The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2006 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.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 | |
| 29 | /** |
| 30 | * Adapter that exposes data from a {@link android.database.Cursor Cursor} to a |
| 31 | * {@link android.widget.ListView ListView} widget. The Cursor must include |
| 32 | * a column named "_id" or this class will not work. |
| 33 | */ |
| 34 | public abstract class CursorAdapter extends BaseAdapter implements Filterable, |
| 35 | CursorFilter.CursorFilterClient { |
| 36 | /** |
| 37 | * This field should be made private, so it is hidden from the SDK. |
| 38 | * {@hide} |
| 39 | */ |
| 40 | protected boolean mDataValid; |
| 41 | /** |
| 42 | * This field should be made private, so it is hidden from the SDK. |
| 43 | * {@hide} |
| 44 | */ |
| 45 | protected boolean mAutoRequery; |
| 46 | /** |
| 47 | * This field should be made private, so it is hidden from the SDK. |
| 48 | * {@hide} |
| 49 | */ |
| 50 | protected Cursor mCursor; |
| 51 | /** |
| 52 | * This field should be made private, so it is hidden from the SDK. |
| 53 | * {@hide} |
| 54 | */ |
| 55 | protected Context mContext; |
| 56 | /** |
| 57 | * This field should be made private, so it is hidden from the SDK. |
| 58 | * {@hide} |
| 59 | */ |
| 60 | protected int mRowIDColumn; |
| 61 | /** |
| 62 | * This field should be made private, so it is hidden from the SDK. |
| 63 | * {@hide} |
| 64 | */ |
| 65 | protected ChangeObserver mChangeObserver; |
| 66 | /** |
| 67 | * This field should be made private, so it is hidden from the SDK. |
| 68 | * {@hide} |
| 69 | */ |
| 70 | protected DataSetObserver mDataSetObserver = new MyDataSetObserver(); |
| 71 | /** |
| 72 | * This field should be made private, so it is hidden from the SDK. |
| 73 | * {@hide} |
| 74 | */ |
| 75 | protected CursorFilter mCursorFilter; |
| 76 | /** |
| 77 | * This field should be made private, so it is hidden from the SDK. |
| 78 | * {@hide} |
| 79 | */ |
| 80 | protected FilterQueryProvider mFilterQueryProvider; |
| 81 | |
| 82 | /** |
| 83 | * Constructor. The adapter will call requery() on the cursor whenever |
| 84 | * it changes so that the most recent data is always displayed. |
| 85 | * |
| 86 | * @param c The cursor from which to get the data. |
| 87 | * @param context The context |
| 88 | */ |
| 89 | public CursorAdapter(Context context, Cursor c) { |
| 90 | init(context, c, true); |
| 91 | } |
| 92 | |
| 93 | /** |
| 94 | * Constructor |
| 95 | * @param c The cursor from which to get the data. |
| 96 | * @param context The context |
| 97 | * @param autoRequery If true the adapter will call requery() on the |
| 98 | * cursor whenever it changes so the most recent |
| 99 | * data is always displayed. |
| 100 | */ |
| 101 | public CursorAdapter(Context context, Cursor c, boolean autoRequery) { |
| 102 | init(context, c, autoRequery); |
| 103 | } |
| 104 | |
| 105 | protected void init(Context context, Cursor c, boolean autoRequery) { |
| 106 | boolean cursorPresent = c != null; |
| 107 | mAutoRequery = autoRequery; |
| 108 | mCursor = c; |
| 109 | mDataValid = cursorPresent; |
| 110 | mContext = context; |
| 111 | mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; |
| 112 | mChangeObserver = new ChangeObserver(); |
| 113 | if (cursorPresent) { |
| 114 | c.registerContentObserver(mChangeObserver); |
| 115 | c.registerDataSetObserver(mDataSetObserver); |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | /** |
| 120 | * Returns the cursor. |
| 121 | * @return the cursor. |
| 122 | */ |
| 123 | public Cursor getCursor() { |
| 124 | return mCursor; |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * @see android.widget.ListAdapter#getCount() |
| 129 | */ |
Jeff Hamilton | 2c6b3b0 | 2009-03-24 19:32:26 -0700 | [diff] [blame^] | 130 | public int getCount() { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 131 | if (mDataValid && mCursor != null) { |
| 132 | return mCursor.getCount(); |
| 133 | } else { |
| 134 | return 0; |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * @see android.widget.ListAdapter#getItem(int) |
| 140 | */ |
Jeff Hamilton | 2c6b3b0 | 2009-03-24 19:32:26 -0700 | [diff] [blame^] | 141 | public Object getItem(int position) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 142 | if (mDataValid && mCursor != null) { |
| 143 | mCursor.moveToPosition(position); |
| 144 | return mCursor; |
| 145 | } else { |
| 146 | return null; |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * @see android.widget.ListAdapter#getItemId(int) |
| 152 | */ |
