phone 进入睡眠状态后，我的 MediaPlayer 停止播放约 20 秒

Question

我的 MediaPlayer 在 phone 大约 20 到 30 秒后进入睡眠状态后停止播放。我失败的尝试在下面提前致谢。

    MediaPlayer mediaPlayer = new MediaPlayer();
    SeekBar seekBar;
    boolean wasPlaying = false;
    ImageButton fab;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mediaplayer);

        fab = findViewById(R.id.imageButton);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                playSong();
            }
        });

        final TextView seekBarHint = findViewById(R.id.textView);

        seekBar = findViewById(R.id.seekbar);

        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

                seekBarHint.setVisibility(View.VISIBLE);
            }

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromTouch) {
                seekBarHint.setVisibility(View.VISIBLE);
                int x = (int) Math.ceil(progress / 1000f);

                if (x < 10)
                    seekBarHint.setText("0:0" + x);
                else
                    seekBarHint.setText("0:" + x);

                double percent = progress / (double) seekBar.getMax();
                int offset = seekBar.getThumbOffset();
                int seekWidth = seekBar.getWidth();
                int val = (int) Math.round(percent * (seekWidth - 2 * offset));
                int labelWidth = seekBarHint.getWidth();
                seekBarHint.setX(offset + seekBar.getX() + val
                        - Math.round(percent * offset)
                        - Math.round(percent * labelWidth / 2));

                if (progress > 0 && mediaPlayer != null && !mediaPlayer.isPlaying()) {
                    clearMediaPlayer();
                    fab.setImageDrawable(ContextCompat.getDrawable(MediaPlayerActivity.this, android.R.drawable.ic_media_play));
                    MediaPlayerActivity.this.seekBar.setProgress(0);
                }

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {


                if (mediaPlayer != null && mediaPlayer.isPlaying()) {
                    mediaPlayer.seekTo(seekBar.getProgress());
                }
            }
        });
    }

    public void playSong() {

        try {


            if (mediaPlayer != null && mediaPlayer.isPlaying()) {
                clearMediaPlayer();
                seekBar.setProgress(0);
                wasPlaying = true;
                fab.setImageDrawable(ContextCompat.getDrawable(MediaPlayerActivity.this, android.R.drawable.ic_media_play));
            }


            if (!wasPlaying) {

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

                fab.setImageDrawable(ContextCompat.getDrawable(MediaPlayerActivity.this, android.R.drawable.ic_media_pause));

                Intent intent = getIntent();
                String user_name = intent.getStringExtra("USER_NAME");
                String file = intent.getStringExtra("FILE_NAME");

                TextView Namee = findViewById(R.id.textView3);
                Namee.setText(file);

                mediaPlayer.setDataSource(user_name);

                mediaPlayer.prepare();
                mediaPlayer.setVolume(0.5f, 0.5f);
                mediaPlayer.setLooping(false);
                seekBar.setMax(mediaPlayer.getDuration());

                mediaPlayer.start();
                new Thread(this).start();

            }

            wasPlaying = false;
        } catch (Exception e) {
            e.printStackTrace();

        }
    }

    public void run() {

        int currentPosition = mediaPlayer.getCurrentPosition();
        int total = mediaPlayer.getDuration();


        while (mediaPlayer != null && mediaPlayer.isPlaying() && currentPosition < total) {
            try {
                Thread.sleep(1000);
                currentPosition = mediaPlayer.getCurrentPosition();
            } catch (InterruptedException e) {
                return;
            } catch (Exception e) {
                return;
            }

            seekBar.setProgress(currentPosition);

        }
    }

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

    private void clearMediaPlayer() {
        mediaPlayer.stop();
        mediaPlayer.release();
        mediaPlayer = null;
    }
}

Answer 1

问题的发生是因为当你的 phone 休眠时，你的 activity 在一段时间后根据你的空闲内存和其他

销毁

重点是，对于像音乐播放这样的长时间运行任务，activity 不是一个选项。 Activity 大多数情况下，仅适用于需要用户关注、交互的任务，而不是运行在后台无限时间。

音乐播放器和如此长的运行作业需要使用服务，该服务会无限期地运行，直到用户或 OS 销毁它。

来自google doc关于服务

A Service is an application component that can perform long-running operations in the background, and it doesn't provide a user interface. Another application component can start a service, and it continues to run in the background even if the user switches to another application. Additionally, a component can bind to a service to interact with it and even perform interprocess communication (IPC). For example, a service can handle network transactions, play music, perform file I/O, or interact with a content provider, all from the background.

具体来说，对于一个音乐应用，你需要前台服务

A foreground service performs some operation that is noticeable to the user. For example, an audio app would use a foreground service to play an audio track. Foreground services must display a Notification. Foreground services continue running even when the user isn't interacting with the app.

phone 进入睡眠状态后，我的 MediaPlayer 停止播放约 20 秒

My MediaPlayer stops playing about 20 seconds after phone goes to sleep

java

android

android-mediaplayer