我为这个noobish问题道歉，但是我正在android studio中构建一个音乐播放器，我在播放这些歌曲时遇到了问题，就像播放列表一样。歌曲只能用手挑选，歌曲结束后才会停止，直到用户点击另一首歌曲为止。我写了两段代码，我怀疑它会解决这个问题，但我不确定如何实现它们，或者它们最终是否会有任何用处。我真的很感激一些帮助，真的可以使用它。任何建议或建设性的批评总是受到欢迎，提前谢谢。这里是片段：
//------------> to get the next song <---------------
int itemsInList=list.getAdapter().getCount();
for(int i=1;i<itemsInList;i++){
list.setSelection(i);
}
//--------------> to play the song on list item click <-------------------
@Override
protected void onListItemClick(ListView list, View view, int position,
long id) {
super.onListItemClick(list, view, position, id);
currentFile = (String) view.getTag();
startPlay(currentFile);
}
这里仅供参考，是我的主要java文件：
public class MainActivity extends ListActivity {
private static final int UPDATE_FREQUENCY = 500;
private static final int STEP_VALUE = 4000;
private MediaCursorAdapter mediaAdapter = null;
private TextView selectedFile = null;
private SeekBar seekbar = null;
private MediaPlayer player = null;
private ListView list = null;
private ImageButton playButton = null;
private ImageButton prevButton = null;
private ImageButton nextButton = null;
private ImageButton btNext = null;
private ImageButton btPrev = null;
private boolean isStarted = true;
private String currentFile = "";
private boolean isMovingSeekBar = false;
private final Handler handler = new Handler();
private final Runnable updatePositionRunnable = new Runnable() {
public void run() {
updatePosition();
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
selectedFile = (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);
btNext = (ImageButton) findViewById(R.id.btNxt);
btPrev = (ImageButton) findViewById(R.id.btPrev);
player = new MediaPlayer();
player.setOnCompletionListener(onCompletion);
player.setOnErrorListener(onError);
seekbar.setOnSeekBarChangeListener(seekBarChanged);
Cursor cursor = getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null, null);
if (null != cursor) {
cursor.moveToFirst();
mediaAdapter = new MediaCursorAdapter(this, R.layout.list_item, cursor);
setListAdapter(mediaAdapter);
playButton.setOnClickListener(onButtonClick);
nextButton.setOnClickListener(onButtonClick);
prevButton.setOnClickListener(onButtonClick);
btNext.setOnClickListener(onButtonClick);
btPrev.setOnClickListener(onButtonClick);
}
}
//----------- ??? ----------------------------------------------------------------
int itemsInList=list.getAdapter().getCount();
for(int i=1;i<itemsInList;i++){
list.setSelection(i);
}
@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);
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());
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;
}
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.list_item, 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;
}
case R.id.btNxt: {
//TO DO
}
case R.id.btPrev: {
//TO DO
}
}
}
};
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 onStopTrackingTouch(SeekBar seekBar) {
isMovingSeekBar = false;
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
isMovingSeekBar = true;
}
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
if (isMovingSeekBar) {
player.seekTo(progress);
Log.i("OnSeekBarChangeListener", "onProgressChanged");
}
}
};
}
答案 0 :(得分：4)
您可以查看下面的方法播放下一首歌曲。希望它有所帮助。
$this->registerJs('
$.pjax.defaults.timeout = 5000;
$("#product-form-pjax").on("pjax:end", function(data, status, xhr, options) {
if(options.responseText == "Success"){
$.pjax.reload({container: "#pjax-gridview", timeout: 2000});
$("#activity-modal").modal("hide");
}
});
', $this::POS_READY);
这是播放歌曲的playBackMusic（）方法：
public static void nextSong() {
int numOfSong = songList.size();
if (!isShuffle) { // Shuffle mode is off
if (currentPosition < numOfSong - 1) {
currentPosition++;
currentSong = songList.get(currentPosition);
Log.d("my_log", "position = "+currentPosition);
playBackMusic();
} else {
currentPosition = 0;
currentSong = songList.get(currentPosition);
Log.d("my_log", "position = "+currentPosition);
playBackMusic();
}
} else { // Shuffle mode is on
Random rand = new Random();
currentPosition = rand.nextInt(numOfSong);
currentSong = songList.get(currentPosition);
Log.d("my_log", "position = "+currentPosition);
playBackMusic();
}
}
方法endOfTheSong（）处理播放当前歌曲后的操作。
public static void playBackMusic() {
try {
mediaPlayer.release();
mediaPlayer = new MediaPlayer();
mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
mediaPlayer.setDataSource(currentSong.getPath());
mediaPlayer.prepare();
mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
endOfTheSong();
}
});
isPlaying = true;
mediaPlayer.start();
} catch (Exception e) {
e.printStackTrace();
}
}