EXOPlayer简要学习及应用

本想着上效果图的，可惜图片太大了不允许上传参观移步GitHub

EXOPlayer是Google官方开源的一种播放器官方介绍 ，能够支持DASH, SmoothStreaming 和 HLS，可惜不能支持Adobe的rtsp、rtmp（有时间我会把B站开源播放器放上来IjkPlayer，那才叫功能强大且易上手这是后话。毕竟EXOPlayer是Google的亲儿子，我也是先应用的它而后转去ijkPlayer的）。至于以上内容如有内容不明白的可以自行查询不是我这里的重点，都是些视频相关概念，我还是着重应用。

我项目应用的EXOPlayer版本为2.0.0，此时此刻最新的版本为2.5.1。不是我不想用最新的，而是在我刚开始接触看2.5.1源码的时候，项目中分了多个Module且功能都比较独立，应用的时候必须引用多个模块，想短时间利用来开发难度很大，需要了解的内部逻辑很多，demo估计还没看完就懵了。



相反2.0.0版本只需要

compile 'com.google.android.exoplayer:exoplayer:r2.0.0'

我所抽取的类就两个PlayerActivity（播放界面）和EventLogger（日志打印），应用的时候一个Intent过去就解决了。

以下是干货

Intent：

private void goActivity(String url) {
Intent intent = new Intent(MainActivity.this, PlayerActivity.class);
intent.setData(Uri.parse(url)); //传入视频地址  在PlayerActivity内会根据后缀的不同区分不同的资源
intent.setAction(PlayerActivity.ACTION_VIEW);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { //ShareElement 效果
startActivity(intent, ActivityOptions.makeSceneTransitionAnimation(MainActivity.this, imageView, "shareImage").toBundle());
} else {
startActivity(intent);
}
}

PlayerActivity的控件SimpleExoPlayerView：SimpleExoPlayerView extends FrameLayout可以理解为播放控件，里面包含了播放控制控件PlaybackControlView。

public SimpleExoPlayerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);

...
//控件初始化逻辑
...

//这里才是关键 其实我们看到的视频界面 无非是TextureView 或SurfaceView 这里以下有逻辑解释
View view = useTextureView ? new TextureView(context) : new SurfaceView(context);
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT);
view.setLayoutParams(params);
surfaceView = view;
layout.addView(surfaceView, 0);
}

控件初始化完成，需要输入player

public void setPlayer(SimpleExoPlayer player) {
...
//重置操作
...

this.player = player;

if (player != null) {//我们看到的就是这两个控件
if (surfaceView instanceof TextureView) {
player.setVideoTextureView((TextureView) surfaceView);
} else if (surfaceView instanceof SurfaceView) {
player.setVideoSurfaceView((SurfaceView) surfaceView);
}
player.setVideoListener(componentListener);
player.addListener(componentListener);
player.setTextOutput(componentListener);
}
setUseController(useController);
}

public void setUseController(boolean useController) {
this.useController = useController;
//controller 是控制控件 播放暂停之类
if (useController) {
//这种设计方式比较好 不是给player设置各种控件 而是让控件去监听变化  松耦合思想
controller.setPlayer(player);
} else {
controller.hide();
controller.setPlayer(null);
}
}

PlayerActivity的基本思路：

onCreate 初始化控件；

onNewIntent 释放原有player设置新数据

onStart onResume 初始化initializePlayer()

onPause onStop 释放releasePlayer()

关键就是以上几个方法，源码中冗长的代码是一些回调和抽离方法

private void initializePlayer() {
Intent intent = getIntent();
if (player == null) {
//数字证书相关  如果需求不需要的话可以移除
boolean preferExtensionDecoders = intent.getBooleanExtra(PREFER_EXTENSION_DECODERS, false);
UUID drmSchemeUuid = intent.hasExtra(DRM_SCHEME_UUID_EXTRA)
? UUID.fromString(intent.getStringExtra(DRM_SCHEME_UUID_EXTRA)) : null;
DrmSessionManager drmSessionManager = null;
if (drmSchemeUuid != null) {
String drmLicenseUrl = intent.getStringExtra(DRM_LICENSE_URL);
String[] keyRequestPropertiesArray = intent.getStringArrayExtra(DRM_KEY_REQUEST_PROPERTIES);
Map<String, String> keyRequestProperties;
if (keyRequestPropertiesArray == null || keyRequestPropertiesArray.length < 2) {
keyRequestProperties = null;
} else {
keyRequestProperties = new HashMap<>();
for (int i = 0; i < keyRequestPropertiesArray.length - 1; i += 2) {
keyRequestProperties.put(keyRequestPropertiesArray[i],
keyRequestPropertiesArray[i + 1]);
}
}
try {
drmSessionManager = buildDrmSessionManager(drmSchemeUuid, drmLicenseUrl,
keyRequestProperties);
} catch (UnsupportedDrmException e) {
int errorStringId = Util.SDK_INT < 18 ? R.string.error_drm_not_supported
: (e.reason == UnsupportedDrmException.REASON_UNSUPPORTED_SCHEME
? R.string.error_drm_unsupported_scheme : R.string.error_drm_unknown);

