/* * Copyright (C) 2014 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.service.media; import android.annotation.NonNull; import android.annotation.Nullable; import android.annotation.SdkConstant; import android.annotation.SdkConstant.SdkConstantType; import android.app.Service; import android.content.Intent; import android.content.pm.PackageManager; import android.content.pm.ParceledListSlice; import android.media.browse.MediaBrowser; import android.media.session.MediaSession; import android.os.Binder; import android.os.Bundle; import android.os.IBinder; import android.os.Handler; import android.os.RemoteException; import android.os.ResultReceiver; import android.service.media.IMediaBrowserService; import android.service.media.IMediaBrowserServiceCallbacks; import android.text.TextUtils; import android.util.ArrayMap; import android.util.Log; import java.io.FileDescriptor; import java.io.PrintWriter; import java.util.HashSet; import java.util.List; /** * Base class for media browse services. *

* Media browse services enable applications to browse media content provided by an application * and ask the application to start playing it. They may also be used to control content that * is already playing by way of a {@link MediaSession}. *

* * To extend this class, you must declare the service in your manifest file with * an intent filter with the {@link #SERVICE_INTERFACE} action. * * For example: *

 * <service android:name=".MyMediaBrowserService"
 *          android:label="@string/service_name" >
 *     <intent-filter>
 *         <action android:name="android.media.browse.MediaBrowserService" />
 *     </intent-filter>
 * </service>
 * 
* */ public abstract class MediaBrowserService extends Service { private static final String TAG = "MediaBrowserService"; private static final boolean DBG = false; /** * The {@link Intent} that must be declared as handled by the service. */ @SdkConstant(SdkConstantType.SERVICE_ACTION) public static final String SERVICE_INTERFACE = "android.media.browse.MediaBrowserService"; /** * A key for passing the MediaItem to the ResultReceiver in getItem. * * @hide */ public static final String KEY_MEDIA_ITEM = "media_item"; private final ArrayMap mConnections = new ArrayMap(); private final Handler mHandler = new Handler(); private ServiceBinder mBinder; MediaSession.Token mSession; /** * All the info about a connection. */ private class ConnectionRecord { String pkg; Bundle rootHints; IMediaBrowserServiceCallbacks callbacks; BrowserRoot root; HashSet subscriptions = new HashSet(); } /** * Completion handler for asynchronous callback methods in {@link MediaBrowserService}. *

