随着快手，抖音，西瓜视频等视频APP的崛起，视频播放已经成为主流，此时做为Android研发的你，想要提升本身的能力还不知道怎么开发视频播放器怎么行？
视频播放器有原生的VideoView、开源的Ijkplayer?、ExoPlayer、JieCaoVideoPlayer等等，这些部分的播放器我们在开发过程中，使用过这些视频播放框架来播放本地视频或者网络视频，但不一定会满足业务需求的。因此，我们可以去自定义一个播放器，在开发Android应用的过程中，难免需要自定义View，其实自定义View不难，只要了解原理，实现起来就没有那么难，从而满足业务需求。
先看效果图。

player.gif

我自定义一个VideoPlayerView类，主要是由MediaPlayer与SurfaceView相结合组成一个视频播放器，从Android原生的VideoView视频框架，也是基于实现的。

1.png

2.png

1.首先编写布局文件layout_video_player.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
   <RelativeLayout
       android:layout_width="match_parent"
       android:layout_height="250dp"
       android:orientation="vertical"
       >
       <SurfaceView
           android:id="@+id/surfaceview"
           android:layout_width="match_parent"
           android:layout_height="match_parent"/>
       <LinearLayout
           android:layout_width="match_parent"
           android:layout_height="50dp"
           android:orientation="horizontal"
           android:layout_alignParentBottom="true"
           >
           <TextView
               android:id="@+id/tvCurrentTime"
               android:layout_width="0dp"
               android:layout_height="match_parent"
               android:layout_weight="0.1"
               android:gravity="center|right"
               android:text="00:00"
               android:textSize="12dp"
               android:textColor="#FFFFFFFF"
               />
           <SeekBar
               android:id="@+id/seekBar"
               android:layout_width="0dp"
               android:layout_height="10dp"
               android:layout_weight="0.9"
               android:progressDrawable="@drawable/seekbar_progress_drawable"
               android:maxHeight="2dp"
               android:minHeight="1dp"
               android:thumb="@drawable/round_bg"
               android:layout_gravity="center"
               />
           <TextView
               android:id="@+id/tvTotalTime"
               android:layout_width="0dp"
               android:layout_height="match_parent"
               android:layout_weight="0.1"
               android:gravity="center|left"
               android:text="00:00"
               android:textSize="12dp"
               android:textColor="#FFFFFFFF"
               />
       </LinearLayout>
       <Button
           android:id="@+id/player"
           android:layout_width="45dp"
           android:layout_height="45dp"
           android:background="@drawable/ic_play_24"
           android:layout_centerInParent="true"
           />
   </RelativeLayout>
</FrameLayout>

2.编写VideoPlayerView.java文件

public class VideoPlayerView extends FrameLayout implements View.OnClickListener {
   private static final String TAG = "VideoPlayerView";

   private SurfaceView mSurfaceView;

   private MediaPlayer mMediaPlayer = null;

   private int currentPosition = 0;

   private SurfaceHolder mSurfaceHolder;

   private boolean isPlaying;

   private SeekBar mSeekBar;

   private Button mPlyer;

   private String mUrl;

   private TextView tvCurrentTime, tvTotalTime;

   private Handler handler = new Handler(Looper.getMainLooper());

   public VideoPlayerView(Context context) {
       this(context, null);
   }

   public VideoPlayerView(Context context, AttributeSet attrs) {
       this(context, attrs, 0);
   }

   public VideoPlayerView(Context context, AttributeSet attrs, int defStyleAttr) {
       super(context, attrs, defStyleAttr);
       init(context);
   }

   private void init(Context context) {
       initView(context);
       // 为SurfaceHolder添加回调
       mSurfaceHolder = mSurfaceView.getHolder();
       mSurfaceHolder.addCallback(callback);
       //设置Surface不维护自己的缓冲区，而是等待屏幕的渲染引擎将内容推送到界面
       mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
   }

   private void initView(Context context) {
       View view = LayoutInflater.from(context).inflate(R.layout.layout_video_player,null,false);
       mSurfaceView = view.findViewById(R.id.surfaceview);
       mSeekBar = view.findViewById(R.id.seekBar);
       mPlyer = view.findViewById(R.id.player);
       tvCurrentTime = view.findViewById(R.id.tvCurrentTime);
       tvTotalTime = view.findViewById(R.id.tvTotalTime);
       addView(view);
       mPlyer.setOnClickListener(this);
       mSeekBar.setOnSeekBarChangeListener(change);
   }

   private SurfaceHolder.Callback callback = new SurfaceHolder.Callback() {
       @Override
       public void surfaceCreated(@NonNull SurfaceHolder holder) {
           LogUtil.info(TAG, "surfaceCreated被创建");
           if (currentPosition > 0) {
               // 创建SurfaceHolder的时候，如果存在上次播放的位置，则按照上次播放位置进行播放
               play(currentPosition);
               currentPosition = 0;
           }
       }

