android - ListView 中与 MediaPlayer 关联的多个 SeekBar

Question

我有一个显示语音消息的 ListView(就像 WhatsApp 的一样)，我正在使用 BaseAdapter，我的布局包含一个播放 按钮 和一个 SeekBar。我想要的是在点击播放 按钮 时播放音频，并更新 SeekBar。

所以我实现了这个自更新的自定义 SeekBar。

SelfUpdatingSeekBar.java:

public class SelfUpdatingSeekBar extends SeekBar {

MediaPlayer mp;
boolean mActive;


public void setMediaPlayer(MediaPlayer mp){
    this.mp = mp;
}


Runnable mUpdate = new Runnable() {
    @Override
    public void run() {
        long totalDuration = mp.getDuration();
        long currentDuration = mp.getCurrentPosition();

        // Updating progress bar
        int progress = (int)(getProgressPercentage(currentDuration, totalDuration));
        setProgress(progress);
        postDelayed(this, 100);
    }
} ;

public void setActive(int progress) {
    if (!mActive) {
        mActive = true;
        removeCallbacks(mUpdate);
        setProgress(progress);
        post(mUpdate);
    }
}

public void setInactive(int progress) {
    if (mActive) {
        mActive = false;
        removeCallbacks(mUpdate);
    }
    setProgress(progress);
}



public SelfUpdatingSeekBar(Context context) {
    super(context);
}

public SelfUpdatingSeekBar(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public SelfUpdatingSeekBar(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
}

public SelfUpdatingSeekBar(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    super(context, attrs, defStyleAttr, defStyleRes);
}



public int getProgressPercentage(long currentDuration, long totalDuration){
    Double percentage = (double) 0;

    long currentSeconds = (int) (currentDuration / 1000);
    long totalSeconds = (int) (totalDuration / 1000);

    // calculating percentage
    percentage =(((double)currentSeconds)/totalSeconds)*100;

    // return percentage
    return percentage.intValue();
}

}

这就是我的 getView() 的样子:

public View getView(final int i, View convertView, ViewGroup viewGroup){

    final ViewHolder viewHolder;



    if(convertView == null){
        LayoutInflater inflater = ((MainActivity) context).getLayoutInflater();
        viewHolder = new ViewHolder();
        convertView = inflater.inflate(R.layout.sent_voice_bubble, viewGroup, false);

        viewHolder.sent_voice_seekbar = (SelfUpdatingSeekBar) convertView.findViewById(R.id.sent_seekbar);
        viewHolder.sent_voice_seekbar.setMediaPlayer(mMediaPlayer);
        viewHolder.sent_voice_play = (ImageView) convertView.findViewById(R.id.sent_playAudio);
        viewHolder.sent_voice_container = convertView.findViewById(R.id.sent_vmessagesection);
        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(((int)(x * 0.7f)), RelativeLayout.LayoutParams.WRAP_CONTENT);
        params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
        viewHolder.sent_voice_container.setLayoutParams(params);

        convertView.setTag(viewHolder);
    }else{
        viewHolder = (ViewHolder) convertView.getTag();
    }


            viewHolder.sent_voice_play.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                // Check if the Item is currently playing 
                    if(list.get(i).isPlaying()){
                        // Stop audio and save  progress
                        stopItemAudio(list.get(i), viewHolder.sent_voice_seekbar);
                        // Change button's image to Pause ||
                        ((ImageView) v).setImageDrawable(((MainActivity) context).pauseDrawable);