* Each of the methods that takes one of these to send the result must call * {@link #sendResult} to respond to the caller with the given results. If those * functions return without calling {@link #sendResult}, they must instead call * {@link #detach} before returning, and then may call {@link #sendResult} when * they are done. If more than one of those methods is called, an exception will * be thrown. * * @see MediaBrowserService#onLoadChildren * @see MediaBrowserService#onGetMediaItem */ public class Result { private Object mDebug; private boolean mDetachCalled; private boolean mSendResultCalled; Result(Object debug) { mDebug = debug; } /** * Send the result back to the caller. */ public void sendResult(T result) { if (mSendResultCalled) { throw new IllegalStateException("sendResult() called twice for: " + mDebug); } mSendResultCalled = true; onResultSent(result); } /** * Detach this message from the current thread and allow the {@link #sendResult} * call to happen later. */ public void detach() { if (mDetachCalled) { throw new IllegalStateException("detach() called when detach() had already" + " been called for: " + mDebug); } if (mSendResultCalled) { throw new IllegalStateException("detach() called when sendResult() had already" + " been called for: " + mDebug); } mDetachCalled = true; } boolean isDone() { return mDetachCalled || mSendResultCalled; } /** * Called when the result is sent, after assertions about not being called twice * have happened. */ void onResultSent(T result) { } } private class ServiceBinder extends IMediaBrowserService.Stub { @Override public void connect(final String pkg, final Bundle rootHints, final IMediaBrowserServiceCallbacks callbacks) { final int uid = Binder.getCallingUid(); if (!isValidPackage(pkg, uid)) { throw new IllegalArgumentException("Package/uid mismatch: uid=" + uid + " package=" + pkg); } mHandler.post(new Runnable() { @Override public void run() { final IBinder b = callbacks.asBinder(); // Clear out the old subscriptions. We are getting new ones. mConnections.remove(b); final ConnectionRecord connection = new ConnectionRecord(); connection.pkg = pkg; connection.rootHints = rootHints; connection.callbacks = callbacks; connection.root = MediaBrowserService.this.onGetRoot(pkg, uid, rootHints); // If they didn't return something, don't allow this client. if (connection.root == null) { Log.i(TAG, "No root for client " + pkg + " from service " + getClass().getName()); try { callbacks.onConnectFailed(); } catch (RemoteException ex) { Log.w(TAG, "Calling onConnectFailed() failed. Ignoring. " + "pkg=" + pkg); } } else { try { mConnections.put(b, connection); if (mSession != null) { callbacks.onConnect(connection.root.getRootId(), mSession, connection.root.getExtras()); } } catch (RemoteException ex) { Log.w(TAG, "Calling onConnect() failed. Dropping client. " + "pkg=" + pkg); mConnections.remove(b); } } } }); } @Override public void disconnect(final IMediaBrowserServiceCallbacks callbacks) { mHandler.post(new Runnable() { @Override public void run() { final IBinder b = callbacks.asBinder(); // Clear out the old subscriptions. We are getting new ones. final ConnectionRecord old = mConnections.remove(b); if (old != null) { // TODO } } }); } @Override public void addSubscription(final String id, final IMediaBrowserServiceCallbacks callbacks) { mHandler.post(new Runnable() { @Override public void run() { final IBinder b = callbacks.asBinder(); // Get the record for the connection final ConnectionRecord connection = mConnections.get(b); if (connection == null) { Log.w(TAG, "addSubscription for callback that isn't registered id=" + id); return; } MediaBrowserService.this.addSubscription(id, connection); } }); } @Override public void removeSubscription(final String id, final IMediaBrowserServiceCallbacks callbacks) { mHandler.post(new Runnable() { @Override public void run() { final IBinder b = callbacks.asBinder(); ConnectionRecord connection = mConnections.get(b); if (connection == null) { Log.w(TAG, "removeSubscription for callback that isn't registered id=" + id); return; } if (!connection.subscriptions.remove(id)) { Log.w(TAG, "removeSubscription called for " + id + " which is not subscribed"); } } }); } @Override public void getMediaItem(final String mediaId, final ResultReceiver receiver) { if (TextUtils.isEmpty(mediaId) || receiver == null) { return; } mHandler.post(new Runnable() { @Override public void run() { performLoadItem(mediaId, receiver); } }); } } @Override public void onCreate() { super.onCreate(); mBinder = new ServiceBinder(); } @Override public IBinder onBind(Intent intent) { if (SERVICE_INTERFACE.equals(intent.getAction())) { return mBinder; } return null; } @Override public void dump(FileDescriptor fd, PrintWriter writer, String[] args) { } /** * Called to get the root information for browsing by a particular client. *

* The implementation should verify that the client package has permission * to access browse media information before returning the root id; it * should return null if the client is not allowed to access this * information. *

* * @param clientPackageName The package name of the application which is * requesting access to browse media. * @param clientUid The uid of the application which is requesting access to * browse media. * @param rootHints An optional bundle of service-specific arguments to send * to the media browse service when connecting and retrieving the * root id for browsing, or null if none. The contents of this * bundle may affect the information returned when browsing. * @return The {@link BrowserRoot} for accessing this app's content or null. */ public abstract @Nullable BrowserRoot onGetRoot(@NonNull String clientPackageName, int clientUid, @Nullable Bundle rootHints); /** * Called to get information about the children of a media item. *

* Implementations must call {@link Result#sendResult result.sendResult} * with the list of children. If loading the children will be an expensive * operation that should be performed on another thread, * {@link Result#detach result.detach} may be called before returning from * this function, and then {@link Result#sendResult result.sendResult} * called when the loading is complete. * * @param parentId The id of the parent media item whose children are to be * queried. * @param result The Result to send the list of children to, or null if the * id is invalid. */ public abstract void onLoadChildren(@NonNull String parentId, @NonNull Result> result); /** * Called to get information about a specific media item. *

* Implementations must call {@link Result#sendResult result.sendResult}. If * loading the item will be an expensive operation {@link Result#detach * result.detach} may be called before returning from this function, and * then {@link Result#sendResult result.sendResult} called when the item has * been loaded. *

