Android 4.1 Music 通知栏的音乐控制

本文根据原生Android 4.1.1 Music 源码做修改。

1 原生Music 暂停的时候，会删除通知栏上的通知。

2 原生Music 通知栏不能控制音乐，比如下一首，上一首，暂停/播放。

一 解决思路：

1 接到暂停广播时，只暂停，不去除通知。

/packages/apps/Music/src/com/android/music/MediaPlaybackService.java中

调用的 stopForeground(true)方法控制去除通知

2 自定义音乐通知，添加按钮事件。

   /packages/apps/Music/src/com/android/music/MediaPlaybackService.java中

  updateNotification()方法中自定义Notification,关键对RemoteViews 的理解

二  修改后效果图：

三 详细代码

1 接到暂停广播时，只暂停，不去除通知

源代码 采取的策略是 只要暂停就去除通知，这就会造成一个问题就是，当播放视频的时候音乐播放器接受到暂停的广播，于是消除了通知栏。

1.1 添加暂停 不消除通知的方法 pause(boolean isStopForeground)

private void pause(boolean isStopForeground) {
        synchronized(this) {
            mMediaplayerHandler.removeMessages(FADEUP);
            if (isPlaying()) {
                mPlayer.pause();
                gotoIdleState(isStopForeground);
                mIsSupposedToBePlaying = false;
                notifyChange(PLAYSTATE_CHANGED);
                saveBookmarkIfNeeded();
            }
        }
    }

    private void gotoIdleState(boolean isStopForeground) {
        mDelayedStopHandler.removeCallbacksAndMessages(null);
        Message msg = mDelayedStopHandler.obtainMessage();
        mDelayedStopHandler.sendMessageDelayed(msg, IDLE_DELAY);
       //此方法控制消除通知
        stopForeground(isStopForeground);
    }

1.2 接收暂停广播的时候将pause()方法换为：pause(false)

private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            String cmd = intent.getStringExtra("command");
            MusicUtils.debugLog("mIntentReceiver.onReceive " + action + " / " + cmd);
            if (CMDNEXT.equals(cmd) || NEXT_ACTION.equals(action)) {
                gotoNext(true);
            } else if (CMDPREVIOUS.equals(cmd) || PREVIOUS_ACTION.equals(action)) {
                prev();
            } else if (CMDTOGGLEPAUSE.equals(cmd) || TOGGLEPAUSE_ACTION.equals(action)) {
                if (isPlaying()) {
                    /*Begin: modified  */
                    pause(false);
                    updateNotification();
                    /*End: */
                    mPausedByTransientLossOfFocus = false;
                } else {
                    play();
                }
            } else if (CMDPAUSE.equals(cmd) || PAUSE_ACTION.equals(action)) {
                /*Begin: modified  */
                pause(false);
                updateNotification();
                /*End:*/
                mPausedByTransientLossOfFocus = false;
            } else if (CMDPLAY.equals(cmd)) {
                              ...

2 Music 音乐通知控制 

2.1 通知的布局文件 /packages/apps/Music/res/layout/statusbar.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal" >

    <LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_gravity="center_vertical">
        <!-- 图标 -->
        <ImageView
            android:id="@+id/icon"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:padding="4dip" >
        </ImageView>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal" >
              <!-- 音乐名 -->
            <TextView
                android:id="@+id/trackname"
                style="@android:style/TextAppearance.StatusBar.EventContent.Title"
                android:layout_width="80dip"
                android:layout_height="wrap_content"
                android:layout_gravity="left"
                android:ellipsize="marquee"
                android:focusable="true"
                android:singleLine="true" />

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent" >
                  <!-- 上一首 -->
                <ImageButton
                    android:id="@+id/statusbar_prev"
                    style="@android:style/MediaButton.Previous"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentLeft="true" />
                  <!-- 暂停/播放 -->
                <ImageButton
                    android:id="@+id/statusbar_pause"
                    style="@android:style/MediaButton.Pause"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_centerHorizontal="true" />
                  <!-- 下一首 -->
                <ImageButton
                    android:id="@+id/statusbar_next"
                    style="@android:style/MediaButton.Next"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentRight="true"
                    android:gravity="right" />
            </RelativeLayout>
        </LinearLayout>
         <!-- 专辑信息，歌手 -->
        <TextView
            android:id="@+id/artistalbum"
            style="@android:style/TextAppearance.StatusBar.EventContent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="left"
            android:ellipsize="end"
            android:maxLines="2"
            android:scrollHorizontally="true" />
    </LinearLayout>

