1/*
2 * Copyright (C) 2011 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.content;
18
19import java.util.ArrayList;
20import java.util.HashMap;
21import java.util.Set;
22
23import android.content.BroadcastReceiver;
24import android.content.Context;
25import android.content.Intent;
26import android.content.IntentFilter;
27import android.net.Uri;
28import android.os.Handler;
29import android.os.Message;
30import android.util.Log;
31
32/**
33 * Helper to register for and send broadcasts of Intents to local objects
34 * within your process.  This has a number of advantages over sending
35 * global broadcasts with {@link android.content.Context#sendBroadcast}:
36 * <ul>
37 * <li> You know that the data you are broadcasting won't leave your app, so
38 * don't need to worry about leaking private data.
39 * <li> It is not possible for other applications to send these broadcasts to
40 * your app, so you don't need to worry about having security holes they can
41 * exploit.
42 * <li> It is more efficient than sending a global broadcast through the
43 * system.
44 * </ul>
45 */
46public final class LocalBroadcastManager {
47    private static class ReceiverRecord {
48        final IntentFilter filter;
49        final BroadcastReceiver receiver;
50        boolean broadcasting;
51
52        ReceiverRecord(IntentFilter _filter, BroadcastReceiver _receiver) {
53            filter = _filter;
54            receiver = _receiver;
55        }
56
57        @Override
58        public String toString() {
59            StringBuilder builder = new StringBuilder(128);
60            builder.append("Receiver{");
61            builder.append(receiver);
62            builder.append(" filter=");
63            builder.append(filter);
64            builder.append("}");
65            return builder.toString();
66        }
67    }
68
69    private static class BroadcastRecord {
70        final Intent intent;
71        final ArrayList<ReceiverRecord> receivers;
72
73        BroadcastRecord(Intent _intent, ArrayList<ReceiverRecord> _receivers) {
74            intent = _intent;
75            receivers = _receivers;
76        }
77    }
78
79    private static final String TAG = "LocalBroadcastManager";
80    private static final boolean DEBUG = false;
81
82    private final Context mAppContext;
83
84    private final HashMap<BroadcastReceiver, ArrayList<IntentFilter>> mReceivers
85            = new HashMap<BroadcastReceiver, ArrayList<IntentFilter>>();
86    private final HashMap<String, ArrayList<ReceiverRecord>> mActions
87            = new HashMap<String, ArrayList<ReceiverRecord>>();
88
89    private final ArrayList<BroadcastRecord> mPendingBroadcasts
90            = new ArrayList<BroadcastRecord>();
91
92    static final int MSG_EXEC_PENDING_BROADCASTS = 1;
93
94    private final Handler mHandler;
95
96    private static final Object mLock = new Object();
97    private static LocalBroadcastManager mInstance;
98
99    public static LocalBroadcastManager getInstance(Context context) {
100        synchronized (mLock) {
101            if (mInstance == null) {
102                mInstance = new LocalBroadcastManager(context.getApplicationContext());
103            }
104            return mInstance;
105        }
106    }
107
108    private LocalBroadcastManager(Context context) {
109        mAppContext = context;
110        mHandler = new Handler(context.getMainLooper()) {
111
112            @Override
113            public void handleMessage(Message msg) {
114                switch (msg.what) {
115                    case MSG_EXEC_PENDING_BROADCASTS:
116                        executePendingBroadcasts();
117                        break;
118                    default:
119                        super.handleMessage(msg);
120                }
121            }
122        };
123    }
124
125    /**
126     * Register a receive for any local broadcasts that match the given IntentFilter.
127     *
128     * @param receiver The BroadcastReceiver to handle the broadcast.
129     * @param filter Selects the Intent broadcasts to be received.
130     *
131     * @see #unregisterReceiver
132     */
133    public void registerReceiver(BroadcastReceiver receiver, IntentFilter filter) {
134        synchronized (mReceivers) {
135            ReceiverRecord entry = new ReceiverRecord(filter, receiver);
136            ArrayList<IntentFilter> filters = mReceivers.get(receiver);
137            if (filters == null) {
138                filters = new ArrayList<IntentFilter>(1);
139                mReceivers.put(receiver, filters);
140            }
141            filters.add(filter);
142            for (int i=0; i<filter.countActions(); i++) {
143                String action = filter.getAction(i);
144                ArrayList<ReceiverRecord> entries = mActions.get(action);
145                if (entries == null) {
146                    entries = new ArrayList<ReceiverRecord>(1);
147                    mActions.put(action, entries);
148                }
149                entries.add(entry);
150            }
151        }
152    }
153
154    /**
155     * Unregister a previously registered BroadcastReceiver.  <em>All</em>
156     * filters that have been registered for this BroadcastReceiver will be
157     * removed.
158     *
159     * @param receiver The BroadcastReceiver to unregister.
