Android13-播放多媒体文件

1.播放音频

使用MediaPlayer类来实现，该类对多种格式的音频提供了非常全面的控制，常用的控制方法有以下这些，图片来自《第一行代码2》

2017-04-13_17-22-25.png

• 以下是实现一个简单的播放、暂停功能的代码

  注：实现该功能前，需先声明读取sdcard的权限

• activity的代码如下

public class MainActivity extends AppCompatActivity {
        private MediaPlayer mediaPlayer = new MediaPlayer();
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.layout_main);
            Button play = (Button) findViewById(R.id.play);
            Button pause = (Button) findViewById(R.id.pause);
            Button stop = (Button) findViewById(R.id.stop);
            //播放按钮的点击事件
            play.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (!mediaPlayer.isPlaying()) {
                        mediaPlayer.start();
                    }
                }
            });
            //暂停按钮的点击事件
            pause.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (mediaPlayer.isPlaying()) {
                        mediaPlayer.pause();
                    }
                }
            });
            //停止按钮的点击事件
            stop.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (mediaPlayer.isPlaying()) {
                        mediaPlayer.reset();//停止播放
                        initMediaPlayer();
                    }
                }
            });
            //判断是否已授权
            if (ContextCompat.checkSelfPermission(MainActivity.this, WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                //未授权
                //发起授权请求ActivityCompat.requestPermissions(MainActivity.this, new String[] { WRITE_EXTERNAL_STORAGE }, 1);
            } else {
                initMediaPlayer();//初始化MediaPlayer
            }
        }
        private void initMediaPlayer() {
            try {
                //播放sdcard根目录下的music.mp3
                File file = new File(Environment.getExternalStorageDirectory(), "music.mp3");
                mediaPlayer.setDataSource(file.getPath());
                mediaPlayer.prepare();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        //授权请求结束时调用
        @Override
        public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
            switch (requestCode) {
                case 1:
                    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                        initMediaPlayer();
                    } else {
                        Toast.makeText(this,"拒绝权限将无法使用程序", Toast.LENGTH_SHORT).show();
                    }
                    break;
                default:
                    break;
            }
        }
        @Override
        protected void onDestroy() {
            super.onDestroy();
            if (mediaPlayer != null) {
                mediaPlayer.stop();
                mediaPlayer.release();
            }
        }
}

• 界面如下

2017-04-13_18-19-41.png

2.播放视频文件

播放视频跟播放音频类似，跟播放音频不同的是，播放视频需在布局文件中加入VideoView，播放视频使用的是VideoView类来实现，以下是以下常用的控制方法，图片来自《第一行代码第二版》

2017-04-13_17-59-50.png

• 以下是实现一个简单的播放暂停视频功能的代码

  和播放音频一样需要在Manifest文件中声明读取sd卡的权限。

• activity中的代码如下

    public class MainActivity extends AppCompatActivity {
        private VideoView videoView;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
setContentView(R.layout.layout_main);
            videoView = (VideoView) findViewById(R.id.video_view);
            Button play = (Button) findViewById(R.id.play);
            Button pause = (Button) findViewById(R.id.pause);
            Button replay = (Button) findViewById(R.id.replay);
            //点击播放
            play.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (!videoView.isPlaying()) {
                        videoView.start();
                    }
                }
            });
            //点击暂停
            pause.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (videoView.isPlaying()) {
                    videoView.pause();
                    }
                }
            });
            //点击重播
        replay.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (videoView.isPlaying()) {
                        videoView.resume();
                    }
                }
            });
            //授权申请
            if (ContextCompat.checkSelfPermission(MainActivity.this, WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(MainActivity.this, new String[] { WRITE_EXTERNAL_STORAGE }, 1);
            } else {
                initVideoPath();//初始化MediaPlayer
            }
        }
        //初始化MediaPlayer
        private void initVideoPath() {
            File file = new File(Environment.getExternalStorageDirectory(), "movie.mp4");
            videoView.setVideoPath(file.getPath());
        }
        //授权请求结束时调用
        @Override
        public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
            switch (requestCode) {
                case 1:
                    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                        initVideoPath();
                    } else {
                    Toast.makeText(this, "你拒绝了授权申请", Toast.LENGTH_SHORT);
                    }
            }
        }
}