基本上，我得到了一个显示乐队列表的列表视图。 当我按下列表中的一个频段时，它会通过适配器创建一个频段配置文件页面。 在这个布局中，我有一个播放按钮，它启动 MediaPlayer 服务并播放歌曲。
到目前为止，一切都很好。
问题是，我尝试从 MediaPlayer 服务 Java 文件更新位于乐队配置文件页面（由上述适配器创建）中的eekBar，但我无法访问它。
我正在尝试使用：
LayoutInflater inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
View layout = inflater.inflate(R.layout.activity_singleband, null, false);
seekBar = (SeekBar) layout.findViewById(R.id.seekBarBand);
但它似乎使用了视图的另一个“实例”，而不是我当前正在查看的那个。
这是完整的 MusicService Java 文件：
public class MusicService extends Service {
SeekBar seekBar;
Handler handler;
Runnable runnable;
NotificationManager nMN;
TextView BandName;
String songLink;
String songName;
String bandName;
String SongPlaying="";
String BandPlaying="";
public static MediaPlayer mp;
public static Boolean mpState = true;
public static Boolean mpPause = false;
public static Boolean isPlaying = false;
@Override
public void onCreate() {
super.onCreate();
}
// Play Cycle for seekBar
public void PlayCycle(){
seekBar.setProgress(mp.getCurrentPosition());
if (mp.isPlaying()){
runnable = new Runnable() {
@Override
public void run() {
PlayCycle();
}
};
handler.postDelayed(runnable, 1000);
}
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
songLink = intent.getStringExtra("SongLink");
songName = intent.getStringExtra("SongName");
bandName = intent.getStringExtra("BandName");
LayoutInflater inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
View layout = inflater.inflate(R.layout.activity_singleband, null, false);
seekBar = (SeekBar) layout.findViewById(R.id.seekBarBand);
BandName = (TextView) layout.findViewById(R.id.singleBandNameView);
BandName.setText("Bla Bla");
System.out.print("Band Name : "+ BandName.getText() );
handler = new Handler();
seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean input) {
if (input){
mp.seekTo(progress);
}
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
if (isPlaying && !songName.equals(SongPlaying) && !BandPlaying.equals(bandName)) {
Stop();
mp = new MediaPlayer();
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
Uri songUri = Uri.parse(songLink);
mp.setDataSource(getApplicationContext(), songUri);
SongPlaying = songName;
Toast.makeText(getApplicationContext(), "Please wait", Toast.LENGTH_SHORT).show();
isPlaying=true;
new prepare().execute();
}
catch (IOException e) {
e.printStackTrace();
}
}
else if (!isPlaying && !songName.equals(SongPlaying) && !BandPlaying.equals(bandName) ) {
mp = new MediaPlayer();
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
Uri songUri = Uri.parse(songLink);
mp.setDataSource(getApplicationContext(), songUri);
SongPlaying = songName;
Toast.makeText(getApplicationContext(), "Please wait", Toast.LENGTH_SHORT).show();
new prepare().execute();
isPlaying=true;
}
catch (IOException e) {
e.printStackTrace();
}
}
else {
Toast.makeText(getApplicationContext(), "Song is Already Playing", Toast.LENGTH_SHORT).show();
}
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
super.onDestroy();
mp.release();
handler.removeCallbacks(runnable);
}
/// Permanent Notification
private void showNotification() {
nMN = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
Notification n = new Notification.Builder(this)
.setContentTitle(songName)
.setContentText(bandName)
.setSmallIcon(R.drawable.ic_bandcamp)
//.addAction(R.drawable.ic_play_arrow_black_24dp, "button1", new pause())
.setOngoing(true)
.build();
nMN.notify(1, n);
}
/// PREPARE SONG TO PLAY //
public class prepare extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.prepare();
PlayCycle();
seekBar.setMax(mp.getDuration());
mp.start();
SongPlaying = songName;
isPlaying=true;
showNotification(); // show notification
mp.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
Toast.makeText(getApplicationContext(),"Song Finished", Toast.LENGTH_LONG).show();
new stop().execute();
}
});
} catch (IOException io){ io.printStackTrace(); }
return null; }}
/// STOP PLAYING SONG //
public static void Stop()
{
mp.reset();
mp.release();
isPlaying=false;
}
public static class stop extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.reset();
mp.release();
isPlaying=false;
} catch (Exception io){ io.printStackTrace(); }
return null; }}
/// PAUSE PLAYING SONG//
public static class pause extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.pause(); }
catch (Exception io){ io.printStackTrace(); }
