Android音频开发(三)：使用ExoPlayer播放音频

一、Android音频开发(一)：音频基础知识
二、Android音频开发(二)：录制音频(WAV及MP3格式)
三、Android音频开发(三)：使用ExoPlayer播放音频
四、Android音频开发(四)：音频播放模式
五、Android音频开发(五)：感应(息屏/亮屏)管理

附GitHub源码：MultimediaExplore

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备注：ExoPlayer的解码是依赖Android系统提供的原生解码模块MediaCodec进行视频和音频解码的。关于ExoPlayer具体可参考：ExoPlayer

 一、音频播放的权限及依赖：

音频播放可能涉及到的权限：

    <uses-permission android:name="android.permission.INTERNET" />
    <!--音频模式切换权限-->
    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>

    <!--唤屏/息屏权限-->
    <uses-permission android:name="android.Manifest.permission.DEVICE_POWER"/>
    <uses-permission android:name="android.permission.WAKE_LOCK"/>

音频播放器所需依赖： 

    // 多媒体播放器
    implementation 'com.google.android.exoplayer:exoplayer-core:2.15.0'
    implementation 'com.google.android.exoplayer:exoplayer-ui:2.15.0'
    implementation 'com.google.android.exoplayer:exoplayer-hls:2.15.0'
    implementation 'com.google.android.exoplayer:exoplayer-dash:2.15.0'
    implementation 'com.google.android.exoplayer:exoplayer-transformer:2.15.0'
    implementation 'com.google.android.exoplayer:exoplayer-rtsp:2.15.0'
    implementation 'com.google.android.exoplayer:exoplayer-smoothstreaming:2.15.0'

二、ExoPlayer实例生成： 

生成SimpleExoPlayer实例，然后将build好的音频资源set到音频播放器即可进行播放。这里需要注意一点的是如果要获取音频的播放进度，需要生成一个如下图的handlerInner Handler实例，然后将其addEventListener中。否则如果直接使用从外部传过来的hander，所得到的音频播放进度会一直是0。

    public void prepareAudioPlayer(Context context, Handler handler, Uri uri) {
        if (player == null) {
            player = new SimpleExoPlayer.Builder(context).build();
        }
        mediaSource = AudioMediaSourceManager.getInstance().buildMediaSource(uri, isLocalResource);
        if (mediaSource == null || player == null) {
            return;
        }

        if (handlerInner == null) {
            handlerInner = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    super.handleMessage(msg);
                    Message msgOuter = new Message();
                    if (msg.what == WHAT_POSITION) {
                        currentPosition = player.getCurrentPosition() / 1000;
                        contentPosition = player.getContentPosition() / 1000;
                        contentBufferedPosition = player.getContentBufferedPosition() / 1000;
                        Log.d(TAG, "-----> currentPosition:" + currentPosition + " contentPosition:" + contentPosition + " contentBufferedPosition:" + contentBufferedPosition);
                        HashMap<String, Long> hashMap = new HashMap<>();
                        hashMap.put("currentPosition", currentPosition);
                        hashMap.put("contentPosition", contentPosition);
                        hashMap.put("contentBufferedPosition", contentBufferedPosition);
                        msgOuter.what = WHAT_POSITION;
                        msgOuter.obj = hashMap;
                        handler.sendMessage(msgOuter);
                        if (currentPosition < duration) {
                            sendEmptyMessageDelayed(WHAT_POSITION, 300);
                        }
                    } else if (msg.what == WHAT_DURATION) {
                        msgOuter.obj = msg.obj;
                        handler.sendMessage(msgOuter);
                    }
                }
            };
        }

        mediaSource.addEventListener(handlerInner, new MediaSourceEventListener() {

            @Override
            public void onLoadStarted(int windowIndex, @Nullable MediaSource.MediaPeriodId mediaPeriodId, LoadEventInfo loadEventInfo, MediaLoadData mediaLoadData) {
                Log.d(TAG, "onLoadStarted ---> duration:" + duration);
            }

