android - 删除文件和 MediaStore-Entry

Question

我在从通过媒体存储显示的 SD 卡中删除文件时遇到了两个问题。

我有一个 ListView ，由媒体存储查询的结果填充以及底部的 4 个按钮，其中一个应该删除所选项目。

到目前为止，文件本身的删除工作正常。然而，列表永远不会更新——不是即使我重新启动程序。所以..我在下面添加了整个代码。

//new stuff is for the deleting function

import java.io.File;
import java.io.IOException;
import java.math.BigDecimal;
import android.app.ListActivity;
import android.content.Context;
import android.database.Cursor;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.provider.MediaStore;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.SeekBar;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;

public class MusicListActivity extends ListActivity {
    private static final int UPDATE_FREQUENCY = 500;
    private static final int STEP_VALUE = 10000;

    private MediaCursorAdapter mediaAdapter = null;
    private TextView selelctedFile = null;
    private SeekBar seekbar = null;
    private MediaPlayer player = null;
    private ImageButton playButton = null;
    private ImageButton prevButton = null;
    private ImageButton nextButton = null;
    private ImageButton deleteButton = null;

    private boolean isStarted = true;
    private String currentFile = "";
    private boolean isMoveingSeekBar = false;

    private final Handler handler = new Handler();

    private final Runnable updatePositionRunnable = new Runnable() {
        public void run() {
            updatePosition();
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        selelctedFile = (TextView)findViewById(R.id.selectedfile);
        seekbar = (SeekBar)findViewById(R.id.seekbar);
        playButton = (ImageButton)findViewById(R.id.play);
        prevButton = (ImageButton)findViewById(R.id.prev);
        nextButton = (ImageButton)findViewById(R.id.next);
        //new stuff
        deleteButton = (ImageButton)findViewById(R.id.delete);

        player = new MediaPlayer();

        player.setOnCompletionListener(onCompletion);
        player.setOnErrorListener(onError);
        seekbar.setOnSeekBarChangeListener(seekBarChanged);


        Cursor cursor = managedQuery( MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
             null, 
             MediaStore.Audio.Media.DATA + " like ? ",
             new String[] {"%Beruhigungssounds%"},  
             null);


        if(null != cursor)
        {
            cursor.moveToFirst();

            mediaAdapter = new MediaCursorAdapter(this, R.layout.listitem, cursor);

            setListAdapter(mediaAdapter);

            playButton.setOnClickListener(onButtonClick);
            nextButton.setOnClickListener(onButtonClick);
            prevButton.setOnClickListener(onButtonClick);
            //new stuff here
            deleteButton.setOnClickListener(onButtonClick);
        }
    }

    @Override
    protected void onListItemClick(ListView list, View view, int position, long id) {
        super.onListItemClick(list, view, position, id);

        currentFile = (String) view.getTag();

        startPlay(currentFile);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        handler.removeCallbacks(updatePositionRunnable);
        player.stop();
        player.reset();
        player.release();

        player = null;
    }

    private void startPlay(String file) {
        Log.i("Selected: ", file);

        selelctedFile.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());
        playButton.setImageResource(android.R.drawable.ic_media_pause);

        updatePosition();

        isStarted = true;
    }

    private void stopPlay() {
        player.stop();
        player.reset();
        playButton.setImageResource(android.R.drawable.ic_media_play);
        handler.removeCallbacks(updatePositionRunnable);
        seekbar.setProgress(0);

        isStarted = false;
    }

    //new stuff here
    private void delete(String file) {
        Log.i("Selected: ", file);
        selelctedFile.setText(file);
        player.stop();
        player.reset();
        playButton.setImageResource(android.R.drawable.ic_media_play);
        handler.removeCallbacks(updatePositionRunnable);
        seekbar.setProgress(0);
        isStarted = false;
        File datei = new File(file);
        datei.delete();
        selelctedFile = null;
    }
    //new stuff here

    private void updatePosition(){
        handler.removeCallbacks(updatePositionRunnable);

        seekbar.setProgress(player.getCurrentPosition());

        handler.postDelayed(updatePositionRunnable, UPDATE_FREQUENCY);
    }

    private class MediaCursorAdapter extends SimpleCursorAdapter{

        public MediaCursorAdapter(Context context, int layout, Cursor c) {
            super(context, layout, c, 
                    new String[] { MediaStore.MediaColumns.DISPLAY_NAME, MediaStore.MediaColumns.TITLE, MediaStore.Audio.AudioColumns.DURATION},
                    new int[] { R.id.displayname, R.id.title, R.id.duration });
        }

        @Override
        public void bindView(View view, Context context, Cursor cursor) {
            TextView title = (TextView)view.findViewById(R.id.title);
            TextView name = (TextView)view.findViewById(R.id.displayname);
            TextView duration = (TextView)view.findViewById(R.id.duration);

            name.setText(cursor.getString(
                    cursor.getColumnIndex(MediaStore.MediaColumns.DISPLAY_NAME)));

            title.setText(cursor.getString(
                    cursor.getColumnIndex(MediaStore.MediaColumns.TITLE)));

            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)));
        }

        @Override
        public View newView(Context context, Cursor cursor, ViewGroup parent) {
            LayoutInflater inflater = LayoutInflater.from(context);
            View v = inflater.inflate(R.layout.listitem, parent, false);

            bindView(v, context, cursor);

            return v;
        }
    }

    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(updatePositionRunnable);
                        player.pause();
                        playButton.setImageResource(android.R.drawable.ic_media_play);
                    }
                    else
                    {
                        if(isStarted)
                        {
                            player.start();
                            playButton.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.prev:
                {
                    int seekto = player.getCurrentPosition() - STEP_VALUE;

                    if(seekto < 0)
                        seekto = 0;

                    player.pause();
                    player.seekTo(seekto);
                    player.start();

                    break;
                }
                //new stuff here
                case R.id.delete:
                {
                    delete(currentFile);
                    break;
                }
                //new stuff here
            }
        }
    };

    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) {
            // returning false will call the OnCompletionListener
            return false;
        }
    };

    private SeekBar.OnSeekBarChangeListener seekBarChanged = new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            isMoveingSeekBar = false;
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {
            isMoveingSeekBar = true;
        }

        @Override
        public void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {
            if(isMoveingSeekBar)
            {
                player.seekTo(progress);

                Log.i("OnSeekBarChangeListener","onProgressChanged");
            }
        }
    };
}

Answer 1

我认为您需要更新 ContentResolver 数据库。

ContentResolver.delete(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, String where, String[] selectionArgs)

尝试:ContentResolver
此处引用:Google Groups