811a5a4a |
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 | |
17 | package android.support.v2.widget; |
18 | |
19 | import android.content.Context; |
20 | import android.database.ContentObserver; |
21 | import android.database.Cursor; |
22 | import android.database.DataSetObserver; |
23 | import android.os.Handler; |
24 | import android.util.Config; |
25 | import android.util.Log; |
26 | import android.view.View; |
27 | import android.view.ViewGroup; |
28 | import android.widget.BaseAdapter; |
29 | import android.widget.Filter; |
30 | import android.widget.FilterQueryProvider; |
31 | import android.widget.Filterable; |
32 | |
33 | /** |
34 | * Static library support version of the framework's {@link android.widget.CursorAdapter}. |
35 | * Used to write apps that run on platforms prior to Android 3.0. When running |
36 | * on Android 3.0 or above, this implementation is still used; it does not try |
37 | * to switch to the framework's implementation. See the framework SDK |
38 | * documentation for a class overview. |
39 | */ |
40 | public abstract class CursorAdapter extends BaseAdapter implements Filterable, |
41 | CursorFilter.CursorFilterClient { |
42 | /** |
43 | * This field should be made private, so it is hidden from the SDK. |
44 | * {@hide} |
45 | */ |
46 | protected boolean mDataValid; |
47 | /** |
48 | * This field should be made private, so it is hidden from the SDK. |
49 | * {@hide} |
50 | */ |
51 | protected boolean mAutoRequery; |
52 | /** |
53 | * This field should be made private, so it is hidden from the SDK. |
54 | * {@hide} |
55 | */ |
56 | protected Cursor mCursor; |
57 | /** |
58 | * This field should be made private, so it is hidden from the SDK. |
59 | * {@hide} |
60 | */ |
61 | protected Context mContext; |
62 | /** |
63 | * This field should be made private, so it is hidden from the SDK. |
64 | * {@hide} |
65 | */ |
66 | protected int mRowIDColumn; |
67 | /** |
68 | * This field should be made private, so it is hidden from the SDK. |
69 | * {@hide} |
70 | */ |
71 | protected ChangeObserver mChangeObserver; |
72 | /** |
73 | * This field should be made private, so it is hidden from the SDK. |
74 | * {@hide} |
75 | */ |
76 | protected DataSetObserver mDataSetObserver; |
77 | /** |
78 | * This field should be made private, so it is hidden from the SDK. |
79 | * {@hide} |
80 | */ |
81 | protected CursorFilter mCursorFilter; |
82 | /** |
83 | * This field should be made private, so it is hidden from the SDK. |
84 | * {@hide} |
85 | */ |
86 | protected FilterQueryProvider mFilterQueryProvider; |
87 | |
88 | /** |
89 | * If set the adapter will call requery() on the cursor whenever a content change |
90 | * notification is delivered. Implies {@link #FLAG_REGISTER_CONTENT_OBSERVER}. |
91 | * |
92 | * @deprecated This option is discouraged, as it results in Cursor queries |
93 | * being performed on the application's UI thread and thus can cause poor |
94 | * responsiveness or even Application Not Responding errors. As an alternative, |
95 | * use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}. |
96 | */ |
97 | @Deprecated |
98 | public static final int FLAG_AUTO_REQUERY = 0x01; |
99 | |
100 | /** |
101 | * If set the adapter will register a content observer on the cursor and will call |
102 | * {@link #onContentChanged()} when a notification comes in. Be careful when |
103 | * using this flag: you will need to unset the current Cursor from the adapter |
104 | * to avoid leaks due to its registered observers. This flag is not needed |
105 | * when using a CursorAdapter with a |
106 | * {@link android.content.CursorLoader}. |
107 | */ |
108 | public static final int FLAG_REGISTER_CONTENT_OBSERVER = 0x02; |
109 | |
110 | /** |
111 | * Constructor that always enables auto-requery. |
112 | * |
113 | * @deprecated This option is discouraged, as it results in Cursor queries |
114 | * being performed on the application's UI thread and thus can cause poor |
115 | * responsiveness or even Application Not Responding errors. As an alternative, |
116 | * use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}. |
117 | * |
118 | * @param c The cursor from which to get the data. |
119 | * @param context The context |
120 | */ |
121 | @Deprecated |