       @Override
       public void surfaceChanged(@NonNull SurfaceHolder holder, int format, int width, int height) {
           LogUtil.info(TAG, "surfaceChanged大小改变");
       }

       @Override
       public void surfaceDestroyed(@NonNull SurfaceHolder holder) {
           LogUtil.info(TAG, "surfaceDestroyed被销毁");
           if (mMediaPlayer != null && mMediaPlayer.isPlaying()) {
               currentPosition = mMediaPlayer.getCurrentPosition();
               mMediaPlayer.stop();
               mMediaPlayer.release();
           }
       }
   };

   private void play(int currentPosition) {
       if (mMediaPlayer != null) {
           mMediaPlayer.seekTo(currentPosition);
       }
   }

   /**
    * 播放本地视频
    * @param mUrl
    */
   public void setPlayerVideo(String mUrl) {
       this.mUrl = mUrl;
       LogUtil.info(TAG, "setPlayerVideo mUrl: " + mUrl);
       if (mUrl.contains("http")) {
           showRemoteVideo(0);
       } else {
           playerLocalView(0);
       }
   }

   // 播放本地视频
   private void playerLocalView(final int msec) {
       LogUtil.info(TAG, " 获取视频文件地址");
       String path = mUrl;
       File file = new File(path);
       if (!file.exists()) {
           Toast.makeText(AppContextUtil.getContext(), "视频文件路径错误", Toast.LENGTH_SHORT).show();
           return;
       }
       LogUtil.info(TAG, "指定视频源路径");
       try {
           mMediaPlayer = new MediaPlayer();
           mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
           // 设置播放的视频源
           mMediaPlayer.setDataSource(file.getAbsolutePath());
           // 设置显示视频的SurfaceHolder
           mMediaPlayer.setDisplay(mSurfaceHolder);
           LogUtil.info(TAG, "开始装载");
           mMediaPlayer.prepareAsync();
           mMediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {

               @Override
               public void onPrepared(MediaPlayer mp) {
                   LogUtil.info(TAG, "装载完成");
                   mMediaPlayer.start();
                   // 按照初始位置播放
                   mMediaPlayer.seekTo(msec);
                   // 设置进度条的最大进度为视频流的最大播放时长
                   mSeekBar.setMax(mMediaPlayer.getDuration());
                   tvCurrentTime.setText(DateUtil.getDate(msec, DateUtil.PARAMETER));
                   tvTotalTime.setText(DateUtil.getDate(mMediaPlayer.getDuration(), DateUtil.PARAMETER));
                   // 开始线程，更新进度条的刻度
                   new Thread() {
                       @Override
                       public void run() {
                           try {
                               isPlaying = true;
                               while (isPlaying) {
                                   // 如果正在播放，没0.5.毫秒更新一次进度条
                                   int current = mMediaPlayer.getCurrentPosition();
                                   mSeekBar.setProgress(current);
                                   handler.post(new Runnable() {
                                       @Override
                                       public void run() {
                                           tvCurrentTime.setText(DateUtil.getDate(current, DateUtil.PARAMETER));
                                       }
                                   });

                                   sleep(500);
                               }
                           } catch (Exception e) {
                               e.printStackTrace();
                           }
                       }
                   }.start();

               }
           });
           mMediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {

               @Override
               public void onCompletion(MediaPlayer mp) {
                   // 在播放完毕被回调
                   mPlyer.setEnabled(true);
               }
           });

           mMediaPlayer.setOnErrorListener(new MediaPlayer.OnErrorListener() {

               @Override
               public boolean onError(MediaPlayer mp, int what, int extra) {
                   // 发生错误重新播放
                   play(0);
                   isPlaying = false;
                   return false;
               }
           });
       } catch (Exception e) {
           e.printStackTrace();
       }
   }

   // 播放远程视频
   private void showRemoteVideo(final int msec) {
       String videoUrl2 = mUrl;
       Uri uri = Uri.parse(videoUrl2);
       try {
           mMediaPlayer = new MediaPlayer();
           mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
           // 设置播放的视频源
           mMediaPlayer.setDataSource(AppContextUtil.getContext(), uri);
           // 设置显示视频的SurfaceHolder
           mMediaPlayer.setDisplay(mSurfaceHolder);
           LogUtil.info(TAG, "开始装载");
           mMediaPlayer.prepareAsync();
           mMediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
               @Override
               public void onPrepared(MediaPlayer mp) {
                   LogUtil.info(TAG, "装载完成");
                   mMediaPlayer.start();
                   // 按照初始位置播放
                   mMediaPlayer.seekTo(msec);
                   // 设置进度条的最大进度为视频流的最大播放时长
                   mSeekBar.setMax(mMediaPlayer.getDuration());
                   tvCurrentTime.setText(DateUtil.getDate(msec, DateUtil.PARAMETER));
                   tvTotalTime.setText(DateUtil.getDate(mMediaPlayer.getDuration(), DateUtil.PARAMETER));
                   // 开始线程，更新进度条的刻度
                   new Thread() {
                       @Override
                       public void run() {
                           try {
                               isPlaying = true;
                               while (isPlaying) {
                                   // 如果正在播放，没0.5.毫秒更新一次进度条
                                   int current = mMediaPlayer.getCurrentPosition();
                                   mSeekBar.setProgress(current);
                                   handler.post(new Runnable() {
                                       @Override
                                       public void run() {
                                           tvCurrentTime.setText(DateUtil.getDate(current, DateUtil.PARAMETER));
                                       }
                                   });

