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