| /* |
| * Copyright (C) 2007 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package android.content; |
| |
| import android.database.Cursor; |
| import android.net.Uri; |
| import android.os.Handler; |
| import android.os.HandlerThread; |
| import android.os.Looper; |
| import android.os.Message; |
| import android.util.Log; |
| |
| import java.lang.ref.WeakReference; |
| |
| /** |
| * A helper class to help make handling asynchronous {@link ContentResolver} |
| * queries easier. |
| */ |
| public abstract class AsyncQueryHandler extends Handler { |
| private static final String TAG = "AsyncQuery"; |
| private static final boolean localLOGV = false; |
| |
| private static final int EVENT_ARG_QUERY = 1; |
| private static final int EVENT_ARG_INSERT = 2; |
| private static final int EVENT_ARG_UPDATE = 3; |
| private static final int EVENT_ARG_DELETE = 4; |
| private static final int EVENT_ARG_QUERY_ENTITIES = 5; |
| |
| /* package */ final WeakReference<ContentResolver> mResolver; |
| |
| private static Looper sLooper = null; |
| |
| private Handler mWorkerThreadHandler; |
| |
| protected static final class WorkerArgs { |
| public Uri uri; |
| public Handler handler; |
| public String[] projection; |
| public String selection; |
| public String[] selectionArgs; |
| public String orderBy; |
| public Object result; |
| public Object cookie; |
| public ContentValues values; |
| } |
| |
| protected class WorkerHandler extends Handler { |
| public WorkerHandler(Looper looper) { |
| super(looper); |
| } |
| |
| @Override |
| public void handleMessage(Message msg) { |
| final ContentResolver resolver = mResolver.get(); |
| if (resolver == null) return; |
| |
| WorkerArgs args = (WorkerArgs) msg.obj; |
| |
| int token = msg.what; |
| int event = msg.arg1; |
| |
| switch (event) { |
| case EVENT_ARG_QUERY: |
| Cursor cursor; |
| try { |
| cursor = resolver.query(args.uri, args.projection, |
| args.selection, args.selectionArgs, |
| args.orderBy); |
| // Calling getCount() causes the cursor window to be filled, |
| // which will make the first access on the main thread a lot faster. |
| if (cursor != null) { |
| cursor.getCount(); |
| } |
| } catch (Exception e) { |
| Log.w(TAG, e.toString()); |
| cursor = null; |
| } |
| |
| args.result = cursor; |
| break; |
| |
| case EVENT_ARG_QUERY_ENTITIES: |
| EntityIterator iterator = null; |
| try { |
| iterator = resolver.queryEntities(args.uri, args.selection, |
| args.selectionArgs, args.orderBy); |
| } catch (Exception e) { |
| Log.w(TAG, e.toString()); |
| } |
| |
| args.result = iterator; |
| break; |
| |
| case EVENT_ARG_INSERT: |
| args.result = resolver.insert(args.uri, args.values); |
| break; |
| |
| case EVENT_ARG_UPDATE: |
| args.result = resolver.update(args.uri, args.values, args.selection, |
| args.selectionArgs); |
| break; |
| |
| case EVENT_ARG_DELETE: |
| args.result = resolver.delete(args.uri, args.selection, args.selectionArgs); |
| break; |
| } |
| |
| // passing the original token value back to the caller |
| // on top of the event values in arg1. |
| Message reply = args.handler.obtainMessage(token); |
| reply.obj = args; |
| reply.arg1 = msg.arg1; |
| |
| if (localLOGV) { |
| Log.d(TAG, "WorkerHandler.handleMsg: msg.arg1=" + msg.arg1 |
| + ", reply.what=" + reply.what); |
| } |
| |
| reply.sendToTarget(); |
| } |
| } |
| |
| public AsyncQueryHandler(ContentResolver cr) { |
| super(); |
| mResolver = new WeakReference<ContentResolver>(cr); |
| synchronized (AsyncQueryHandler.class) { |
| if (sLooper == null) { |
| HandlerThread thread = new HandlerThread("AsyncQueryWorker"); |
| thread.start(); |
| |
| sLooper = thread.getLooper(); |
| } |
| } |
| mWorkerThreadHandler = createHandler(sLooper); |
| } |
| |
| protected Handler createHandler(Looper looper) { |
| return new WorkerHandler(looper); |
| } |
| |
| /** |
| * This method begins an asynchronous query. When the query is done |
| * {@link #onQueryComplete} is called. |
| * |
| * @param token A token passed into {@link #onQueryComplete} to identify |
| * the query. |
| * @param cookie An object that gets passed into {@link #onQueryComplete} |
| * @param uri The URI, using the content:// scheme, for the content to |
| * retrieve. |
| * @param projection A list of which columns to return. Passing null will |
| * return all columns, which is discouraged to prevent reading data |
| * from storage that isn't going to be used. |
| * @param selection A filter declaring which rows to return, formatted as an |
| * SQL WHERE clause (excluding the WHERE itself). Passing null will |