122 | public CursorAdapter(Context context, Cursor c) { |
123 | init(context, c, FLAG_AUTO_REQUERY); |
124 | } |
125 | |
126 | /** |
127 | * Constructor that allows control over auto-requery. It is recommended |
128 | * you not use this, but instead {@link #CursorAdapter(Context, Cursor, int)}. |
129 | * When using this constructor, {@link #FLAG_REGISTER_CONTENT_OBSERVER} |
130 | * will always be set. |
131 | * |
132 | * @param c The cursor from which to get the data. |
133 | * @param context The context |
134 | * @param autoRequery If true the adapter will call requery() on the |
135 | * cursor whenever it changes so the most recent |
136 | * data is always displayed. Using true here is discouraged. |
137 | */ |
138 | public CursorAdapter(Context context, Cursor c, boolean autoRequery) { |
139 | init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER); |
140 | } |
141 | |
142 | /** |
143 | * Recommended constructor. |
144 | * |
145 | * @param c The cursor from which to get the data. |
146 | * @param context The context |
147 | * @param flags Flags used to determine the behavior of the adapter; may |
148 | * be any combination of {@link #FLAG_AUTO_REQUERY} and |
149 | * {@link #FLAG_REGISTER_CONTENT_OBSERVER}. |
150 | */ |
151 | public CursorAdapter(Context context, Cursor c, int flags) { |
152 | init(context, c, flags); |
153 | } |
154 | |
155 | /** |
156 | * @deprecated Don't use this, use the normal constructor. This will |
157 | * be removed in the future. |
158 | */ |
159 | @Deprecated |
160 | protected void init(Context context, Cursor c, boolean autoRequery) { |
161 | init(context, c, autoRequery ? FLAG_AUTO_REQUERY : FLAG_REGISTER_CONTENT_OBSERVER); |
162 | } |
163 | |
164 | void init(Context context, Cursor c, int flags) { |
165 | if ((flags & FLAG_AUTO_REQUERY) == FLAG_AUTO_REQUERY) { |
166 | flags |= FLAG_REGISTER_CONTENT_OBSERVER; |
167 | mAutoRequery = true; |
168 | } else { |
169 | mAutoRequery = false; |
170 | } |
171 | boolean cursorPresent = c != null; |
172 | mCursor = c; |
173 | mDataValid = cursorPresent; |
174 | mContext = context; |
175 | mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; |
176 | if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) { |
177 | mChangeObserver = new ChangeObserver(); |
178 | mDataSetObserver = new MyDataSetObserver(); |
179 | } else { |
180 | mChangeObserver = null; |
181 | mDataSetObserver = null; |
182 | } |
183 | |
184 | if (cursorPresent) { |
185 | if (mChangeObserver != null) c.registerContentObserver(mChangeObserver); |
186 | if (mDataSetObserver != null) c.registerDataSetObserver(mDataSetObserver); |
187 | } |
188 | } |
189 | |
190 | /** |
191 | * Returns the cursor. |
192 | * @return the cursor. |
193 | */ |
194 | public Cursor getCursor() { |
195 | return mCursor; |
196 | } |
197 | |
198 | /** |
199 | * @see android.widget.ListAdapter#getCount() |
200 | */ |
201 | public int getCount() { |
202 | if (mDataValid && mCursor != null) { |
203 | return mCursor.getCount(); |
204 | } else { |
205 | return 0; |
206 | } |
207 | } |
208 | |
209 | /** |
210 | * @see android.widget.ListAdapter#getItem(int) |
211 | */ |
212 | public Object getItem(int position) { |
213 | if (mDataValid && mCursor != null) { |
214 | mCursor.moveToPosition(position); |
215 | return mCursor; |
216 | } else { |
217 | return null; |
218 | } |
219 | } |
220 | |
221 | /** |
222 | * @see android.widget.ListAdapter#getItemId(int) |
223 | */ |
224 | public long getItemId(int position) { |
225 | if (mDataValid && mCursor != null) { |
226 | if (mCursor.moveToPosition(position)) { |
227 | return mCursor.getLong(mRowIDColumn); |
228 | } else { |
229 | return 0; |
230 | } |
231 | } else { |
232 | return 0; |
233 | } |
234 | } |
235 | |
236 | @Override |
237 | public boolean hasStableIds() { |
238 | return true; |
239 | } |
240 | |
241 | /** |
242 | * @see android.widget.ListAdapter#getView(int, View, ViewGroup) |
243 | */ |
244 | public View getView(int position, View convertView, ViewGroup parent) { |
245 | if (!mDataValid) { |
246 | throw new IllegalStateException("this should only be called when the cursor is valid"); |
247 | } |
248 | if (!mCursor.moveToPosition(position)) { |
249 | throw new IllegalStateException("couldn't move cursor to position " + position); |
250 | } |