            @Override
            public void onLoadCompleted(int windowIndex, @Nullable MediaSource.MediaPeriodId mediaPeriodId, LoadEventInfo loadEventInfo, MediaLoadData mediaLoadData) {
                mediaSource.removeEventListener(this);

                //发送时长消息
                duration = player.getDuration() / 1000;
                Message msg = new Message();
                msg.what = WHAT_DURATION;
                msg.obj = duration;
                handlerInner.sendMessage(msg);

                //发送position消息
                Message msgPos = new Message();
                msgPos.what = WHAT_POSITION;
                handlerInner.sendMessage(msgPos);

                Log.d(TAG, "onLoadCompleted ---> duration:" + duration);
            }
        });
        player.setMediaSource(mediaSource);
        player.addListener(new Player.Listener() {

            @Override
            public void onPlayWhenReadyChanged(boolean playWhenReady, int reason) {
                Log.d(TAG, "onPlayWhenReadyChanged---> playWhenReady:" + playWhenReady);
                AudioPlayer.this.playWhenReady = playWhenReady;
            }

            @Override
            public void onPlaybackStateChanged(int playbackState) {
                Log.d(TAG, "onPlaybackStateChanged---> playbackState:" + playbackState);
                switch (playbackState) {
                    case Player.STATE_READY:
                        Log.d(TAG, "STATE_READY");
                        break;
                    case Player.STATE_BUFFERING:
                        Log.d(TAG, "STATE_BUFFERING");
                        break;
                    case Player.STATE_ENDED:
                        Log.d(TAG, "STATE_ENDED");
                        audioStatus = AudioPlayStatus.AUDIO_STOP;
                        AudioModeManager.getInstance().abandonAudioFocus();
                        break;
                    case Player.STATE_IDLE:
                        Log.d(TAG, "STATE_IDLE");
                        audioStatus = AudioPlayStatus.AUDIO_IDLE;
                        AudioModeManager.getInstance().abandonAudioFocus();
                        break;
                }
            }

            @Override
            public void onIsPlayingChanged(boolean isPlaying) {
                Log.d(TAG, "onIsPlayingChanged---> isPlaying:" + isPlaying);
                if (isPlaying) {
                    audioStatus = AudioPlayStatus.AUDIO_START;
                } else {

                }
            }
        });

        player.prepare();
    }

三、音频播放生命周期方法：

    public void play() {
        Log.d(TAG, "play");
        if (player == null) {
            return;
        }
        AudioModeManager.getInstance().requestAudioFocus();
        if (playWhenReady) {
            if (!player.isPlaying()) {
                player.setPlayWhenReady(true);
            }
        } else {
            player.prepare();
            player.setPlayWhenReady(true);
        }
        audioStatus = AudioPlayStatus.AUDIO_START;
    }

    public void pause() {
        Log.d(TAG, "pause");
        if (player == null) {
            return;
        }
        AudioModeManager.getInstance().abandonAudioFocus();
        if (player.isPlaying()) {
            player.pause();
        }
        audioStatus = AudioPlayStatus.AUDIO_PAUSE;
    }

    public void stop() {
        Log.d(TAG, "stop");
        if (player == null) {
            return;
        }
        AudioModeManager.getInstance().abandonAudioFocus();
        player.stop();
        audioStatus = AudioPlayStatus.AUDIO_STOP;
    }

    public void cancel() {
        Log.d(TAG, "cancel");
    }

    public void release() {
        Log.d(TAG, "release");
        if (player == null) {
            return;
        }
        AudioModeManager.getInstance().abandonAudioFocus();
        player.release();
        if (handlerInner != null) {
            handlerInner.removeCallbacksAndMessages(null);
        }
        audioStatus = AudioPlayStatus.AUDIO_RELEASE;
    }

四、音频播放管理AudioPlayManager：

类似AudioRecordManager的作用，音频播放器全局单例，代码略。