ResultReceiver.java revision d3c5347b3ec0025ec906e2053eaa9b97287c46a5 
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
17package android.support.v4.os;
18
19import android.os.Bundle;
20import android.os.Handler;
21import android.os.Parcel;
22import android.os.Parcelable;
23import android.os.RemoteException;
24import android.support.v4.os.IResultReceiver;
25
26/**
27 * Generic interface for receiving a callback result from someone.  Use this
28 * by creating a subclass and implement {@link #onReceiveResult}, which you can
29 * then pass to others and send through IPC, and receive results they
30 * supply with {@link #send}.
31 *
32 * <p>Note: the implementation underneath is just a simple wrapper around
33 * a {@link Binder} that is used to perform the communication.  This means
34 * semantically you should treat it as such: this class does not impact process
35 * lifecycle management (you must be using some higher-level component to tell
36 * the system that your process needs to continue running), the connection will
37 * break if your process goes away for any reason, etc.</p>
38 * @hide
39 */
40public class ResultReceiver implements Parcelable {
41    final boolean mLocal;
42    final Handler mHandler;
43
44    IResultReceiver mReceiver;
45
46    class MyRunnable implements Runnable {
47        final int mResultCode;
48        final Bundle mResultData;
49
50        MyRunnable(int resultCode, Bundle resultData) {
51            mResultCode = resultCode;
52            mResultData = resultData;
53        }
54
55        public void run() {
56            onReceiveResult(mResultCode, mResultData);
57        }
58    }
59
60    class MyResultReceiver extends IResultReceiver.Stub {
61        public void send(int resultCode, Bundle resultData) {
62            if (mHandler != null) {
63                mHandler.post(new MyRunnable(resultCode, resultData));
64            } else {
65                onReceiveResult(resultCode, resultData);
66            }
67        }
68    }
69
70    /**
71     * Create a new ResultReceive to receive results.  Your
72     * {@link #onReceiveResult} method will be called from the thread running
73     * <var>handler</var> if given, or from an arbitrary thread if null.
74     */
75    public ResultReceiver(Handler handler) {
76        mLocal = true;
77        mHandler = handler;
78    }
79
80    /**
81     * Deliver a result to this receiver.  Will call {@link #onReceiveResult},
82     * always asynchronously if the receiver has supplied a Handler in which
83     * to dispatch the result.
84     * @param resultCode Arbitrary result code to deliver, as defined by you.
85     * @param resultData Any additional data provided by you.
86     */
87    public void send(int resultCode, Bundle resultData) {
88        if (mLocal) {
89            if (mHandler != null) {
90                mHandler.post(new MyRunnable(resultCode, resultData));
91            } else {
92                onReceiveResult(resultCode, resultData);
93            }
94            return;
95        }
96
97        if (mReceiver != null) {
98            try {
99                mReceiver.send(resultCode, resultData);
100            } catch (RemoteException e) {
101            }
102        }
103    }
104
105    /**
106     * Override to receive results delivered to this object.
107     *
108     * @param resultCode Arbitrary result code delivered by the sender, as
109     * defined by the sender.
110     * @param resultData Any additional data provided by the sender.
111     */
112    protected void onReceiveResult(int resultCode, Bundle resultData) {
113    }
114
115    public int describeContents() {
116        return 0;
117    }
118
119    public void writeToParcel(Parcel out, int flags) {
120        synchronized (this) {
121            if (mReceiver == null) {
122                mReceiver = new MyResultReceiver();
123            }
124            out.writeStrongBinder(mReceiver.asBinder());
125        }
126    }
127
128    ResultReceiver(Parcel in) {
129        mLocal = false;
130        mHandler = null;
131        mReceiver = IResultReceiver.Stub.asInterface(in.readStrongBinder());
132    }
133
134    public static final Creator<ResultReceiver> CREATOR
135            = new Creator<ResultReceiver>() {
136        public ResultReceiver createFromParcel(Parcel in) {
137            return new ResultReceiver(in);
138        }
139        public ResultReceiver[] newArray(int size) {
140            return new ResultReceiver[size];
141        }
142    };
143}
144