我正在寻找在 ExoPlayer 中实现缓存的任何示例。
ExoPlayer 在它的库中有关于缓存的不同类，Google 在这个video 中解释说我们可以使用 CacheDataSource 类来实现它，但 Google 没有提供任何关于它的演示。不幸的是，这似乎使用起来相当复杂，所以我目前正在寻找示例（在 Google 上没有成功）。
有没有人成功或有任何有用的信息？谢谢。
【问题讨论】：
标签： android caching media exoplayer
这是 ExoPlayer 2.+ 的解决方案
创建自定义缓存数据源工厂
public class CacheDataSourceFactory implements DataSource.Factory {
private final Context context;
private final DefaultDataSourceFactory defaultDatasourceFactory;
private final long maxFileSize, maxCacheSize;
public CacheDataSourceFactory(Context context, long maxCacheSize, long maxFileSize) {
super();
this.context = context;
this.maxCacheSize = maxCacheSize;
this.maxFileSize = maxFileSize;
String userAgent = Util.getUserAgent(context, context.getString(R.string.app_name));
DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
defaultDatasourceFactory = new DefaultDataSourceFactory(this.context,
bandwidthMeter,
new DefaultHttpDataSourceFactory(userAgent, bandwidthMeter));
}
@Override
public DataSource createDataSource() {
LeastRecentlyUsedCacheEvictor evictor = new LeastRecentlyUsedCacheEvictor(maxCacheSize);
SimpleCache simpleCache = new SimpleCache(new File(context.getCacheDir(), "media"), evictor);
return new CacheDataSource(simpleCache, defaultDatasourceFactory.createDataSource(),
new FileDataSource(), new CacheDataSink(simpleCache, maxFileSize),
CacheDataSource.FLAG_BLOCK_ON_CACHE | CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR, null);
}
}
还有玩家
BandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
TrackSelection.Factory videoTrackSelectionFactory =
new AdaptiveTrackSelection.Factory(bandwidthMeter);
TrackSelector trackSelector = new DefaultTrackSelector(videoTrackSelectionFactory);
SimpleExoPlayer exoPlayer = ExoPlayerFactory.newSimpleInstance(this, trackSelector);
MediaSource audioSource = new ExtractorMediaSource(Uri.parse(url),
new CacheDataSourceFactory(context, 100 * 1024 * 1024, 5 * 1024 * 1024), new DefaultExtractorsFactory(), null, null);
exoPlayer.setPlayWhenReady(true);
exoPlayer.prepare(audioSource);
效果很好。
【讨论】：
默认情况下，ExoPlayer 不缓存媒体（视频、音频等）。例如，如果你想播放一个在线视频文件，每次 ExoPlayer 都会打开一个连接，读取数据然后播放它。
幸运的是，它为我们提供了一些接口和实现类来支持在我们的应用中缓存媒体。
您可以编写自己的缓存来实现 ExoPlayer 的给定接口。为了简单起见，我将指导您如何使用实现类来启用缓存。
步骤 1： 指定一个包含您的媒体文件的文件夹，在 Android 中对于较小的缓存文件夹（小于 1MB），您应该使用getCacheDir，否则您可以指定您喜欢的缓存文件夹，以getFileDir 为例。
第 2 步：指定缓存文件夹的大小，以及达到该大小时的策略。有 2 个 API
把它放在一起
val renderersFactory = DefaultRenderersFactory(context.applicationContext)
val trackSelector = DefaultTrackSelector()
val loadControl = DefaultLoadControl()
val player = ExoPlayerFactory.newSimpleInstance(context, renderersFactory, trackSelector, loadControl)
player.addListener(this)
// Specify cache folder, my cache folder named media which is inside getCacheDir.
val cacheFolder = File(context.cacheDir, "media")
// Specify cache size and removing policies
val cacheEvictor = LeastRecentlyUsedCacheEvictor(1 * 1024 * 1024) // My cache size will be 1MB and it will automatically remove least recently used files if the size is reached out.
// Build cache
val cache = SimpleCache(cacheFolder, cacheEvictor)
// Build data source factory with cache enabled, if data is available in cache it will return immediately, otherwise it will open a new connection to get the data.