4000
showToast(errorStringId);
return;
}
}
//数字证书相关

eventLogger = new EventLogger();//日志打印
TrackSelection.Factory videoTrackSelectionFactory =
new AdaptiveVideoTrackSelection.Factory(BANDWIDTH_METER);
trackSelector = new DefaultTrackSelector(mainHandler, videoTrackSelectionFactory);
trackSelector.addListener(this);
trackSelector.addListener(eventLogger);
player = ExoPlayerFactory.newSimpleInstance(this, trackSelector, new DefaultLoadControl(),
drmSessionManager, preferExtensionDecoders);
player.addListener(this);
player.addListener(eventLogger);
player.setAudioDebugListener(eventLogger);
player.setVideoDebugListener(eventLogger);
player.setId3Output(eventLogger);
simpleExoPlayerView.setPlayer(player);
if (shouldRestorePosition) {
if (playerPosition == C.TIME_UNSET) {
player.seekToDefaultPosition(playerWindow);
} else {
player.seekTo(playerWindow, playerPosition);
}
}
player.setPlayWhenReady(shouldAutoPlay);
playerNeedsSource = true;
}
if (playerNeedsSource) {
String action = intent.getAction();
Uri[] uris;
String[] extensions;
if (ACTION_VIEW.equals(action)) {// 多个资源的话会无缝连接播放
uris = new Uri[]{intent.getData()};
extensions = new String[]{intent.getStringExtra(EXTENSION_EXTRA)};
} else if (ACTION_VIEW_LIST.equals(action)) {
String[] uriStrings = intent.getStringArrayExtra(URI_LIST_EXTRA);
uris = new Uri[uriStrings.length];
for (int i = 0; i < uriStrings.length; i++) {
uris[i] = Uri.parse(uriStrings[i]);
}
extensions = intent.getStringArrayExtra(EXTENSION_LIST_EXTRA);
if (extensions == null) {
extensions = new String[uriStrings.length];
}
} else {
showToast(getString(R.string.unexpected_intent_action, action));
return;
}
if (Util.maybeRequestReadExternalStoragePermission(this, uris)) {// 外部存储权限
// The player will be reinitialized if the permission is granted.
return;
}
MediaSource[] mediaSources = new MediaSource[uris.length];  //将URL组装成资源类
for (int i = 0; i < uris.length; i++) {
mediaSources[i] = buildMediaSource(uris[i], extensions[i]);
}
MediaSource mediaSource = mediaSources.length == 1 ? mediaSources[0]
: new ConcatenatingMediaSource(mediaSources);
player.prepare(mediaSource, !shouldRestorePosition);
playerNeedsSource = false;
}
}

//根据后缀区分资源类型
private MediaSource buildMediaSource(Uri uri, String overrideExtension) {
int type = Util.inferContentType(!TextUtils.isEmpty(overrideExtension) ? "." + overrideExtension
: uri.getLastPathSegment());
switch (type) {
case Util.TYPE_SS:
return new SsMediaSource(uri, buildDataSourceFactory(false),
new DefaultSsChunkSource.Factory(mediaDataSourceFactory), mainHandler, eventLogger);
case Util.TYPE_DASH:
return new DashMediaSource(uri, buildDataSourceFactory(false),
new DefaultDashChunkSource.Factory(mediaDataSourceFactory), mainHandler, eventLogger);
case Util.TYPE_HLS:
return new HlsMediaSource(uri, mediaDataSourceFactory, mainHandler, eventLogger);
case Util.TYPE_OTHER:
return new ExtractorMediaSource(uri, mediaDataSourceFactory, new DefaultExtractorsFactory(),
mainHandler, eventLogger);
default: {
throw new IllegalStateException("Unsupported type: " + type);
}
}
}

private void releasePlayer() {
if (player != null) {
shouldAutoPlay = player.getPlayWhenReady();
shouldRestorePosition = false;
Timeline timeline = player.getCurrentTimeline();
if (timeline != null) {
playerWindow = player.getCurrentWindowIndex();
Timeline.Window window = timeline.getWindow(playerWindow, new Timeline.Window());
if (!window.isDynamic) {
shouldRestorePosition = true;
playerPosition = window.isSeekable ? player.getCurrentPosition() : C.TIME_UNSET; //保存播放位置
}
}
player.release();
player = null;
trackSelector = null;
eventLogger = null;
}
}

简要介绍只能做到这种地步了，如果要自己应用或者学习的话多动手多改源码才是正道，不要妄想看一两篇文章就想搞懂。