| * return all rows for the given URI. |
| * @param selectionArgs You may include ?s in selection, which will be |
| * replaced by the values from selectionArgs, in the order that they |
| * appear in the selection. The values will be bound as Strings. |
| * @param orderBy How to order the rows, formatted as an SQL ORDER BY |
| * clause (excluding the ORDER BY itself). Passing null will use the |
| * default sort order, which may be unordered. |
| */ |
| public void startQuery(int token, Object cookie, Uri uri, |
| String[] projection, String selection, String[] selectionArgs, |
| String orderBy) { |
| // Use the token as what so cancelOperations works properly |
| Message msg = mWorkerThreadHandler.obtainMessage(token); |
| msg.arg1 = EVENT_ARG_QUERY; |
| |
| WorkerArgs args = new WorkerArgs(); |
| args.handler = this; |
| args.uri = uri; |
| args.projection = projection; |
| args.selection = selection; |
| args.selectionArgs = selectionArgs; |
| args.orderBy = orderBy; |
| args.cookie = cookie; |
| msg.obj = args; |
| |
| mWorkerThreadHandler.sendMessage(msg); |
| } |
| |
| /** |
| * This method begins an asynchronous query for an {@link EntityIterator}. |
| * When the query is done {@link #onQueryEntitiesComplete} is called. |
| * |
| * @param token A token passed into {@link #onQueryComplete} to identify the |
| * query. |
| * @param cookie An object that gets passed into {@link #onQueryComplete} |
| * @param uri The URI, using the content:// scheme, for the content to |
| * retrieve. |
| * @param selection A filter declaring which rows to return, formatted as an |
| * SQL WHERE clause (excluding the WHERE itself). Passing null |
| * will return all rows for the given URI. |
| * @param selectionArgs You may include ?s in selection, which will be |
| * replaced by the values from selectionArgs, in the order that |
| * they appear in the selection. The values will be bound as |
| * Strings. |
| * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause |
| * (excluding the ORDER BY itself). Passing null will use the |
| * default sort order, which may be unordered. |
| */ |
| public void startQueryEntities(int token, Object cookie, Uri uri, String selection, |
| String[] selectionArgs, String orderBy) { |
| // Use the token as what so cancelOperations works properly |
| Message msg = mWorkerThreadHandler.obtainMessage(token); |
| msg.arg1 = EVENT_ARG_QUERY_ENTITIES; |
| |
| WorkerArgs args = new WorkerArgs(); |
| args.handler = this; |
| args.uri = uri; |
| args.selection = selection; |
| args.selectionArgs = selectionArgs; |
| args.orderBy = orderBy; |
| args.cookie = cookie; |
| msg.obj = args; |
| |
| mWorkerThreadHandler.sendMessage(msg); |
| } |
| |
| /** |
| * Attempts to cancel operation that has not already started. Note that |
| * there is no guarantee that the operation will be canceled. They still may |
| * result in a call to on[Query/Insert/Update/Delete]Complete after this |
| * call has completed. |
| * |
| * @param token The token representing the operation to be canceled. |
| * If multiple operations have the same token they will all be canceled. |
| */ |
| public final void cancelOperation(int token) { |
| mWorkerThreadHandler.removeMessages(token); |
| } |
| |
| /** |
| * This method begins an asynchronous insert. When the insert operation is |
| * done {@link #onInsertComplete} is called. |
| * |
| * @param token A token passed into {@link #onInsertComplete} to identify |
| * the insert operation. |
| * @param cookie An object that gets passed into {@link #onInsertComplete} |
| * @param uri the Uri passed to the insert operation. |
| * @param initialValues the ContentValues parameter passed to the insert operation. |
| */ |
| public final void startInsert(int token, Object cookie, Uri uri, |
| ContentValues initialValues) { |
| // Use the token as what so cancelOperations works properly |
| Message msg = mWorkerThreadHandler.obtainMessage(token); |
| msg.arg1 = EVENT_ARG_INSERT; |
| |
| WorkerArgs args = new WorkerArgs(); |
| args.handler = this; |
| args.uri = uri; |
| args.cookie = cookie; |
| args.values = initialValues; |
| msg.obj = args; |
| |
| mWorkerThreadHandler.sendMessage(msg); |
| } |
| |
| /** |
| * This method begins an asynchronous update. When the update operation is |
| * done {@link #onUpdateComplete} is called. |
| * |
| * @param token A token passed into {@link #onUpdateComplete} to identify |
| * the update operation. |
| * @param cookie An object that gets passed into {@link #onUpdateComplete} |
| * @param uri the Uri passed to the update operation. |