                                   sleep(500);
                               }
                           } catch (Exception e) {
                               e.printStackTrace();
                           }
                       }
                   }.start();
               }
           });
           mMediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {

               @Override
               public void onCompletion(MediaPlayer mp) {
                   mp.release();
                   mp = null;
                   // 在播放完毕被回调
                   mPlyer.setEnabled(true);
               }
           });

           mMediaPlayer.setOnErrorListener(new MediaPlayer.OnErrorListener() {

               @Override
               public boolean onError(MediaPlayer mp, int what, int extra) {
                   // 发生错误重新播放
                   play(0);
                   isPlaying = false;
                   return false;
               }
           });
       } catch (Exception e) {
           e.printStackTrace();
       }
   }

   private SeekBar.OnSeekBarChangeListener change = new SeekBar.OnSeekBarChangeListener() {

       @Override
       public void onStopTrackingTouch(SeekBar seekBar) {
           // 当进度条停止修改的时候触发
           // 取得当前进度条的刻度
           int progress = seekBar.getProgress();
//            if (mMediaPlayer != null && mMediaPlayer.isPlaying()) {
               // 设置当前播放的位置
               mMediaPlayer.seekTo(progress);
               tvCurrentTime.setText(DateUtil.getDate(progress, DateUtil.PARAMETER));
//            }
       }

       @Override
       public void onStartTrackingTouch(SeekBar seekBar) {

       }

       @Override
       public void onProgressChanged(SeekBar seekBar, int progress,
                                     boolean fromUser) {

       }
   };

   @Override
   public void onClick(View v) {
       if (v.getId() == R.id.player) {
           if (mMediaPlayer == null) {
               return;
           }
           if (mMediaPlayer.isPlaying()) {
               mMediaPlayer.pause();
               mPlyer.setBackgroundResource(R.drawable.ic_play_24);
           } else {
               mMediaPlayer.start();
               mPlyer.setBackgroundResource(R.drawable.ic_pause_24);
           }
       }
   }

   public void pause () {
       if (mMediaPlayer == null) {
           return;
       }
       if (mMediaPlayer.isPlaying()) {
           mMediaPlayer.pause();
           mPlyer.setBackgroundResource(R.drawable.ic_pause_24);
       }
   }

   public void destroy() {
       if (mMediaPlayer != null) {
           mMediaPlayer.stop();
           mMediaPlayer.reset();
           mMediaPlayer.release();
           mMediaPlayer = null;
       }
       isPlaying = false;
       LogUtil.info(TAG, "MediaPlayer is release");
   }
}

该类主要做了如下工作：
1).初始化控件；
2).SurfaceHolder回调监听；
3).播放本地视频；
4).播放网络视频；
5).常用SeekBar显示进度及改变进度；
6).额外工作，播放、暂停、总时长、当前时长的View控件。

3.编写Activity的布局文件activity_player_video.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/player_layout"
    />

从上面可以看出，里面没有任何子view，仅仅声明FrameLayout和id即可。

4.PlayerVideoActivity.java

public class PlayerVideoActivity extends Activity {
    private FrameLayout playerLayout;

    private VideoPlayerView videoPlayerView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_player_video);
        initPlayer();
    }

    private void initPlayer() {
        String localPath = Environment.getExternalStorageDirectory() +"/xlk-player.mp4";
        playerLayout = findViewById(R.id.player_layout);
        videoPlayerView = new VideoPlayerView(this);
        playerLayout.addView(videoPlayerView);
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                //这里传入本地视频的路径或者网络视频的url
                videoPlayerView.setPlayerVideo(localPath);
            }
        },500);
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (videoPlayerView != null) {
            videoPlayerView.pause();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (videoPlayerView != null) {
            videoPlayerView.destroy();
            videoPlayerView = null;
        }
    }
}

上面实例化一个VideoPlayerView，然后通过VideoPlayerView对象来调用setPlayerVideo的方法传入本地视频的路径或者网络视频的url,实现音视频播放器，运行此项目，效果如开头显示的一幕。
自定义View播放器已经实现了，但我们需要掌握MediaPlayer的初始化过程是怎么样的，MediaPlayer做了哪些工作，音视频数据如何渲染到SurfaceView上面的，这需要把MediaPlayer框架原理搞清楚。就像下面的。

3.png

每个方法调用过程是怎么样子的，做了哪些工作，而不是简单写几行代码就可以实现播放视频或者音频。
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