Android：使用MediaPlayer和SurfaceView播放视频

android

Android中提供的MediaPlayer播放器并没有提供视频输出界面，所以我们需要使用SurfaceView来当做图像的输出界面。
使用步骤如下：

• 创建MediaPlayer对象，并加载视频文件
• 为SurfaceView的SurfaceHolder添加监听器CallBack
• 调用MediaPlayer对象的setDisplay(SurfaceHolder hd)将播放的视频图像输出到指定的SurfaceView(注意，此方法需要在SurfaceView被完全创建后调用，不然会抛出The surface has been released异常)

下列程序示例，这里千万注意setDisplay方法一定要在监听回调中调用，否则会由于SurfaceView并未完全创建而引发异常

class SMActivity : BaseActivity<IPresenter>() {
    init {
        orientation = Orientation.LANDSCAPE
    }
    val mp = MediaPlayer()
    var isScroll = false
    val loop = ThreadUtils.Loop(500).loop {
        if (!isScroll)
            smSeekBar.progress = mp.currentPosition
    }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_sm)
        smStart.setOnClickListener { start() }
        smPause.setOnClickListener { pause() }
        smStop.setOnClickListener { stop() }
        mp.setAudioStreamType(AudioManager.STREAM_MUSIC)
        mp.setDataSource(video)
        mp.prepare()
        smSeekBar.max = mp.duration
        smSeekBar.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener {
            override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
            }
            override fun onStartTrackingTouch(seekBar: SeekBar?) {
                isScroll = true
            }
            override fun onStopTrackingTouch(seekBar: SeekBar) {
                mp.seekTo(seekBar.progress)
                isScroll = false
            }
        })
        smSurfaceView.holder.setKeepScreenOn(true)
        smSurfaceView.holder.addCallback(object : SurfaceHolder.Callback {
            override fun surfaceChanged(holder: SurfaceHolder?, format: Int, width: Int, height: Int) {
            }
            override fun surfaceDestroyed(holder: SurfaceHolder?) {
            }
            override fun surfaceCreated(holder: SurfaceHolder) {
                //********************************************
                mp.setDisplay(holder)//*******注意************
                //********************************************
            }
        })
    }
    fun start() {
        if (!mp.isPlaying) {
            mp.start()
            loop.start()
        }
    }
    fun pause() {
        if (mp.isPlaying) {
            mp.pause()
        }
    }
    fun stop() {
        mp.stop()
        loop.destroy()
    }
    override fun onDestroy() {
        if (mp.isPlaying) stop()
        mp.release()
        super.onDestroy()
    }
}