160     *
161     * @see #registerReceiver
162     */
163    public void unregisterReceiver(BroadcastReceiver receiver) {
164        synchronized (mReceivers) {
165            ArrayList<IntentFilter> filters = mReceivers.remove(receiver);
166            if (filters == null) {
167                return;
168            }
169            for (int i=0; i<filters.size(); i++) {
170                IntentFilter filter = filters.get(i);
171                for (int j=0; j<filter.countActions(); j++) {
172                    String action = filter.getAction(j);
173                    ArrayList<ReceiverRecord> receivers = mActions.get(action);
174                    if (receivers != null) {
175                        for (int k=0; k<receivers.size(); k++) {
176                            if (receivers.get(k).receiver == receiver) {
177                                receivers.remove(k);
178                                k--;
179                            }
180                        }
181                        if (receivers.size() <= 0) {
182                            mActions.remove(action);
183                        }
184                    }
185                }
186            }
187        }
188    }
189
190    /**
191     * Broadcast the given intent to all interested BroadcastReceivers.  This
192     * call is asynchronous; it returns immediately, and you will continue
193     * executing while the receivers are run.
194     *
195     * @param intent The Intent to broadcast; all receivers matching this
196     *     Intent will receive the broadcast.
197     *
198     * @see #registerReceiver
199     */
200    public boolean sendBroadcast(Intent intent) {
201        synchronized (mReceivers) {
202            final String action = intent.getAction();
203            final String type = intent.resolveTypeIfNeeded(
204                    mAppContext.getContentResolver());
205            final Uri data = intent.getData();
206            final String scheme = intent.getScheme();
207            final Set<String> categories = intent.getCategories();
208
209            final boolean debug = DEBUG ||
210                    ((intent.getFlags() & Intent.FLAG_DEBUG_LOG_RESOLUTION) != 0);
211            if (debug) Log.v(
212                    TAG, "Resolving type " + type + " scheme " + scheme
213                    + " of intent " + intent);
214
215            ArrayList<ReceiverRecord> entries = mActions.get(intent.getAction());
216            if (entries != null) {
217                if (debug) Log.v(TAG, "Action list: " + entries);
218
219                ArrayList<ReceiverRecord> receivers = null;
220                for (int i=0; i<entries.size(); i++) {
221                    ReceiverRecord receiver = entries.get(i);
222                    if (debug) Log.v(TAG, "Matching against filter " + receiver.filter);
223
224                    if (receiver.broadcasting) {
225                        if (debug) {
226                            Log.v(TAG, "  Filter's target already added");
227                        }
228                        continue;
229                    }
230
231                    int match = receiver.filter.match(action, type, scheme, data,
232                            categories, "LocalBroadcastManager");
233                    if (match >= 0) {
234                        if (debug) Log.v(TAG, "  Filter matched!  match=0x" +
235                                Integer.toHexString(match));
236                        if (receivers == null) {
237                            receivers = new ArrayList<ReceiverRecord>();
238                        }
239                        receivers.add(receiver);
240                        receiver.broadcasting = true;
241                    } else {
242                        if (debug) {
243                            String reason;
244                            switch (match) {
245                                case IntentFilter.NO_MATCH_ACTION: reason = "action"; break;
246                                case IntentFilter.NO_MATCH_CATEGORY: reason = "category"; break;
247                                case IntentFilter.NO_MATCH_DATA: reason = "data"; break;
248                                case IntentFilter.NO_MATCH_TYPE: reason = "type"; break;
249                                default: reason = "unknown reason"; break;
250                            }
251                            Log.v(TAG, "  Filter did not match: " + reason);
252                        }
253                    }
254                }
255
256                if (receivers != null) {
257                    for (int i=0; i<receivers.size(); i++) {
258                        receivers.get(i).broadcasting = false;
259                    }
260                    mPendingBroadcasts.add(new BroadcastRecord(intent, receivers));
261                    if (!mHandler.hasMessages(MSG_EXEC_PENDING_BROADCASTS)) {
262                        mHandler.sendEmptyMessage(MSG_EXEC_PENDING_BROADCASTS);
263                    }
264                    return true;
265                }
266            }
267        }
268        return false;
269    }
270
271    /**
272     * Like {@link #sendBroadcast(Intent)}, but if there are any receivers for
273     * the Intent this function will block and immediately dispatch them before
274     * returning.
275     */
276    public void sendBroadcastSync(Intent intent) {
277        if (sendBroadcast(intent)) {
278            executePendingBroadcasts();
279        }
280    }
281
282    private void executePendingBroadcasts() {
283        while (true) {
284            BroadcastRecord[] brs = null;
285            synchronized (mReceivers) {
286                final int N = mPendingBroadcasts.size();
287                if (N <= 0) {
288                    return;
289                }
290                brs = new BroadcastRecord[N];
291                mPendingBroadcasts.toArray(brs);
292                mPendingBroadcasts.clear();
293            }
294            for (int i=0; i<brs.length; i++) {
295                BroadcastRecord br = brs[i];
296                for (int j=0; j<br.receivers.size(); j++) {
297                    br.receivers.get(j).receiver.onReceive(mAppContext, br.intent);
298                }
299            }
300        }
301    }
302}
303