251 | View v; |
252 | if (convertView == null) { |
253 | v = newView(mContext, mCursor, parent); |
254 | } else { |
255 | v = convertView; |
256 | } |
257 | bindView(v, mContext, mCursor); |
258 | return v; |
259 | } |
260 | |
261 | @Override |
262 | public View getDropDownView(int position, View convertView, ViewGroup parent) { |
263 | if (mDataValid) { |
264 | mCursor.moveToPosition(position); |
265 | View v; |
266 | if (convertView == null) { |
267 | v = newDropDownView(mContext, mCursor, parent); |
268 | } else { |
269 | v = convertView; |
270 | } |
271 | bindView(v, mContext, mCursor); |
272 | return v; |
273 | } else { |
274 | return null; |
275 | } |
276 | } |
277 | |
278 | /** |
279 | * Makes a new view to hold the data pointed to by cursor. |
280 | * @param context Interface to application's global information |
281 | * @param cursor The cursor from which to get the data. The cursor is already |
282 | * moved to the correct position. |
283 | * @param parent The parent to which the new view is attached to |
284 | * @return the newly created view. |
285 | */ |
286 | public abstract View newView(Context context, Cursor cursor, ViewGroup parent); |
287 | |
288 | /** |
289 | * Makes a new drop down view to hold the data pointed to by cursor. |
290 | * @param context Interface to application's global information |
291 | * @param cursor The cursor from which to get the data. The cursor is already |
292 | * moved to the correct position. |
293 | * @param parent The parent to which the new view is attached to |
294 | * @return the newly created view. |
295 | */ |
296 | public View newDropDownView(Context context, Cursor cursor, ViewGroup parent) { |
297 | return newView(context, cursor, parent); |
298 | } |
299 | |
300 | /** |
301 | * Bind an existing view to the data pointed to by cursor |
302 | * @param view Existing view, returned earlier by newView |
303 | * @param context Interface to application's global information |
304 | * @param cursor The cursor from which to get the data. The cursor is already |
305 | * moved to the correct position. |
306 | */ |
307 | public abstract void bindView(View view, Context context, Cursor cursor); |
308 | |
309 | /** |
310 | * Change the underlying cursor to a new cursor. If there is an existing cursor it will be |
311 | * closed. |
312 | * |
313 | * @param cursor The new cursor to be used |
314 | */ |
315 | public void changeCursor(Cursor cursor) { |
316 | Cursor old = swapCursor(cursor); |
317 | if (old != null) { |
318 | old.close(); |
319 | } |
320 | } |
321 | |
322 | /** |
323 | * Swap in a new Cursor, returning the old Cursor. Unlike |
324 | * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em> |
325 | * closed. |
326 | * |
327 | * @param newCursor The new cursor to be used. |
328 | * @return Returns the previously set Cursor, or null if there wasa not one. |
329 | * If the given new Cursor is the same instance is the previously set |
330 | * Cursor, null is also returned. |
331 | */ |
332 | public Cursor swapCursor(Cursor newCursor) { |
333 | if (newCursor == mCursor) { |
334 | return null; |
335 | } |
336 | Cursor oldCursor = mCursor; |
337 | if (oldCursor != null) { |
338 | if (mChangeObserver != null) oldCursor.unregisterContentObserver(mChangeObserver); |
339 | if (mDataSetObserver != null) oldCursor.unregisterDataSetObserver(mDataSetObserver); |
340 | } |
341 | mCursor = newCursor; |
342 | if (newCursor != null) { |
343 | if (mChangeObserver != null) newCursor.registerContentObserver(mChangeObserver); |
344 | if (mDataSetObserver != null) newCursor.registerDataSetObserver(mDataSetObserver); |
345 | mRowIDColumn = newCursor.getColumnIndexOrThrow("_id"); |
346 | mDataValid = true; |
347 | // notify the observers about the new cursor |
348 | notifyDataSetChanged(); |
349 | } else { |
350 | mRowIDColumn = -1; |
351 | mDataValid = false; |
352 | // notify the observers about the lack of a data set |
353 | notifyDataSetInvalidated(); |
354 | } |
355 | return oldCursor; |
356 | } |
357 | |
358 | /** |
359 | * <p>Converts the cursor into a CharSequence. Subclasses should override this |
360 | * method to convert their results. The default implementation returns an |
361 | * empty String for null values or the default String representation of |