return null; }}
public static class start extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.start(); }
catch (Exception io){ io.printStackTrace(); }
return null; }}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
}
好吧，首先我建议您阅读有关 Android Service 类的更多信息。其次，不要将可视化组件（如 SeekBar 或 TextView）放置在服务中，因为它没有任何意义。服务只是一个后台任务，不了解 UI。由于它是在后台执行的，因此您甚至不需要其中的 AsyncTask，因此第三次删除服务中的ALL AsyncTasks 并运行它们的任务，就像它们不需要在后台执行一样。 因此，您所要做的就是为 UI 创建一个 Fragment/Activity，然后将您的 Fragment/Activity 与您的 Service 绑定以进行通信和更新 UI 组件。 最简单的方法是使服务成为单例，就像这里所做的那样：
public class MusicService extends Service {
private static MusicService instance = null;
public static MusicService getInstance() {
return instance;
}
Handler handler;
Runnable runnable;
NotificationManager nMN;
String songLink;
String songName;
String bandName;
String SongPlaying="";
String BandPlaying="";
public static MediaPlayer mp;
public static Boolean mpState = true;
public static Boolean mpPause = false;
public static Boolean isPlaying = false;
@Override
public void onCreate() {
instance = this;
super.onCreate();
}
// Play Cycle for seekBar
public void PlayCycle(){
seekBar.setProgress(mp.getCurrentPosition());
if (mp.isPlaying()){
runnable = new Runnable() {
@Override
public void run() {
PlayCycle();
}
};
handler.postDelayed(runnable, 1000);
}
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
songLink = intent.getStringExtra("SongLink");
songName = intent.getStringExtra("SongName");
bandName = intent.getStringExtra("BandName");
handler = new Handler();
if (isPlaying && !songName.equals(SongPlaying) && !BandPlaying.equals(bandName)) {
Stop();
mp = new MediaPlayer();
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
Uri songUri = Uri.parse(songLink);
mp.setDataSource(getApplicationContext(), songUri);
SongPlaying = songName;
Toast.makeText(getApplicationContext(), "Please wait", Toast.LENGTH_SHORT).show();
isPlaying=true;
new prepare().execute();
}
catch (IOException e) {
e.printStackTrace();
}
}
else if (!isPlaying && !songName.equals(SongPlaying) && !BandPlaying.equals(bandName) ) {
mp = new MediaPlayer();
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
Uri songUri = Uri.parse(songLink);
mp.setDataSource(getApplicationContext(), songUri);
SongPlaying = songName;
Toast.makeText(getApplicationContext(), "Please wait", Toast.LENGTH_SHORT).show();
new prepare().execute();
isPlaying=true;
}
catch (IOException e) {
e.printStackTrace();
}
}
else {
Toast.makeText(getApplicationContext(), "Song is Already Playing", Toast.LENGTH_SHORT).show();
}
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
super.onDestroy();
mp.release();
handler.removeCallbacks(runnable);
}
/// Permanent Notification
private void showNotification() {
nMN = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
Notification n = new Notification.Builder(this)
.setContentTitle(songName)
.setContentText(bandName)
.setSmallIcon(R.drawable.ic_bandcamp)
//.addAction(R.drawable.ic_play_arrow_black_24dp, "button1", new pause())
.setOngoing(true)
.build();
nMN.notify(1, n);
}
/// PREPARE SONG TO PLAY //
public class prepare extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.prepare();
PlayCycle();
seekBar.setMax(mp.getDuration());
mp.start();
SongPlaying = songName;
isPlaying=true;
showNotification(); // show notification
mp.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
Toast.makeText(getApplicationContext(),"Song Finished", Toast.LENGTH_LONG).show();
new stop().execute();
}
});
} catch (IOException io){ io.printStackTrace(); }
return null; }}
/// STOP PLAYING SONG //
public static void Stop()
{
mp.reset();
mp.release();
isPlaying=false;
}
public static class stop extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.reset();
mp.release();
isPlaying=false;
} catch (Exception io){ io.printStackTrace(); }
return null; }}
/// PAUSE PLAYING SONG//
public static class pause extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.pause(); }
catch (Exception io){ io.printStackTrace(); }
return null; }}
public static class start extends AsyncTask {
@Override
protected Object doInBackground(Object[] objects) {
try {
mp.start(); }
catch (Exception io){ io.printStackTrace(); }
return null; }}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
// throw new UnsupportedOperationException("Not yet implemented");
return null;
}