| * @param values the ContentValues parameter passed to the update operation. |
| */ |
| public final void startUpdate(int token, Object cookie, Uri uri, |
| ContentValues values, String selection, String[] selectionArgs) { |
| // Use the token as what so cancelOperations works properly |
| Message msg = mWorkerThreadHandler.obtainMessage(token); |
| msg.arg1 = EVENT_ARG_UPDATE; |
| |
| WorkerArgs args = new WorkerArgs(); |
| args.handler = this; |
| args.uri = uri; |
| args.cookie = cookie; |
| args.values = values; |
| args.selection = selection; |
| args.selectionArgs = selectionArgs; |
| msg.obj = args; |
| |
| mWorkerThreadHandler.sendMessage(msg); |
| } |
| |
| /** |
| * This method begins an asynchronous delete. When the delete operation is |
| * done {@link #onDeleteComplete} is called. |
| * |
| * @param token A token passed into {@link #onDeleteComplete} to identify |
| * the delete operation. |
| * @param cookie An object that gets passed into {@link #onDeleteComplete} |
| * @param uri the Uri passed to the delete operation. |
| * @param selection the where clause. |
| */ |
| public final void startDelete(int token, Object cookie, Uri uri, |
| String selection, String[] selectionArgs) { |
| // Use the token as what so cancelOperations works properly |
| Message msg = mWorkerThreadHandler.obtainMessage(token); |
| msg.arg1 = EVENT_ARG_DELETE; |
| |
| WorkerArgs args = new WorkerArgs(); |
| args.handler = this; |
| args.uri = uri; |
| args.cookie = cookie; |
| args.selection = selection; |
| args.selectionArgs = selectionArgs; |
| msg.obj = args; |
| |
| mWorkerThreadHandler.sendMessage(msg); |
| } |
| |
| /** |
| * Called when an asynchronous query is completed. |
| * |
| * @param token the token to identify the query, passed in from |
| * {@link #startQuery}. |
| * @param cookie the cookie object passed in from {@link #startQuery}. |
| * @param cursor The cursor holding the results from the query. |
| */ |
| protected void onQueryComplete(int token, Object cookie, Cursor cursor) { |
| // Empty |
| } |
| |
| /** |
| * Called when an asynchronous query is completed. |
| * |
| * @param token The token to identify the query. |
| * @param cookie The cookie object. |
| * @param iterator The iterator holding the query results. |
| */ |
| protected void onQueryEntitiesComplete(int token, Object cookie, EntityIterator iterator) { |
| // Empty |
| } |
| |
| /** |
| * Called when an asynchronous insert is completed. |
| * |
| * @param token the token to identify the query, passed in from |
| * {@link #startInsert}. |
| * @param cookie the cookie object that's passed in from |
| * {@link #startInsert}. |
| * @param uri the uri returned from the insert operation. |
| */ |
| protected void onInsertComplete(int token, Object cookie, Uri uri) { |
| // Empty |
| } |
| |
| /** |
| * Called when an asynchronous update is completed. |
| * |
| * @param token the token to identify the query, passed in from |
| * {@link #startUpdate}. |
| * @param cookie the cookie object that's passed in from |
| * {@link #startUpdate}. |
| * @param result the result returned from the update operation |
| */ |
| protected void onUpdateComplete(int token, Object cookie, int result) { |
| // Empty |
| } |
| |
| /** |
| * Called when an asynchronous delete is completed. |
| * |
| * @param token the token to identify the query, passed in from |
| * {@link #startDelete}. |
| * @param cookie the cookie object that's passed in from |
| * {@link #startDelete}. |
| * @param result the result returned from the delete operation |
| */ |
| protected void onDeleteComplete(int token, Object cookie, int result) { |
| // Empty |
| } |
| |
| @Override |
| public void handleMessage(Message msg) { |
| WorkerArgs args = (WorkerArgs) msg.obj; |
| |
| if (localLOGV) { |
| Log.d(TAG, "AsyncQueryHandler.handleMessage: msg.what=" + msg.what |
| + ", msg.arg1=" + msg.arg1); |
| } |
| |
| int token = msg.what; |
| int event = msg.arg1; |
| |
| // pass token back to caller on each callback. |
| switch (event) { |
| case EVENT_ARG_QUERY: |
| onQueryComplete(token, args.cookie, (Cursor) args.result); |
| break; |
| |
| case EVENT_ARG_QUERY_ENTITIES: |
| onQueryEntitiesComplete(token, args.cookie, (EntityIterator)args.result); |
| break; |
| |
| case EVENT_ARG_INSERT: |
| onInsertComplete(token, args.cookie, (Uri) args.result); |
| break; |
| |
| case EVENT_ARG_UPDATE: |
| onUpdateComplete(token, args.cookie, (Integer) args.result); |
| break; |
| |
| case EVENT_ARG_DELETE: |
| onDeleteComplete(token, args.cookie, (Integer) args.result); |
| break; |
| } |
| } |
| } |