如何获得ListView中某个项目的ImageView的图片呢

Question

做是一个音乐播放器，每首歌曲在ListView中，其专辑图片已经读取出来了，如何实现在点击某首歌的时候将这首歌的专辑封面显示在MainActivity上。自己的思路就是读到ListView的位置，然后读取该位置的ImageView的内容返回给MainActivity的ImageView，但是不知道该如何下手，求解答。代码如下：
MainActivity：
package com.example.aw765.musicplayer;
public class MainActivity extends ListActivity {
    private static final int UPDATE_FREQUENCY=500;
    private static final int STEP_VALUE=4000;    private TextView selectedfile=null;
    private SeekBar seekBar=null;
    private MediaPlayer player=null;
    private ImageButton prev=null;
    private ImageButton play=null;
    private ImageButton next=null;
    private MediaCursorAdapter adapter=null;
    private ImageView iv_album;    private boolean isStarted=true;
    private String currentFile="";
    private boolean isMovingSeekBar=false;
    private final Handler handler=new Handler();
    private Context context;    private final Runnable updatePositinRunnable=new Runnable() {
        @Override
        public void run() {
            updatePosition();
        }
    };    private void updatePosition() {
        handler.removeCallbacks(updatePositinRunnable);
        seekBar.setProgress(player.getCurrentPosition());
        handler.postDelayed(updatePositinRunnable, UPDATE_FREQUENCY);
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        context=this;
        selectedfile=(TextView) findViewById(R.id.selecteditem);
        seekBar=(SeekBar) findViewById(R.id.seekBar);
        prev=(ImageButton) findViewById(R.id.previous);
        play=(ImageButton) findViewById(R.id.play);
        next=(ImageButton) findViewById(R.id.next);
        iv_album=(ImageView) findViewById(R.id.iv_album);        player=new MediaPlayer();
        player.setOnCompletionListener(onCompletion);
        player.setOnErrorListener(onError);
        seekBar.setOnSeekBarChangeListener(seekBarChanged);        ContentResolver resolver = context.getContentResolver();
        Cursor cursor=resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null);        if (null !=cursor){
            cursor.moveToFirst();
            adapter=new MediaCursorAdapter(this,R.layout.item,cursor);
            setListAdapter(adapter);
            prev.setOnClickListener(OnButtonClick);
            play.setOnClickListener(OnButtonClick);
            next.setOnClickListener(OnButtonClick);
        }    }    private Bitmap getAlbumArt(int album_id) {
        String mUriAlbums = "content://media/external/audio/albums";
        String[] projection = new String[]{"album_art"};
        Cursor cur = context.getContentResolver().query(Uri.parse(mUriAlbums + "/" + Integer.toString(album_id)), projection, null, null, null);
        String album_art = null;
        if (cur.getCount() > 0 && cur.getColumnCount() > 0) {
            cur.moveToNext();
            album_art = cur.getString(0);
        }
        cur.close();
        Bitmap bm = null;
        if (album_art != null) {
            bm = BitmapFactory.decodeFile(album_art);
        } else {
            bm = BitmapFactory.decodeResource(getResources(), R.drawable.default_album_art);
        }
        return bm;
    }
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        ContentResolver resolver = context.getContentResolver();
        Cursor cursor=resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null);
        /*if (cursor!=null){
            cursor.moveToFirst();
            int album_id=cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));
            iv_album.setImageBitmap(getAlbumArt(album_id));
        }*/
        /*Bitmap bm = null;
        if (album_art != null) {
            bm = BitmapFactory.decodeFile(album_art);
        } else {
            bm = BitmapFactory.decodeResource(getResources(), R.drawable.default_album_art);
        }*/
        //iv_album.setImageDrawable(album_art);
        adapter=new MediaCursorAdapter(this,R.layout.item,cursor);        currentFile = (String) v.getTag();
        startPlay(currentFile);
    }
    private void startPlay(String file) {
        Log.i("Selected: ", file);
        selectedfile.setText(file);
        seekBar.setProgress(0);
        player.stop();
        player.reset();        try {
            player.setDataSource(file);
            player.prepare();
            player.start();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        seekBar.setMax(player.getDuration());
        play.setImageResource(android.R.drawable.ic_media_pause);
        updatePosition();
        isStarted = true;
    }    private void stopPlay() {
        player.stop();
        player.reset();
        play.setImageResource(android.R.drawable.ic_media_play);
        handler.removeCallbacks(updatePositinRunnable);
        seekBar.setProgress(0);
        isStarted = false;
    }    @Override
    protected void onDestroy() {
        super.onDestroy();
        handler.removeCallbacks(updatePositinRunnable);
        player.stop();
        player.reset();
        player.release();
        player = null;
    }    private View.OnClickListener OnButtonClick = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.play: {
                    if (player.isPlaying()) {
                        handler.removeCallbacks(updatePositinRunnable);
                        player.pause();
                        play.setImageResource(android.R.drawable.ic_media_play);
                    } else {
                        if (isStarted) {
                            player.start();
                            play.setImageResource(android.R.drawable.ic_media_pause);
                            updatePosition();
                        } else {
                            startPlay(currentFile);
                        }
                    }
                    break;
                }                case R.id.next: {
                    int seekto = player.getCurrentPosition() + STEP_VALUE;
                    if (seekto > player.getDuration())
                        seekto = player.getDuration();
                    player.pause();
                    player.seekTo(seekto);
                    player.start();
                    break;
                }                case R.id.previous: {
                    int seekto = player.getCurrentPosition() - STEP_VALUE;
                    if (seekto < 0)
                        seekto = 0;
                    player.pause();
                    player.seekTo(seekto);
                    player.start();
                    break;
                }
            }
        }
    };
    private MediaPlayer.OnCompletionListener onCompletion = new MediaPlayer.OnCompletionListener() {
        @Override
        public void onCompletion(MediaPlayer mp) {
            stopPlay();
        }        ;
    };
    private MediaPlayer.OnErrorListener onError = new MediaPlayer.OnErrorListener() {
        @Override
        public boolean onError(MediaPlayer mp, int what, int extra) {
            return false;
        }
    };    private SeekBar.OnSeekBarChangeListener seekBarChanged =
            new SeekBar.OnSeekBarChangeListener() {
                @Override
                public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                    if (isMovingSeekBar) {
                        player.seekTo(progress);
                        Log.i("OnSeekBarChangeListener", "OnProgressChanged");
                    }
                }                @Override
                public void onStartTrackingTouch(SeekBar seekBar) {
                    isMovingSeekBar = true;
                }                @Override
                public void onStopTrackingTouch(SeekBar seekBar) {
                    isMovingSeekBar = false;
                }
            };
}
Adapter主要部分代码：        album.setText(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM)));
        title.setText(cursor.getString(cursor.getColumnIndex(MediaStore.MediaColumns.TITLE)));
        int album_id=cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));
        long durationInMS=Long.parseLong(cursor.getString(cursor.getColumnIndex(MediaStore.Audio.AudioColumns.DURATION)));
        double durationInMin=((double)durationInMS/1000.0)/60.0;
        durationInMin=new BigDecimal(Double.toString(durationInMin)).setScale(2,BigDecimal.ROUND_UP).doubleValue();
        duration.setText(""+durationInMin);
        view.setTag(cursor.getString(cursor.getColumnIndex(MediaStore.MediaColumns.DATA)));        String mUriAlbums = "content://media/external/audio/albums";
        String[] projection = new String[] { "album_art" };
        Cursor cur = resolver.query(Uri.parse(mUriAlbums + "/" + Integer.toString(album_id)), projection, null, null, null);
        String album_art = null;
        if (cur.getCount() > 0 && cur.getColumnCount() > 0){
            cur.moveToNext();
            album_art = cur.getString(0);
        }
        cur.close();
        cur = null;        Bitmap bitmap=null;
        if (album_art==null){
            iv_album_small.setBackgroundResource(R.drawable.default_album_art);
        }else {
            bitmap=BitmapFactory.decodeFile(album_art);
            BitmapDrawable bitmapDrawable=new BitmapDrawable(bitmap);
            ((ImageView) iv_album_small).setImageDrawable(bitmapDrawable);        }
    }
求解答！！！

Answer 1

定义一个List<String> imgFilePaths;
 ContentResolver resolver = context.getContentResolver();
        Cursor cursor=resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null);
 
 
 
        if (null !=cursor){
            cursor.moveToFirst();
            
            setListAdapter(adapter);
            prev.setOnClickListener(OnButtonClick);
            play.setOnClickListener(OnButtonClick);
            next.setOnClickListener(OnButtonClick);
        }

Answer 2

定义一个List<String> imgFilePaths;adapter=new MediaCursorAdapter(this,R.layout.item,imgFilePaths);
            setListAdapter(adapter);       
    
开启子线程查询获取数据
 ContentResolver resolver = context.getContentResolver();
        Cursor cursor=resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null);        if (null !=cursor){
            cursor.moveToFirst();
            
           prev.setOnClickListener(OnButtonClick);
            play.setOnClickListener(OnButtonClick);
            next.setOnClickListener(OnButtonClick);
           ...   //在这里获取所有封面图片途径
           ...
          然后Handler发消息  接收消息后adapter.notifyDatasetChanged()
        }
ListView的item点击事件中
 String imgPath=imgFilePaths.get(position);
然后就是Activity间传数据或者回传数据了

Answer 3

可是MediaCursorAdapter里第三个参数要求的是Cursor类的诶...

Answer 4

楼上只是举个例子，意思是让你代码获取图片路径。
现在你需要得到音乐路径或直接得到图片路径就行了
如何得到路径：在你的MediaCursorAdapter里面找到查询逻辑把路径保存下来即可

Answer 5

主要是获取不到额。。因为在MediaCursorAdapter里获取了很多专辑图，具体要哪一张需要点击获取位置后再根据位置传回路径嘛，我回头改成BaseAdapter用getView方法来写一下吧。

Answer 6

对的，根据MediaCursorAdapter获取专辑图的逻辑用arrayList保存（MediaCursorAdapter应该保存过了，其实你应该只需要把私有list改成protected的就行了），然后onItemClick时用list.get(position)来获取

Answer 7

这个可以用控件下载，很多控件其实比自己开发用起来还更加方便快捷。推荐去 https://blog.csdn.net/john_dwh 这个博客找找你的需求看看有没有为你解答。