概述
Android多媒体框架支持各种常见的媒体类型，可以很容易地将音频、视频和图像集成到App中。通过MediaPlayer Api，可以从应用程序资源（RAW）、文件系统或网络上数据流资源来播放音频或视频。本文演示了如何通过Api播放音频和视频文件，来获得良好性能和愉快的用户体验，仅供学习分享使用，如有不足之处，还请指正。
涉及知识点
- MediaPlayer 可以用来控制audio/video文件或流播放的类。通过此类，可以方便的控制音频/视频文件的播放，暂停和停止等操作。
- Uri 统一资源标识符(Uniform Resource Identifier，或URI)是一个用于标识某一互联网资源名称的字符串。
- VideoView 自带的一种播放视频的组件。
- SurfaceView 可以通过后台绘制显示的视图组件。
Activity中播放音频
页面上播放音频文件，步骤如下：
1. 准备资源文件，并播放
1 private MediaPlayer mMediaPlayer;
2
3 /**
4 * 开始
5 * @param v
6 */
7 public void bn_start(View v){
8 if(mMediaPlayer==null) {
9 ready();
10 }
11 mMediaPlayer.start();
12 }
13
14 /**
15 * 创建MediaPlayer并到prepare状态
16 */
17 private void ready(){
18 if(mMediaPlayer==null){
19 mMediaPlayer=new MediaPlayer();//Idle
20 //Log.i("TAG", "ready: "+filePath);
21 File file=new File(Environment.getExternalStorageDirectory(),"goldfallen.mp3");
22 Log.i("TAG", "ready: "+file.getPath());
23 Log.i("TAG", "ready: "+file.exists());
24 Uri uri= Uri.fromFile(file);
25 try {
26 mMediaPlayer.setDataSource(AudioActivity.this,uri);
27 mMediaPlayer.prepare();//Prepared
28 } catch (IOException e) {
29 Log.i("TAG", "ready: "+ e.getMessage());
30 e.printStackTrace();
31 }
32 }
33 }
2. 暂停播放
1 /**
2 * 暂停
3 * @param v
4 */
5 public void bn_pause(View v){
6 if(mMediaPlayer!=null && mMediaPlayer.isPlaying()){
7 mMediaPlayer.pause();
8 }
9 }
3. 停止
1 /**
2 * 停止
3 * @param v
4 */
5 public void bn_stop(View v){
6 if(mMediaPlayer!=null && mMediaPlayer.isPlaying()){
7 mMediaPlayer.stop();
8 mMediaPlayer.release();
9 mMediaPlayer=null;
10 }
11 }
4. 释放资源（当页面销毁时，播放资源也要同时释放）
1 @Override
2 protected void onDestroy() {
3 if(mMediaPlayer!=null && mMediaPlayer.isPlaying()){
4 mMediaPlayer.stop();
5 mMediaPlayer.release();
6 mMediaPlayer=null;
7 }
8 super.onDestroy();
9 }
5. 通过静态函数创建对象
1 /**
2 * D:\Android\Project\DemoMedia\app\src\main\res\raw\A2012.mp3:
3 * Error: 'A' is not a valid file-based resource name character:
4 * File-based resource names must contain only lowercase a-z, 0-9, or underscore
5 */
6 private void ready2(){
7 if(mMediaPlayer==null){
8 mMediaPlayer= MediaPlayer.create(this,R.raw.ab2012);
9 }
10 }
通过服务来播放音频
当页面关闭时，音频文件还可以在后台播放。步骤如下：
1. 定义后台服务，当服务启动时，创建MediaPlayer对象，并注册服务接收对象。
1 public class AudioService extends Service {
2
3 private MediaPlayer mMediaPlayer;
4
5 private OperatorReceiver mReceiver;
6
7 public AudioService() {
8 }
9
10 @Override
11 public void onCreate() {
12 super.onCreate();
13 mMediaPlayer=new MediaPlayer();
14 mReceiver=new OperatorReceiver();
15 IntentFilter filter=new IntentFilter("operator.receiver");
16 registerReceiver(mReceiver,filter);
17 }
18
19 @Override
20 public IBinder onBind(Intent intent) {
21 return null;
22 }
23
24 @Override
25 public int onStartCommand(Intent intent, int flags, int startId) {
26 Log.i("TAG", "onStartCommand: ----ready ");
27 ready();
28 return super.onStartCommand(intent, flags, startId);
29 }
30
31 @Override
32 public void onDestroy() {
33 if(mMediaPlayer!=null && mMediaPlayer.isPlaying()){
34 mMediaPlayer.stop();
35 }
36 if(mMediaPlayer!=null){
37 mMediaPlayer.release();
38 mMediaPlayer=null;
39 }
40 unregisterReceiver(mReceiver);
41 super.onDestroy();
42 }
43
44 private void start(){
45 mMediaPlayer.start();
46 }
47
48 private void pause(){
49 mMediaPlayer.pause();
50 }
51
52 private void stop(){
53 mMediaPlayer.stop();
54 ready();
55 }
56
57 private void ready(){
58 mMediaPlayer.reset();
59 try {
60 String filePath= Environment.getExternalStorageDirectory()+"/ab2012.mp3";
61 Log.i("TAG", "ready: "+filePath);
62 File file=new File(filePath);
63 if(file.exists()) {
64 mMediaPlayer.setDataSource(filePath);
65 mMediaPlayer.prepare();
66 }else{
67 Log.i("TAG", "ready: 文件不存在 ");
68 }
69 } catch (IOException e) {
70 Log.i("TAG", "ready: "+e.getMessage());
71 e.printStackTrace();
72 }
73 }
74 }
2. 操作接收者定义如下：
1 /**
2 * 操作接收器
3 */
4 class OperatorReceiver extends BroadcastReceiver
5 {
6 @Override
7 public void onReceive(Context context, Intent intent) {
8 int cmd=intent.getIntExtra("cmd",-1);
9 Log.i("TAG", "onReceive: "+cmd);
10 switch (cmd){
11 case Tools.PLAY:
12 start();
13 break;
14 case Tools.PAUSE:
15 pause();
16 break;
17 case Tools.STOP:
18 stop();
19 break;
20 default:
21 start();
22 break;
23
24 }
25 }
26 }
3. 启动服务
1 Intent intent =new Intent(this,AudioService.class);
2 startService(intent);
4. 前台Activity通过发送广播命令进行控制音频的播放与暂停
1 /**
2 * 开始
3 * @param v
4 */
5 public void bn_start(View v){
6 Intent intent=new Intent("operator.receiver");
7 intent.putExtra("cmd",Tools.PLAY);
8 sendBroadcast(intent);
9 Log.i("TAG", "bn_start: "+"service");
10 }
11
12 /**
13 * 暂停
14 * @param v
15 */
16 public void bn_pause(View v){
17 Intent intent=new Intent("operator.receiver");
18 intent.putExtra("cmd",Tools.PAUSE);
19 sendBroadcast(intent);
20 }
21
22 /**
23 * 停止
24 * @param v
25 */
26 public void bn_stop(View v){
27 Intent intent=new Intent("operator.receiver");
28 intent.putExtra("cmd",Tools.STOP);
29 sendBroadcast(intent);
30 }
5.通过后台服务的方式，需要在AndroidManifest.xml文件中进行注册
1 <service
2 android:name=".AudioService"
3 android:enabled="true"
4 android:exported="true">
5 </service>
通过VideoView来播放视频
通过VideoView进行播放视频文件，只需要设置资源URI即可，具体如下：
1 private VideoView mVideoView;
2 @Override
3 protected void onCreate(Bundle savedInstanceState) {
4 super.onCreate(savedInstanceState);
5 setContentView(R.layout.activity_video);
6 mVideoView= (VideoView) this.findViewById(R.id.vv_info);
7 //设置路径
8 File file=new File(Environment.getExternalStorageDirectory(),"DCIM/Camera/VID20190629142614.mp4");
9 Log.i("TAG", "onCreate: "+file.getPath());
10 if(!file.exists()){
11 Log.i("TAG", "onCreate: 文件不存在");
12 }
13 Uri uri=Uri.fromFile(file);
14 mVideoView.setVideoURI(uri);
15 //设置Media Controller
16 MediaController controller=new MediaController(this);
17 mVideoView.setMediaController(controller);
18 //获取焦点
19 mVideoView.requestFocus();
20 mVideoView.start();
21 //设置播放完成事件
22 mVideoView.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
23 @Override
24 public void onCompletion(MediaPlayer mp) {
25 Toast.makeText(VideoActivity.this, "播放完毕", Toast.LENGTH_SHORT).show();
26 }
27 });
28 }
通过MediaPlayer来播放视频
通过MediaPlayer来播放视频文件，然后通过SurfaceView来显示视频内容，具体步骤如下：
1.启动，通过setDisplay来设置显示内容
1 public void bn_start(View view) {
2 mMediaPlayer.reset();//到Idle状态
3 //设置路径
4 File file=new File(Environment.getExternalStorageDirectory(),"DCIM/Camera/VID20190629142614.mp4");
5 Log.i("TAG", "onCreate: "+file.getPath());
6 if(!file.exists()){
7 Log.i("TAG", "onCreate: 文件不存在");
8 } else {
9 Log.i("TAG", "onCreate: 文件存在 ");
10 }
11 Uri uri=Uri.fromFile(file);
12 try {
13 mMediaPlayer.setDataSource(this,uri);
14 mMediaPlayer.setDisplay(mSurfaceView.getHolder());
15 mMediaPlayer.prepare();
16 mMediaPlayer.start();
17 } catch (IOException e) {
18 e.printStackTrace();
19 }
20 }
2. 暂停与停止
1 public void bn_pause(View view){
2 if(mMediaPlayer.isPlaying()){
3 mMediaPlayer.pause();
4 }
5 }
6
7 public void bn_stop(View view){
8 if(mMediaPlayer.isPlaying()){
9 mMediaPlayer.stop();
10 }
11 }
3. 资源释放
1 @Override
2 protected void onDestroy() {
3 if(mMediaPlayer!=null && mMediaPlayer.isPlaying()){
4 mMediaPlayer.stop();
5 }
6 if(mMediaPlayer!=null){
7 mMediaPlayer.release();
8 mMediaPlayer=null;
9 }
10 super.onDestroy();
11 }
权限设置
如果要播放视频，需要相应的权限设置，并在安装时获取请求权限
1 <uses-permission android:name="android.permission.INTERNET"/>
2 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
3 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
4 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
备注
合抱之木，生于毫末；九层之台，起于垒土；千里之行，始于足下。
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