) {
    107     }
    108 
    109     public int describeContents() {
    110         return 0;
    111     }
    112 
    113     public void writeToParcel(Parcel out, int flags) {
    114         synchronized (this) {
    115             if (mReceiver == null) {
    116                 mReceiver = new MyResultReceiver();
    117             }
    118             out.writeStrongBinder(mReceiver.asBinder());
    119         }
    120     }
    121 
    122     ResultReceiver(Parcel in) {
    123         mLocal = false;
    124         mHandler = null;
    125         mReceiver = IResultReceiver.Stub.asInterface(in.readStrongBinder());
    126     }
    127 
    128     public static final Parcelable.Creator<ResultReceiver> CREATOR
    129             = new Parcelable.Creator<ResultReceiver>() {
    130         public ResultReceiver createFromParcel(Parcel in) {
    131             return new ResultReceiver(in);
    132         }
    133         public ResultReceiver[] newArray(int size) {
    134             return new ResultReceiver[size];
    135         }
    136     };
    137 }
    138