MediaPlayer.prepare() 给出了一个 IOException

Question

我正在从内部存储器中读取歌曲列表。我可以看到歌曲列表，但是当我单击播放它时，mp.prepare 会抛出一个 IOException。请帮忙。如果我也从内部存储读取，我是否必须添加特定权限？

public class MusicPlay extends ListActivity {
private static final String MEDIA_PATH = new String(
        "/storage/sdcard0/Music");
private List<String> songs = new ArrayList<String>();
private MediaPlayer mp = new MediaPlayer();
private int currPos = 0;
ListView lv = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    updateSongList();
}
public void updateSongList() {
    // TODO Auto-generated method stub
    File home = new File(MEDIA_PATH);
    if (home.listFiles(new Mp3Filter()).length > 0) {
        for (File file : home.listFiles(new Mp3Filter())) {
            songs.add(file.getName());
        }
    }
    ArrayAdapter<String> songList = new ArrayAdapter<String>(this,
            R.layout.song_item, songs);
    setListAdapter(songList);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    // TODO Auto-generated method stub
    super.onListItemClick(l, v, position, id);
    currPos = position;
    Toast.makeText(this, "Yes", 10).show();
    playSong(MEDIA_PATH + songs.get(position));
}
private void playSong(String songPath) {
    // TODO Auto-generated method stub
    mp.reset();
    try {
        mp.reset();
        mp.setDataSource(songPath);
        mp.prepare();
        mp.start();
        mp.setOnCompletionListener(new OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                // TODO Auto-generated method stub
                nextSong();
            }
            private void nextSong() {
                // TODO Auto-generated method stub
                if (++currPos >= songs.size()) {
                    // Last song, just reset currentPosition
                    currPos = 0;
                } else {
                    // Play next song
                    playSong(MEDIA_PATH + songs.get(currPos));
                }
            }
        });
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalStateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

Answer 1

首先，我建议不要硬编码路径，请使用这个：

if (Environment.getExternalStorageState().equals(
            Environment.MEDIA_MOUNTED)
            || Environment.getExternalStorageState().equals(
                    Environment.MEDIA_MOUNTED_READ_ONLY)) {
        File path = manager.path = Environment
                .getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC);
}

代码对我来说似乎很好，我认为你的道路是错误的。或者，您尚未向清单添加权限。

Answer 2

您缺少歌曲路径和名称之间的分隔符。将MEDIA_PATH更改为：

private static final String MEDIA_PATH = new String(
    "/storage/sdcard0/Music/");

另外，我通常建议使用 File，它在使用构造函数时会自动添加缺少的分隔符new File (String path, String name);