Jeff Hamilton | 2c6b3b0 | 2009-03-24 19:32:26 -0700 | [diff] [blame^] | 153 | public long getItemId(int position) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 154 | if (mDataValid && mCursor != null) { |
| 155 | if (mCursor.moveToPosition(position)) { |
| 156 | return mCursor.getLong(mRowIDColumn); |
| 157 | } else { |
| 158 | return 0; |
| 159 | } |
| 160 | } else { |
| 161 | return 0; |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | @Override |
| 166 | public boolean hasStableIds() { |
| 167 | return true; |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * @see android.widget.ListAdapter#getView(int, View, ViewGroup) |
| 172 | */ |
| 173 | public View getView(int position, View convertView, ViewGroup parent) { |
| 174 | if (!mDataValid) { |
| 175 | throw new IllegalStateException("this should only be called when the cursor is valid"); |
| 176 | } |
| 177 | if (!mCursor.moveToPosition(position)) { |
| 178 | throw new IllegalStateException("couldn't move cursor to position " + position); |
| 179 | } |
| 180 | View v; |
| 181 | if (convertView == null) { |
| 182 | v = newView(mContext, mCursor, parent); |
| 183 | } else { |
| 184 | v = convertView; |
| 185 | } |
| 186 | bindView(v, mContext, mCursor); |
| 187 | return v; |
| 188 | } |
| 189 | |
| 190 | @Override |
| 191 | public View getDropDownView(int position, View convertView, ViewGroup parent) { |
| 192 | if (mDataValid) { |
| 193 | mCursor.moveToPosition(position); |
| 194 | View v; |
| 195 | if (convertView == null) { |
| 196 | v = newDropDownView(mContext, mCursor, parent); |
| 197 | } else { |
| 198 | v = convertView; |
| 199 | } |
| 200 | bindView(v, mContext, mCursor); |
| 201 | return v; |
| 202 | } else { |
| 203 | return null; |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Makes a new view to hold the data pointed to by cursor. |
| 209 | * @param context Interface to application's global information |
| 210 | * @param cursor The cursor from which to get the data. The cursor is already |
| 211 | * moved to the correct position. |
| 212 | * @param parent The parent to which the new view is attached to |
| 213 | * @return the newly created view. |
| 214 | */ |
| 215 | public abstract View newView(Context context, Cursor cursor, ViewGroup parent); |
| 216 | |
| 217 | /** |
| 218 | * Makes a new drop down view to hold the data pointed to by cursor. |
| 219 | * @param context Interface to application's global information |
| 220 | * @param cursor The cursor from which to get the data. The cursor is already |
| 221 | * moved to the correct position. |
| 222 | * @param parent The parent to which the new view is attached to |
| 223 | * @return the newly created view. |
| 224 | */ |
| 225 | public View newDropDownView(Context context, Cursor cursor, ViewGroup parent) { |
| 226 | return newView(context, cursor, parent); |
| 227 | } |
| 228 | |
| 229 | /** |
| 230 | * Bind an existing view to the data pointed to by cursor |
| 231 | * @param view Existing view, returned earlier by newView |
| 232 | * @param context Interface to application's global information |
| 233 | * @param cursor The cursor from which to get the data. The cursor is already |
| 234 | * moved to the correct position. |
| 235 | */ |
| 236 | public abstract void bindView(View view, Context context, Cursor cursor); |
| 237 | |
| 238 | /** |
| 239 | * Change the underlying cursor to a new cursor. If there is an existing cursor it will be |
| 240 | * closed. |
| 241 | * |
| 242 | * @param cursor the new cursor to be used |
| 243 | */ |
| 244 | public void changeCursor(Cursor cursor) { |
| 245 | if (cursor == mCursor) { |
| 246 | return; |
| 247 | } |
| 248 | if (mCursor != null) { |
| 249 | mCursor.unregisterContentObserver(mChangeObserver); |
| 250 | mCursor.unregisterDataSetObserver(mDataSetObserver); |
| 251 | mCursor.close(); |
| 252 | } |
| 253 | mCursor = cursor; |
| 254 | if (cursor != null) { |
| 255 | cursor.registerContentObserver(mChangeObserver); |
| 256 | cursor.registerDataSetObserver(mDataSetObserver); |
| 257 | mRowIDColumn = cursor.getColumnIndexOrThrow("_id"); |
| 258 | mDataValid = true; |
| 259 | // notify the observers about the new cursor |
| 260 | notifyDataSetChanged(); |
| 261 | } else { |
| 262 | mRowIDColumn = -1; |
| 263 | mDataValid = false; |
| 264 | // notify the observers about the lack of a data set |
| 265 | notifyDataSetInvalidated(); |
| 266 | } |
| 267 | } |
| 268 | |
| 269 | /** |
| 270 | * <p>Converts the cursor into a CharSequence. Subclasses should override this |
| 271 | * method to convert their results. The default implementation returns an |
