| /* |
| * 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.database; |
| |
| import android.os.Handler; |
| |
| /** |
| * Receives call backs for changes to content. Must be implemented by objects which are added |
| * to a {@link ContentObservable}. |
| */ |
| public abstract class ContentObserver { |
| |
| private Transport mTransport; |
| |
| // Protects mTransport |
| private Object lock = new Object(); |
| |
| /* package */ Handler mHandler; |
| |
| private final class NotificationRunnable implements Runnable { |
| |
| private boolean mSelf; |
| |
| public NotificationRunnable(boolean self) { |
| mSelf = self; |
| } |
| |
| public void run() { |
| ContentObserver.this.onChange(mSelf); |
| } |
| } |
| |
| private static final class Transport extends IContentObserver.Stub { |
| ContentObserver mContentObserver; |
| |
| public Transport(ContentObserver contentObserver) { |
| mContentObserver = contentObserver; |
| } |
| |
| public boolean deliverSelfNotifications() { |
| ContentObserver contentObserver = mContentObserver; |
| if (contentObserver != null) { |
| return contentObserver.deliverSelfNotifications(); |
| } |
| return false; |
| } |
| |
| public void onChange(boolean selfChange) { |
| ContentObserver contentObserver = mContentObserver; |
| if (contentObserver != null) { |
| contentObserver.dispatchChange(selfChange); |
| } |
| } |
| |
| public void releaseContentObserver() { |
| mContentObserver = null; |
| } |
| } |
| |
| /** |
| * onChange() will happen on the provider Handler. |
| * |
| * @param handler The handler to run {@link #onChange} on. |
| */ |
| public ContentObserver(Handler handler) { |
| mHandler = handler; |
| } |
| |
| /** |
| * Gets access to the binder transport object. Not for public consumption. |
| * |
| * {@hide} |
| */ |
| public IContentObserver getContentObserver() { |
| synchronized(lock) { |
| if (mTransport == null) { |
| mTransport = new Transport(this); |
| } |
| return mTransport; |
| } |
| } |
| |
| /** |
| * Gets access to the binder transport object, and unlinks the transport object |
| * from the ContentObserver. Not for public consumption. |
| * |
| * {@hide} |
| */ |
| public IContentObserver releaseContentObserver() { |
| synchronized(lock) { |
| Transport oldTransport = mTransport; |
| if (oldTransport != null) { |
| oldTransport.releaseContentObserver(); |
| mTransport = null; |
| } |
| return oldTransport; |
| } |
| } |
| |
| /** |
| * Returns true if this observer is interested in notifications for changes |
| * made through the cursor the observer is registered with. |
| */ |
| public boolean deliverSelfNotifications() { |
| return false; |
| } |
| |
| /** |
| * This method is called when a change occurs to the cursor that |
| * is being observed. |
| * |
| * @param selfChange true if the update was caused by a call to <code>commit</code> on the |
| * cursor that is being observed. |
| */ |
| public void onChange(boolean selfChange) {} |
| |
| public final void dispatchChange(boolean selfChange) { |
| if (mHandler == null) { |
| onChange(selfChange); |
| } else { |
| mHandler.post(new NotificationRunnable(selfChange)); |
| } |
| } |
| } |