                    }else{
                        // Start audio and update the SeekBar
                        playItemAudio(list.get(i), viewHolder.sent_voice_seekbar);
                        // Change button's image to Play >
                        ((ImageView) v).setImageDrawable(((MainActivity) context).playDrawable);
                    }
                }
            });

            if(list.get(i).isPlaying()){
                viewHolder.sent_voice_seekbar.setActive(list.get(i).seekbar_resume_position);
                viewHolder.sent_voice_play.setImageDrawable(((MainActivity) context).pauseDrawable);
            }else{
                viewHolder.sent_voice_seekbar.setInactive(list.get(i).seekbar_resume_position);
                viewHolder.sent_voice_play.setImageDrawable(((MainActivity) context).playDrawable);
            }


    return convertView;
}




public void stopItemAudio(AudioRow item, SelfUpdatingSeekBar seekBar){

    if(mMediaPlayer == null){
        mMediaPlayer = new MediaPlayer();
    }

    mMediaPlayer.stop();
    item.setPlaying(false);
    int percentage = getProgressPercentage(mMediaPlayer.getCurrentPosition(), mMediaPlayer.getDuration());

    item.setSeekBarResumePosition(percentage);
    item.setMediaPlayerResumePosition(mMediaPlayer.getCurrentPosition());
    seekBar.setInactive(percentage);
    notifyDataSetChanged();

}
public void playItemAudio(final AudioRow item, SelfUpdatingSeekBar seekBar){
    if(mMediaPlayer == null){
        mMediaPlayer = new MediaPlayer();
    }

    try {
        mMediaPlayer.reset();
        mMediaPlayer.setDataSource(item.audioPath);
        mMediaPlayer.prepare();
        mMediaPlayer.seekTo(item.mediaPlayer_resume_position);
        seekBar.setActive(item.seekbar_resume_position); // Starts from where it stopped
        mMediaPlayer.start();

        // declaring Item started to play
        item.setPlaying(true);
        notifyDataSetChanged();

        mMediaPlayer.setOnCompletionListener(new OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                item.setSeekBarResumePosition(0);
                item.setPlaying(false);
            }
        });
    } 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();
    }



public int getProgressPercentage(long currentDuration, long totalDuration){
    Double percentage = (double) 0;

    long currentSeconds = (int) (currentDuration / 1000);
    long totalSeconds = (int) (totalDuration / 1000);

    // calculating percentage
    percentage =(((double)currentSeconds)/totalSeconds)*100;

    // return percentage
    return percentage.intValue();
}

}

问题是当我点击 Item1 时，它开始播放，然后点击 Item2 两个 SeekBars 同时动画，这是预期的，因为我做了单击 Item2

时不会停止 Item1

我的问题是:

• 在单击 Item2 时停止上一个播放的 Item1 的正确方法是什么？

Answer 1

您的 SeekBar 实现不应有自己的 MediaPlayer。在您的 Activity 中只有一个 MediaPlayer 实例。每次在 ListView 中单击“播放”按钮时，您都会执行以下操作:

MediaPlayer mMediaPlayer = ((MainActivity) context).getSingleMediaPlayer();
((MainActivity) context).setCurrentlyPlayingItem(i);
mMediaPlayer.reset();
mMediaPlayer.setDataSource(item.audioPath);
mMediaPlayer.prepare();
notifyDatasetHasChanged()

现在在您的 getView() 实现上，如果第一个参数:i 不等于 MainActivity 的当前播放项目 SeekBar 应该为零。

MainActivity 也应该是实现可运行更新的那个。此时您可能只想使用普通的 SeekBar。要更新正确的 View ，您需要先确定它是否可见，因为用户可能已经滚动到不同的位置，所以您需要在 MainActivity 中使用此功能:

public View getVisibleItemView(int position){
        if(listview.getCount() > 0) {
            int start = listview.getFirstVisiblePosition();
            for (int i = start, j = listview.getLastVisiblePosition(); i <= j; i++) {
                if (i == position) {
                    return listview.getChildAt(i - start);
                }
            }
        }
        return null;
    }

此函数返回包含要更新的 SeekBar 的 View ，但前提是它可见，否则返回 null。在你的 update runnable 中你应该调用它，如果结果不为空，你更新 SeekBar。

此外，您可能需要考虑使用接口(interface)而不是将上下文引用强制转换为适配器中的 MainActivity。