| 272 | * empty String for null values or the default String representation of |
| 273 | * the value.</p> |
| 274 | * |
| 275 | * @param cursor the cursor to convert to a CharSequence |
| 276 | * @return a CharSequence representing the value |
| 277 | */ |
| 278 | public CharSequence convertToString(Cursor cursor) { |
| 279 | return cursor == null ? "" : cursor.toString(); |
| 280 | } |
| 281 | |
| 282 | /** |
| 283 | * Runs a query with the specified constraint. This query is requested |
| 284 | * by the filter attached to this adapter. |
| 285 | * |
| 286 | * The query is provided by a |
| 287 | * {@link android.widget.FilterQueryProvider}. |
| 288 | * If no provider is specified, the current cursor is not filtered and returned. |
| 289 | * |
| 290 | * After this method returns the resulting cursor is passed to {@link #changeCursor(Cursor)} |
| 291 | * and the previous cursor is closed. |
| 292 | * |
| 293 | * This method is always executed on a background thread, not on the |
| 294 | * application's main thread (or UI thread.) |
| 295 | * |
| 296 | * Contract: when constraint is null or empty, the original results, |
| 297 | * prior to any filtering, must be returned. |
| 298 | * |
| 299 | * @param constraint the constraint with which the query must be filtered |
| 300 | * |
| 301 | * @return a Cursor representing the results of the new query |
| 302 | * |
| 303 | * @see #getFilter() |
| 304 | * @see #getFilterQueryProvider() |
| 305 | * @see #setFilterQueryProvider(android.widget.FilterQueryProvider) |
| 306 | */ |
| 307 | public Cursor runQueryOnBackgroundThread(CharSequence constraint) { |
| 308 | if (mFilterQueryProvider != null) { |
| 309 | return mFilterQueryProvider.runQuery(constraint); |
| 310 | } |
| 311 | |
| 312 | return mCursor; |
| 313 | } |
| 314 | |
| 315 | public Filter getFilter() { |
| 316 | if (mCursorFilter == null) { |
| 317 | mCursorFilter = new CursorFilter(this); |
| 318 | } |
| 319 | return mCursorFilter; |
| 320 | } |
| 321 | |
| 322 | /** |
| 323 | * Returns the query filter provider used for filtering. When the |
| 324 | * provider is null, no filtering occurs. |
| 325 | * |
| 326 | * @return the current filter query provider or null if it does not exist |
| 327 | * |
| 328 | * @see #setFilterQueryProvider(android.widget.FilterQueryProvider) |
| 329 | * @see #runQueryOnBackgroundThread(CharSequence) |
| 330 | */ |
| 331 | public FilterQueryProvider getFilterQueryProvider() { |
| 332 | return mFilterQueryProvider; |
| 333 | } |
| 334 | |
| 335 | /** |
| 336 | * Sets the query filter provider used to filter the current Cursor. |
| 337 | * The provider's |
| 338 | * {@link android.widget.FilterQueryProvider#runQuery(CharSequence)} |
| 339 | * method is invoked when filtering is requested by a client of |
| 340 | * this adapter. |
| 341 | * |
| 342 | * @param filterQueryProvider the filter query provider or null to remove it |
| 343 | * |
| 344 | * @see #getFilterQueryProvider() |
| 345 | * @see #runQueryOnBackgroundThread(CharSequence) |
| 346 | */ |
| 347 | public void setFilterQueryProvider(FilterQueryProvider filterQueryProvider) { |
| 348 | mFilterQueryProvider = filterQueryProvider; |
| 349 | } |
| 350 | |
| 351 | /** |
| 352 | * Called when the {@link ContentObserver} on the cursor receives a change notification. |
| 353 | * The default implementation provides the auto-requery logic, but may be overridden by |
| 354 | * sub classes. |
| 355 | * |
| 356 | * @see ContentObserver#onChange(boolean) |
| 357 | * @hide pending API Council approval |
| 358 | */ |
| 359 | protected void onContentChanged() { |
| 360 | if (mAutoRequery && mCursor != null && !mCursor.isClosed()) { |
| 361 | if (Config.LOGV) Log.v("Cursor", "Auto requerying " + mCursor + " due to update"); |
| 362 | mDataValid = mCursor.requery(); |
| 363 | } |
| 364 | } |
| 365 | |
| 366 | private class ChangeObserver extends ContentObserver { |
| 367 | public ChangeObserver() { |
| 368 | super(new Handler()); |
| 369 | } |
| 370 | |
| 371 | @Override |
| 372 | public boolean deliverSelfNotifications() { |
| 373 | return true; |
| 374 | } |
| 375 | |
| 376 | @Override |
| 377 | public void onChange(boolean selfChange) { |
| 378 | onContentChanged(); |
| 379 | } |
| 380 | } |
| 381 | |
| 382 | private class MyDataSetObserver extends DataSetObserver { |
| 383 | @Override |
| 384 | public void onChanged() { |
| 385 | mDataValid = true; |
| 386 | notifyDataSetChanged(); |
| 387 | } |
| 388 | |
| 389 | @Override |
| 390 | public void onInvalidated() { |
| 391 | mDataValid = false; |
| 392 | notifyDataSetInvalidated(); |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | } |