The file containing the source code shown below is located in the corresponding directory in <sdk>/samples/android-<version>/...
/*
* Copyright (C) 2011 The Android开源工程
*
* 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 com.example.android.musicplayer;
import android.app.PendingIntent;
import android.graphics.Bitmap;
import android.os.Looper;
import android.util.Log;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
/**
* RemoteControlClient enables exposing information meant to be consumed by remote controls capable
* of displaying metadata, artwork and media transport control buttons. A remote control client
* object is associated with a media button event receiver. This event receiver must have been
* previously registered with
* {@link android.media.AudioManager#registerMediaButtonEventReceiver(android.content.ComponentName)}
* before the RemoteControlClient can be registered through
* {@link android.media.AudioManager#registerRemoteControlClient(android.media.RemoteControlClient)}.
*/
@SuppressWarnings({"rawtypes", "unchecked"})
public class RemoteControlClientCompat {
private static final String TAG = "RemoteControlCompat";
private static Class sRemoteControlClientClass;
// RCC short for RemoteControlClient
private static Method sRCCEditMetadataMethod;
private static Method sRCCSetPlayStateMethod;
private static Method sRCCSetTransportControlFlags;
private static boolean sHasRemoteControlAPIs = false;
static {
try {
ClassLoader classLoader = RemoteControlClientCompat.class.getClassLoader();
sRemoteControlClientClass = getActualRemoteControlClientClass(classLoader);
// dynamically populate the playstate and flag values in case they change
// in future versions.
for (Field field : RemoteControlClientCompat.class.getFields()) {
try {
Field realField = sRemoteControlClientClass.getField(field.getName());
Object realValue = realField.get(null);
field.set(null, realValue);
} catch (NoSuchFieldException e) {
Log.w(TAG, "Could not get real field: " + field.getName());
} catch (IllegalArgumentException e) {
Log.w(TAG, "Error trying to pull field value for: " + field.getName()
+ " " + e.getMessage());
} catch (IllegalAccessException e) {
Log.w(TAG, "Error trying to pull field value for: " + field.getName()
+ " " + e.getMessage());
}
}
// get the required public methods on RemoteControlClient
sRCCEditMetadataMethod = sRemoteControlClientClass.getMethod("editMetadata",
boolean.class);
sRCCSetPlayStateMethod = sRemoteControlClientClass.getMethod("setPlaybackState",
int.class);
sRCCSetTransportControlFlags = sRemoteControlClientClass.getMethod(
"setTransportControlFlags", int.class);
sHasRemoteControlAPIs = true;
} catch (ClassNotFoundException e) {
// Silently fail when running on an OS before ICS.
} catch (NoSuchMethodException e) {
// Silently fail when running on an OS before ICS.
} catch (IllegalArgumentException e) {
// Silently fail when running on an OS before ICS.
} catch (SecurityException e) {
// Silently fail when running on an OS before ICS.
}
}
public static Class getActualRemoteControlClientClass(ClassLoader classLoader)
throws ClassNotFoundException {
return classLoader.loadClass("android.media.RemoteControlClient");
}
private Object mActualRemoteControlClient;
public RemoteControlClientCompat(PendingIntent pendingIntent) {
if (!sHasRemoteControlAPIs) {
return;
}
try {
mActualRemoteControlClient =
sRemoteControlClientClass.getConstructor(PendingIntent.class)
.newInstance(pendingIntent);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
public RemoteControlClientCompat(PendingIntent pendingIntent, Looper looper) {
if (!sHasRemoteControlAPIs) {
return;
}
try {
mActualRemoteControlClient =
sRemoteControlClientClass.getConstructor(PendingIntent.class, Looper.class)
.newInstance(pendingIntent, looper);
} catch (Exception e) {
Log.e(TAG, "Error creating new instance of " + sRemoteControlClientClass.getName(), e);
}
}
/**
* Class used to modify metadata in a {@link android.media.RemoteControlClient} object. Use
* {@link android.media.RemoteControlClient#editMetadata(boolean)} to create an instance of an
* editor, on which you set the metadata for the RemoteControlClient instance. Once all the
* information has been set, use {@link #apply()} to make it the new metadata that should be
* displayed for the associated client. Once the metadata has been "applied", you cannot reuse
* this instance of the MetadataEditor.
*/
public class MetadataEditorCompat {
private Method mPutStringMethod;
private Method mPutBitmapMethod;
private Method mPutLongMethod;
private Method mClearMethod;
private Method mApplyMethod;
private Object mActualMetadataEditor;
/**
* The metadata key for the content artwork / album art.
*/
public final static int METADATA_KEY_ARTWORK = 100;
private MetadataEditorCompat(Object actualMetadataEditor) {
if (sHasRemoteControlAPIs && actualMetadataEditor == null) {
throw new IllegalArgumentException("Remote Control API's exist, " +
"should not be given a null MetadataEditor");
}
if (sHasRemoteControlAPIs) {
Class metadataEditorClass = actualMetadataEditor.getClass();
try {
mPutStringMethod = metadataEditorClass.getMethod("putString",
int.class, String.class);
mPutBitmapMethod = metadataEditorClass.getMethod("putBitmap",
int.class, Bitmap.class);
mPutLongMethod = metadataEditorClass.getMethod("putLong",
int.class, long.class);
mClearMethod = metadataEditorClass.getMethod("clear", new Class[]{});
mApplyMethod = metadataEditorClass.getMethod("apply", new Class[]{});
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}
mActualMetadataEditor = actualMetadataEditor;
}
/**
* Adds textual information to be displayed.
* Note that none of the information added after {@link #apply()} has been called,
* will be displayed.
* @param key The identifier of a the metadata field to set. Valid values are
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_ALBUM},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_ALBUMARTIST},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_TITLE},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_ARTIST},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_AUTHOR},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_COMPILATION},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_COMPOSER},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_DATE},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_GENRE},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_TITLE},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_WRITER}.
* @param value The text for the given key, or {@code null} to signify there is no valid
* information for the field.
* @return Returns a reference to the same MetadataEditor object, so you can chain put
* calls together.
*/
public MetadataEditorCompat putString(int key, String value) {
if (sHasRemoteControlAPIs) {
try {
mPutStringMethod.invoke(mActualMetadataEditor, key, value);
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}
return this;
}
/**
* Sets the album / artwork picture to be displayed on the remote control.
* @param key the identifier of the bitmap to set. The only valid value is
* {@link #METADATA_KEY_ARTWORK}
* @param bitmap The bitmap for the artwork, or null if there isn't any.
* @return Returns a reference to the same MetadataEditor object, so you can chain put
* calls together.
* @throws IllegalArgumentException
* @see android.graphics.Bitmap
*/
public MetadataEditorCompat putBitmap(int key, Bitmap bitmap) {
if (sHasRemoteControlAPIs) {
try {
mPutBitmapMethod.invoke(mActualMetadataEditor, key, bitmap);
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}
return this;
}
/**
* Adds numerical information to be displayed.
* Note that none of the information added after {@link #apply()} has been called,
* will be displayed.
* @param key the identifier of a the metadata field to set. Valid values are
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_CD_TRACK_NUMBER},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_DISC_NUMBER},
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_DURATION} (with a value
* expressed in milliseconds),
* {@link android.media.MediaMetadataRetriever#METADATA_KEY_YEAR}.
* @param value The long value for the given key
* @return Returns a reference to the same MetadataEditor object, so you can chain put
* calls together.
* @throws IllegalArgumentException
*/
public MetadataEditorCompat putLong(int key, long value) {
if (sHasRemoteControlAPIs) {
try {
mPutLongMethod.invoke(mActualMetadataEditor, key, value);
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}
return this;
}
/**
* Clears all the metadata that has been set since the MetadataEditor instance was
* created with {@link android.media.RemoteControlClient#editMetadata(boolean)}.
*/
public void clear() {
if (sHasRemoteControlAPIs) {
try {
mClearMethod.invoke(mActualMetadataEditor, (Object[]) null);
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}
}
/**
* Associates all the metadata that has been set since the MetadataEditor instance was
* created with {@link android.media.RemoteControlClient#editMetadata(boolean)}, or since
* {@link #clear()} was called, with the RemoteControlClient. Once "applied", this
* MetadataEditor cannot be reused to edit the RemoteControlClient's metadata.
*/
public void apply() {
if (sHasRemoteControlAPIs) {
try {
mApplyMethod.invoke(mActualMetadataEditor, (Object[]) null);
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}
}
}
/**
* Creates a {@link android.media.RemoteControlClient.MetadataEditor}.
* @param startEmpty Set to false if you want the MetadataEditor to contain the metadata that
* was previously applied to the RemoteControlClient, or true if it is to be created empty.
* @return a new MetadataEditor instance.
*/
public MetadataEditorCompat editMetadata(boolean startEmpty) {
Object metadataEditor;
if (sHasRemoteControlAPIs) {
try {
metadataEditor = sRCCEditMetadataMethod.invoke(mActualRemoteControlClient,
startEmpty);
} catch (Exception e) {
throw new RuntimeException(e);
}
} else {
metadataEditor = null;
}
return new MetadataEditorCompat(metadataEditor);
}
/**
* Sets the current playback state.
* @param state The current playback state, one of the following values:
* {@link android.media.RemoteControlClient#PLAYSTATE_STOPPED},
* {@link android.media.RemoteControlClient#PLAYSTATE_PAUSED},
* {@link android.media.RemoteControlClient#PLAYSTATE_PLAYING},
* {@link android.media.RemoteControlClient#PLAYSTATE_FAST_FORWARDING},
* {@link android.media.RemoteControlClient#PLAYSTATE_REWINDING},
* {@link android.media.RemoteControlClient#PLAYSTATE_SKIPPING_FORWARDS},
* {@link android.media.RemoteControlClient#PLAYSTATE_SKIPPING_BACKWARDS},
* {@link android.media.RemoteControlClient#PLAYSTATE_BUFFERING},
* {@link android.media.RemoteControlClient#PLAYSTATE_ERROR}.
*/
public void setPlaybackState(int state) {
if (sHasRemoteControlAPIs) {
try {
sRCCSetPlayStateMethod.invoke(mActualRemoteControlClient, state);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
/**
* Sets the flags for the media transport control buttons that this client supports.
* @param transportControlFlags A combination of the following flags:
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_PREVIOUS},
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_REWIND},
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_PLAY},
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_PLAY_PAUSE},
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_PAUSE},
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_STOP},
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_FAST_FORWARD},
* {@link android.media.RemoteControlClient#FLAG_KEY_MEDIA_NEXT}
*/
public void setTransportControlFlags(int transportControlFlags) {
if (sHasRemoteControlAPIs) {
try {
sRCCSetTransportControlFlags.invoke(mActualRemoteControlClient,
transportControlFlags);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
public final Object getActualRemoteControlClientObject() {
return mActualRemoteControlClient;
}
}