362 | * the value.</p> |
363 | * |
364 | * @param cursor the cursor to convert to a CharSequence |
365 | * @return a CharSequence representing the value |
366 | */ |
367 | public CharSequence convertToString(Cursor cursor) { |
368 | return cursor == null ? "" : cursor.toString(); |
369 | } |
370 | |
371 | /** |
372 | * Runs a query with the specified constraint. This query is requested |
373 | * by the filter attached to this adapter. |
374 | * |
375 | * The query is provided by a |
376 | * {@link android.widget.FilterQueryProvider}. |
377 | * If no provider is specified, the current cursor is not filtered and returned. |
378 | * |
379 | * After this method returns the resulting cursor is passed to {@link #changeCursor(Cursor)} |
380 | * and the previous cursor is closed. |
381 | * |
382 | * This method is always executed on a background thread, not on the |
383 | * application's main thread (or UI thread.) |
384 | * |
385 | * Contract: when constraint is null or empty, the original results, |
386 | * prior to any filtering, must be returned. |
387 | * |
388 | * @param constraint the constraint with which the query must be filtered |
389 | * |
390 | * @return a Cursor representing the results of the new query |
391 | * |
392 | * @see #getFilter() |
393 | * @see #getFilterQueryProvider() |
394 | * @see #setFilterQueryProvider(android.widget.FilterQueryProvider) |
395 | */ |
396 | public Cursor runQueryOnBackgroundThread(CharSequence constraint) { |
397 | if (mFilterQueryProvider != null) { |
398 | return mFilterQueryProvider.runQuery(constraint); |
399 | } |
400 | |
401 | return mCursor; |
402 | } |
403 | |
404 | public Filter getFilter() { |
405 | if (mCursorFilter == null) { |
406 | mCursorFilter = new CursorFilter(this); |
407 | } |
408 | return mCursorFilter; |
409 | } |
410 | |
411 | /** |
412 | * Returns the query filter provider used for filtering. When the |
413 | * provider is null, no filtering occurs. |
414 | * |
415 | * @return the current filter query provider or null if it does not exist |
416 | * |
417 | * @see #setFilterQueryProvider(android.widget.FilterQueryProvider) |
418 | * @see #runQueryOnBackgroundThread(CharSequence) |
419 | */ |
420 | public FilterQueryProvider getFilterQueryProvider() { |
421 | return mFilterQueryProvider; |
422 | } |
423 | |
424 | /** |
425 | * Sets the query filter provider used to filter the current Cursor. |
426 | * The provider's |
427 | * {@link android.widget.FilterQueryProvider#runQuery(CharSequence)} |
428 | * method is invoked when filtering is requested by a client of |
429 | * this adapter. |
430 | * |
431 | * @param filterQueryProvider the filter query provider or null to remove it |
432 | * |
433 | * @see #getFilterQueryProvider() |
434 | * @see #runQueryOnBackgroundThread(CharSequence) |
435 | */ |
436 | public void setFilterQueryProvider(FilterQueryProvider filterQueryProvider) { |
437 | mFilterQueryProvider = filterQueryProvider; |
438 | } |
439 | |
440 | /** |
441 | * Called when the {@link ContentObserver} on the cursor receives a change notification. |
442 | * The default implementation provides the auto-requery logic, but may be overridden by |
443 | * sub classes. |
444 | * |
445 | * @see ContentObserver#onChange(boolean) |
446 | */ |
447 | protected void onContentChanged() { |
448 | if (mAutoRequery && mCursor != null && !mCursor.isClosed()) { |
449 | if (Config.LOGV) Log.v("Cursor", "Auto requerying " + mCursor + " due to update"); |
450 | mDataValid = mCursor.requery(); |
451 | } |
452 | } |
453 | |
454 | private class ChangeObserver extends ContentObserver { |
455 | public ChangeObserver() { |
456 | super(new Handler()); |
457 | } |
458 | |
459 | @Override |
460 | public boolean deliverSelfNotifications() { |
461 | return true; |
462 | } |
463 | |
464 | @Override |
465 | public void onChange(boolean selfChange) { |
466 | onContentChanged(); |
467 | } |
468 | } |
469 | |
470 | private class MyDataSetObserver extends DataSetObserver { |
471 | @Override |
472 | public void onChanged() { |
473 | mDataValid = true; |
474 | notifyDataSetChanged(); |
475 | } |
476 | |
477 | @Override |
478 | public void onInvalidated() { |
479 | mDataValid = false; |
480 | notifyDataSetInvalidated(); |
481 | } |
482 | } |
483 | |
484 | } |