</LinearLayout>

2.2  通知栏控制：

/packages/apps/Music/src/com/android/music/MediaPlaybackService.java中

 updateNotification（）为发送的通知代码，在这里面修改

private void updateNotification() {
        //RemoteViews未自定义布局，   R.layout.statusbar 为通知的布局文件
        RemoteViews views = new RemoteViews(getPackageName(), R.layout.statusbar);
        views.setImageViewResource(R.id.icon, R.drawable.stat_notify_musicplayer);
        if (getAudioId() < 0) {
            // streaming
            views.setTextViewText(R.id.trackname, getPath());
            views.setTextViewText(R.id.artistalbum, null);
        } else {
            String artist = getArtistName();
            views.setTextViewText(R.id.trackname, getTrackName());
            if (artist == null || artist.equals(MediaStore.UNKNOWN_STRING)) {
                artist = getString(R.string.unknown_artist_name);
            }
            String album = getAlbumName();
            if (album == null || album.equals(MediaStore.UNKNOWN_STRING)) {
                album = getString(R.string.unknown_album_name);
            }

            views.setTextViewText(R.id.artistalbum,
                    getString(R.string.notification_artist_album, artist, album)
                    );
        }
        Notification status = new Notification();
        /*Begin: modified 添加修改代码*/
        //status_icon 为状态栏图标,R.id.statusbar_pause 为通知 的 暂停/开始按钮
        int status_icon = R.drawable.ic_appwidget_music_play;
        //根据播放状态，来决定 暂停/开始 图标
        if(isPlaying()){
            views.setImageViewResource(R.id.statusbar_pause, R.drawable.ic_appwidget_music_pause);
        }else{
            views.setImageViewResource(R.id.statusbar_pause, R.drawable.ic_appwidget_music_play);
            status_icon = R.drawable.ic_appwidget_music_pause;
         }
         // 给通知栏 上一首 按钮 添加点击事件
        views.setOnClickPendingIntent(R.id.statusbar_prev, pre_PendingIntent());
        //给通知栏 暂停/开始 按钮 添加点击事件
        views.setOnClickPendingIntent(R.id.statusbar_pause, pause_PendingIntent());
        //给通知栏 下一首 按钮 添加点击事件
        views.setOnClickPendingIntent(R.id.statusbar_next, next_PendingIntent());
        /*End:  */

        status.contentView = views;
        status.flags |= Notification.FLAG_ONGOING_EVENT;
        status.icon = status_icon;
        status.contentIntent = PendingIntent.getActivity(this, 0,
                new Intent("com.android.music.PLAYBACK_VIEWER")
                .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK), 0);
        startForeground(PLAYBACKSERVICE_STATUS, status);
    }

添加的点击事件函数：

/*Begin:  modify  利用MediaPlaybackService 现有的广播监听 实现播放控制 */
    //上一首，
    private PendingIntent pre_PendingIntent(){
        Intent intent = new Intent(PREVIOUS_ACTION);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);
         return pendingIntent;
    }
    //暂停开始
    private PendingIntent pause_PendingIntent(){
        Intent intent = new Intent(TOGGLEPAUSE_ACTION);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);
         return pendingIntent;
    }
    //下一首
    private PendingIntent next_PendingIntent(){
        Intent intent = new Intent(NEXT_ACTION);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);
         return pendingIntent;
    }

    /*end:  */

为了实现暂停/开始按钮通知栏图标显示与音乐播放 的一致 改了以下两个地方：

其一 play()  方法中 将  updateNotification() 放在了

if (!mIsSupposedToBePlaying) {
                mIsSupposedToBePlaying = true;
                notifyChange(PLAYSTATE_CHANGED);
            }

之后

public void play() {
            ...
if (!mIsSupposedToBePlaying) {
                mIsSupposedToBePlaying = true;
                notifyChange(PLAYSTATE_CHANGED);
            }
updateNotification();
          ...
}

其二：当接受到 暂停/开始  事件的 广播后，如果 暂停音乐，则调用updateNotification()更新方法

private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
       @Override
       public void onReceive(Context context, Intent intent) {
           String action = intent.getAction();
           String cmd = intent.getStringExtra("command");
           MusicUtils.debugLog("mIntentReceiver.onReceive " + action + " / " + cmd);
           Log.e(LOGTAG, "  mIntentReceiver   action = "+action+"   cmd ="+cmd+"===");
           if (CMDNEXT.equals(cmd) || NEXT_ACTION.equals(action)) {
               gotoNext(true);
           } else if (CMDPREVIOUS.equals(cmd) || PREVIOUS_ACTION.equals(action)) {
               prev();
           } else if (CMDTOGGLEPAUSE.equals(cmd) || TOGGLEPAUSE_ACTION.equals(action)) {
               if (isPlaying()) {
                   /*Begin: 开始修改*/
                  // pause(false); 暂停时不消除通知栏
                   pause(false);
                   updateNotification();
                   /*End: modified*/
                   mPausedByTransientLossOfFocus = false;
               } else {
                   play();
               }
                               ...