如何使用光标将封面艺术嵌入到音频文件中？

Question

我正在开发一个很小的音频播放器。问题是：在许多问题之后，我设法用从外部存储中的任何文件夹中检索到的歌曲构建了一个 ListView，并用标题、艺术家和专辑名称列出它们。现在我想在 ListView 中添加封面专辑。封面必须取自歌曲音频文件中嵌入的图片。

我尝试使用 MediaMetadataRetriever，但无法获取每个文件的完整 Uri，因此无法为其设置数据源。我怎样才能得到封面？如果我有字节数组，我会使用 BitmapFactory……但我没有。

顺便说一句，这是我的代码... 在活动中，这是在外部存储中搜索音频文件并将它们放入列表中的空白：

public void retrieveAudioFiles(){
        songsList = new SongsList();

        Uri sd = Audio.Media.EXTERNAL_CONTENT_URI;
        String[] cols = {Audio.Media.TITLE,Audio.Media.ARTIST,Audio.Media.ALBUM};
        String where = Audio.Media.IS_MUSIC;
        Cursor audioCursor = getContentResolver().query(sd,cols,where,null,null);

        while (audioCursor.moveToNext()){
            int posColTitle = audioCursor.getColumnIndex(Audio.Media.TITLE);
            int posColArtist = audioCursor.getColumnIndex(Audio.Media.ARTIST);
            int posColAlbum = audioCursor.getColumnIndex(Audio.Media.ALBUM);

            String songTitle = audioCursor.getString(posColTitle);
            String songArtist = audioCursor.getString(posColArtist);
            String songAlbum = audioCursor.getString(posColAlbum);

            songsList.add(new Song(songTitle,songArtist,songAlbum));
            }
        audioCursor.close();
    }

这是适配器：

public class SongsAdapter extends BaseAdapter {

    private SongsList songsList;
    private LayoutInflater songInf;

    public SongsAdapter(Context c, SongsList theSongs){
        super();  
        songsList=theSongs;
        songInf=LayoutInflater.from(c);
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return songsList.size();
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return songsList.get(position);
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        RowWrapper wrapper;
        if (convertView == null)
        {
            convertView = songInf.inflate(
                R.layout.song_row, null);
            wrapper = new RowWrapper(convertView);
            convertView.setTag(wrapper);
        }
        else
        {
            wrapper = (RowWrapper) convertView.getTag();
        }
        Song song = (Song) getItem(position);
        wrapper.populate(song);

        return convertView;
    }

    private static class RowWrapper
    {
        private TextView titleTextView;
        private TextView artistTextView;
        private TextView albumTextView;
        //private ImageView coverImageView;

        public RowWrapper(View convertView)
        {
            titleTextView = (TextView) convertView.findViewById(R.id.textTitle);
            artistTextView = (TextView) convertView.findViewById(R.id.textArtist);
            albumTextView = (TextView) convertView.findViewById(R.id.textAlbum);
            //coverImageView = (ImageView) convertView.findViewById(R.id.smallCover);
        }

        public void populate(Song song)
        {
            titleTextView.setText(song.title);
            artistTextView.setText(song.artist);
            albumTextView.setText(song.album);
            //if (song.cover != null)
            //coverImageView.setImageBitmap(song.cover);
        }
    }

}

这是 Song 类：

public class Song {

    public String title="";
    public String artist="";
    public String album="";
    public Bitmap cover=null;

    public Song(String t, String ar, String al){
        title=t;
        artist=ar;
        album=al;
        //cover=c;
    }

    public Song(){

    }

}

这是 SongsList 类（歌曲的简单 ArrayList）：

public class SongsList extends ArrayList<Song> {

    public SongsList(){
        super();
    }

}

这是清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.audioplayer"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="19" />
    <uses-permission android:name="android.permission.WAKE_LOCK"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.audioplayer.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

这是ListActivity单行的布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:orientation="vertical"
    android:onClick="songPicked" >

    <ImageView
        android:id="@+id/smallCover"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:contentDescription="@string/coverDescription"
        android:src="@drawable/no_cover" />

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

        <TextView
            android:id="@+id/labelTitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/labelTitle" />

        <TextView
            android:id="@+id/textTitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="5dp"
            android:text="@string/textTitle" />
    </LinearLayout>

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

        <TextView
            android:id="@+id/labelArtist"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="0dp"
            android:text="@string/labelArtist" />

        <TextView
            android:id="@+id/textArtist"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:paddingLeft="5dp"
            android:text="@string/textArtist" />

        <TextView
            android:id="@+id/labelAlbum"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:text="@string/labelAlbum" />

        <TextView
            android:id="@+id/textAlbum"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="5dp"
            android:text="@string/textAlbum" />
    </LinearLayout>

</LinearLayout>

希望你能帮助我...

Answer 1

我自己做的……

我在 Song 类中为 id 添加了一个长参数，为路径添加了一个 Uri 参数。

在活动中，就在songsList.add(new Song(......))之前（我在构造函数中添加了Bitmap参数），我添加了这些指令：

int posColId = audioCursor.getColumnIndex(Audio.Media._ID);
long songId = audioCursor.getLong(posColId);
Uri songUri = ContentUris.withAppendedId(Audio.Media.EXTERNAL_CONTENT_URI,songId);
String[] dataColumn = {Audio.Media.DATA};
Cursor coverCursor = getContentResolver().query(songUri, dataColumn, null, null, null);
coverCursor.moveToFirst();
int dataIndex = coverCursor.getColumnIndex(Audio.Media.DATA);
String filePath = coverCursor.getString(dataIndex);
coverCursor.close();
MediaMetadataRetriever retriever = new MediaMetadataRetriever();
retriever.setDataSource(filePath);
byte[] coverBytes = retriever.getEmbeddedPicture();
Bitmap songCover;
if (coverBytes!=null) //se l'array di byte non è vuoto, crea una bitmap
    songCover = BitmapFactory.decodeByteArray(coverBytes, 0, coverBytes.length);
else
    songCover=null;

然后我取消了 Song 类和 Adapter 中的说明。