* The default implementation sends a null result. * * @param itemId The id for the specific * {@link android.media.browse.MediaBrowser.MediaItem}. * @param result The Result to send the item to, or null if the id is * invalid. */ public void onLoadItem(String itemId, Result result) { result.sendResult(null); } /** * Call to set the media session. *

* This should be called as soon as possible during the service's startup. * It may only be called once. * * @param token The token for the service's {@link MediaSession}. */ public void setSessionToken(final MediaSession.Token token) { if (token == null) { throw new IllegalArgumentException("Session token may not be null."); } if (mSession != null) { throw new IllegalStateException("The session token has already been set."); } mSession = token; mHandler.post(new Runnable() { @Override public void run() { for (IBinder key : mConnections.keySet()) { ConnectionRecord connection = mConnections.get(key); try { connection.callbacks.onConnect(connection.root.getRootId(), token, connection.root.getExtras()); } catch (RemoteException e) { Log.w(TAG, "Connection for " + connection.pkg + " is no longer valid."); mConnections.remove(key); } } } }); } /** * Gets the session token, or null if it has not yet been created * or if it has been destroyed. */ public @Nullable MediaSession.Token getSessionToken() { return mSession; } /** * Notifies all connected media browsers that the children of * the specified parent id have changed in some way. * This will cause browsers to fetch subscribed content again. * * @param parentId The id of the parent media item whose * children changed. */ public void notifyChildrenChanged(@NonNull final String parentId) { if (parentId == null) { throw new IllegalArgumentException("parentId cannot be null in notifyChildrenChanged"); } mHandler.post(new Runnable() { @Override public void run() { for (IBinder binder : mConnections.keySet()) { ConnectionRecord connection = mConnections.get(binder); if (connection.subscriptions.contains(parentId)) { performLoadChildren(parentId, connection); } } } }); } /** * Return whether the given package is one of the ones that is owned by the uid. */ private boolean isValidPackage(String pkg, int uid) { if (pkg == null) { return false; } final PackageManager pm = getPackageManager(); final String[] packages = pm.getPackagesForUid(uid); final int N = packages.length; for (int i=0; i * Callers must make sure that this connection is still connected. */ private void performLoadChildren(final String parentId, final ConnectionRecord connection) { final Result> result = new Result>(parentId) { @Override void onResultSent(List list) { if (list == null) { throw new IllegalStateException("onLoadChildren sent null list for id " + parentId); } if (mConnections.get(connection.callbacks.asBinder()) != connection) { if (DBG) { Log.d(TAG, "Not sending onLoadChildren result for connection that has" + " been disconnected. pkg=" + connection.pkg + " id=" + parentId); } return; } final ParceledListSlice pls = new ParceledListSlice(list); try { connection.callbacks.onLoadChildren(parentId, pls); } catch (RemoteException ex) { // The other side is in the process of crashing. Log.w(TAG, "Calling onLoadChildren() failed for id=" + parentId + " package=" + connection.pkg); } } }; onLoadChildren(parentId, result); if (!result.isDone()) { throw new IllegalStateException("onLoadChildren must call detach() or sendResult()" + " before returning for package=" + connection.pkg + " id=" + parentId); } } private void performLoadItem(String itemId, final ResultReceiver receiver) { final Result result = new Result(itemId) { @Override void onResultSent(MediaBrowser.MediaItem item) { Bundle bundle = new Bundle(); bundle.putParcelable(KEY_MEDIA_ITEM, item); receiver.send(0, bundle); } }; MediaBrowserService.this.onLoadItem(itemId, result); if (!result.isDone()) { throw new IllegalStateException("onLoadItem must call detach() or sendResult()" + " before returning for id=" + itemId); } } /** * Contains information that the browser service needs to send to the client * when first connected. */ public static final class BrowserRoot { final private String mRootId; final private Bundle mExtras; /** * Constructs a browser root. * @param rootId The root id for browsing. * @param extras Any extras about the browser service. */ public BrowserRoot(@NonNull String rootId, @Nullable Bundle extras) { if (rootId == null) { throw new IllegalArgumentException("The root id in BrowserRoot cannot be null. " + "Use null for BrowserRoot instead."); } mRootId = rootId; mExtras = extras; } /** * Gets the root id for browsing. */ public String getRootId() { return mRootId; } /** * Gets any extras about the brwoser service. */ public Bundle getExtras() { return mExtras; } } }