android - 媒体播放器在后台

Question

这是我拥有的创建音频播放器并允许我的应用程序用户听音乐的代码。当手机进入休眠状态时，如何让音频在后台运行？我想尽可能对下面的代码进行最小的更改。那可能吗？

class AudioActivity : BaseActivity() {

    private lateinit var mediaPlayer: MediaPlayer
    private lateinit var runnable: Runnable
    private var handler: Handler = Handler()
    private var pause: Boolean = false
    private var working: Boolean = false
    private var removeFromLibrary: Boolean = false;


    private fun stop () {
        try {
            if ((mediaPlayer.isPlaying || pause.equals(true))) {
                pause = false
                seek_bar.setProgress(0)
                mediaPlayer.stop()
                mediaPlayer.reset()
                mediaPlayer.release()
                handler.removeCallbacks(runnable)

                tv_pass.text = ""
                tv_due.text = ""
            }
        } catch(e: UninitializedPropertyAccessException) {
            // media player is not initialized
        }
    }

    override fun onStop() {
        super.onStop()

        stop()
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_audio)

        setProgressBar(R.id.progressBar)


        // Start the media player
        playBtn.setOnClickListener {
            if (!working) {
                working = true

                if (pause && mediaPlayer.isPlaying) {
                    playBtn.setImageResource(R.drawable.ic_play_circle_filled);
                    mediaPlayer.pause()
                } else {
                    playBtn.setImageResource(R.drawable.pausebtn);

                    if (pause) {
                        mediaPlayer.seekTo(mediaPlayer.currentPosition)
                        mediaPlayer.start()
                    } else {
                        mediaPlayer = MediaPlayer.create(applicationContext, Uri.parse(intent.getStringExtra("audio")))
                        mediaPlayer.start()
                    }
                    initializeSeekBar()

                    mediaPlayer.setOnCompletionListener {
                        Toast.makeText(this, "end", Toast.LENGTH_SHORT).show()
                    }
                }

                pause = !pause;
                working = false
            }
        }

        prevBtn.setOnClickListener {
            if (!working) {
                working = true
                try {
                    mediaPlayer.seekTo(mediaPlayer.currentPosition + (-10*1000))

                } catch(e: UninitializedPropertyAccessException) {
                    // media player is not initialized
                }
                working = false
            }
        }


        nextBtn.setOnClickListener {
            if (!working) {
                working = true
                try {
                    mediaPlayer.seekTo(mediaPlayer.currentPosition + (10*1000))
                } catch(e: UninitializedPropertyAccessException) {
                    // media player is not initialized
                }
                working = false
            }

        }

        // Seek bar change listener
        seek_bar.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener {
            override fun onProgressChanged(seekBar: SeekBar, i: Int, b: Boolean) {
                if (b) {
                    try {
                        mediaPlayer.seekTo(i * 1000)
                    } catch(e: UninitializedPropertyAccessException) {
                        // media player is not initialized
                    }
                }
            }

            override fun onStartTrackingTouch(seekBar: SeekBar) {
            }

            override fun onStopTrackingTouch(seekBar: SeekBar) {
            }
        })
    }

    // Method to initialize seek bar and audio stats
    private fun initializeSeekBar() {
        seek_bar.max = mediaPlayer.seconds

        runnable = Runnable {
            seek_bar.progress = mediaPlayer.currentSeconds

            var minutesaddum = "";
            var secondsaddum = ""
            val minutes = mediaPlayer.currentSeconds  / 60
            val seconds = mediaPlayer.currentSeconds  % 60

            if (minutes < 10) {
                minutesaddum = "0"
            }
            if (seconds < 10) {
                secondsaddum = "0"
            }
            tv_pass.text = "${minutesaddum}${minutes}:${secondsaddum}${seconds}"
            val diff = mediaPlayer.seconds - mediaPlayer.currentSeconds


            var minutesdiffaddum = "";
            var secondsdiffaddum = ""
            val minutesdiff = diff  / 60
            val secondsdiff = diff  % 60


            if (minutesdiff < 10) {
                minutesdiffaddum = "0"
            }
            if (secondsdiff < 10) {
                secondsdiffaddum = "0"
            }

            tv_due.text = "${minutesdiffaddum}${minutesdiff}:${secondsdiffaddum}${secondsdiff}"

            handler.postDelayed(runnable, 1000)
        }
        handler.postDelayed(runnable, 1000)
    }

// Creating an extension property to get the media player time duration in seconds
val MediaPlayer.seconds: Int
    get() {
        return this.duration / 1000
    }

// Creating an extension property to get media player current position in seconds
val MediaPlayer.currentSeconds: Int
    get() {
        return this.currentPosition / 1000
    }

Answer 1

如果您需要创建一个在后台播放的媒体播放器。我建议你先创建一个服务。即使您杀死应用程序，此服务也会让媒体播放器一直播放。

记住也要创建通知。此通知将保持服务作为代码运行: startForeground(0, notification);

来自 Android 的示例:https://developer.android.com/guide/components/services

希望这有帮助!