val cacheDataSourceFactory = CacheDataSourceFactory(cache, DefaultHttpDataSourceFactory("ExoplayerDemo"))
val uri = Uri.parse("Put your media url here")
val mediaSource = ExtractorMediaSource.Factory(cacheDataSourceFactory).createMediaSource(uri)
player.prepare(mediaSource)
【讨论】：
val mediaSource = ExtractorMediaSource.Factory(cacheDataSourceFactory).createMediaSource(uri)。你能确认应该是这样吗？
我在这里回答了类似的问题：https://*.com/a/58678192/2029134
基本上，我使用这个库：https://github.com/danikula/AndroidVideoCache 从 URL 缓存文件 然后放到ExoPlayer中。
这里是示例代码：
String mediaURL = "https://my_cool_vid.com/vi.mp4";
SimpleExoPlayer exoPlayer = ExoPlayerFactory.newSimpleInstance(getContext());
HttpProxyCacheServer proxyServer = HttpProxyCacheServer.Builder(getContext()).maxCacheSize(1024 * 1024 * 1024).build();
String proxyURL = proxyServer.getProxyUrl(mediaURL);
DataSource.Factory dataSourceFactory = new DefaultDataSourceFactory(getContext(),
Util.getUserAgent(getContext(), getActivity().getApplicationContext().getPackageName()));
exoPlayer.prepare(new ProgressiveMediaSource.Factory(dataSourceFactory)
.createMediaSource(Uri.parse(proxyURL)););
希望对您有所帮助。
【讨论】：
要解决多个视频或进程尝试访问同一个缓存的问题，您需要一个真正的 Singleton。一种可靠的方法是这样做：
object VideoCache {
private var sDownloadCache: SimpleCache? = null
private const val maxCacheSize: Long = 100 * 1024 * 1024
fun getInstance(context: Context): SimpleCache {
val evictor = LeastRecentlyUsedCacheEvictor(maxCacheSize)
if (sDownloadCache == null) sDownloadCache = SimpleCache(File(context.cacheDir, "koko-media"), evictor)
return sDownloadCache as SimpleCache
}
}
您现在可以使用：
private val simpleCache: SimpleCache by lazy {
VideoCache.getInstance(context)
}
【讨论】：
这里是一个用 OkHttp 替换 demo 数据源的例子，默认是没有缓存 https://github.com/b95505017/ExoPlayer/commit/ebfdda8e7848a2e2e275f5c0525f614b56ef43a6 https://github.com/b95505017/ExoPlayer/tree/okhttp_http_data_source 所以，你只需要正确配置 OkHttp 缓存，请求就会被缓存。
【讨论】：
我已经在渲染器构建器中这样实现了
private static final int BUFFER_SEGMENT_SIZE = 64 * 1024;
private static final int BUFFER_SEGMENT_COUNT = 160;
final String userAgent = Util.getUserAgent(mContext, appName);
final DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
final Allocator allocator = new DefaultAllocator(BUFFER_SEGMENT_SIZE);*
Cache cache = new SimpleCache(context.getCacheDir(), new LeastRecentlyUsedCacheEvictor(1024 * 1024 * 10));
DataSource dataSource = new DefaultUriDataSource(context, bandwidthMeter, userAgent);
CacheDataSource cacheDataSource = new CacheDataSource(cache, dataSource, false, false);
ExtractorSampleSource sampleSource = new ExtractorSampleSource(uri
, cacheDataSource
, allocator
, BUFFER_SEGMENT_COUNT * BUFFER_SEGMENT_SIZE
, new Mp4Extractor());
【讨论】：
除了宝乐的回答，这里准备使用CacheDataSourceFactory的Kotlin版本，保留一个SimpleCache的实例来解决多个Cache对象写入同一个目录的问题。
class CacheDataSourceFactory(private val context: Context,
private val maxCacheSize: Long,
private val maxFileSize: Long) : DataSource.Factory {
private val defaultDatasourceFactory: DefaultDataSourceFactory
private val simpleCache: SimpleCache by lazy {
val evictor = LeastRecentlyUsedCacheEvictor(maxCacheSize)
SimpleCache(File(context.cacheDir, "media"), evictor)
}
init {
val userAgent = Util.getUserAgent(context, context.packageName)
val bandwidthMeter = DefaultBandwidthMeter()
defaultDatasourceFactory = DefaultDataSourceFactory(context,
bandwidthMeter,
DefaultHttpDataSourceFactory(userAgent, bandwidthMeter))
}
override fun createDataSource(): DataSource {
return CacheDataSource(simpleCache,
defaultDatasourceFactory.createDataSource(),
FileDataSource(),
CacheDataSink(simpleCache, maxFileSize),
CacheDataSource.FLAG_BLOCK_ON_CACHE or CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR,
null)
}
}
【讨论】：
这是我在 Kotlin 中的示例（项目可用 here）：
class MainActivity : AppCompatActivity() {
private var player: SimpleExoPlayer? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
if (cache == null) {
cache = SimpleCache(File(cacheDir, "media"), LeastRecentlyUsedCacheEvictor(MAX_PREVIEW_CACHE_SIZE_IN_BYTES))
}
setContentView(R.layout.activity_main)
}
override fun onStart() {
super.onStart()
playVideo()
}
private fun playVideo() {
player = ExoPlayerFactory.newSimpleInstance(this@MainActivity, DefaultTrackSelector())
playerView.player = player
player!!.volume = 1f
player!!.playWhenReady = true
player!!.repeatMode = Player.REPEAT_MODE_ALL
player!!.playVideoFromUrl(this, "https://sample-videos.com/video123/mkv/240/big_buck_bunny_240p_20mb.mkv", cache!!)
// player!!.playVideoFromUrl(this, "https://sample-videos.com/video123/mkv/720/big_buck_bunny_720p_1mb.mkv", cache!!)
// player!!.playVideoFromUrl(this, "https://sample-videos.com/video123/mkv/720/big_buck_bunny_720p_1mb.mkv")
// player!!.playRawVideo(this,R.raw.videoplayback)
}
override fun onStop() {
super.onStop()
playerView.player = null
player!!.release()
player = null
}
companion object {
const val MAX_PREVIEW_CACHE_SIZE_IN_BYTES = 20L * 1024L * 1024L
var cache: com.google.android.exoplayer2.upstream.cache.Cache? = null
@JvmStatic
fun getUserAgent(context: Context): String {
val packageManager = context.packageManager
val info = packageManager.getPackageInfo(context.packageName, 0)
val appName = info.applicationInfo.loadLabel(packageManager).toString()
return Util.getUserAgent(context, appName)
}
}
fun SimpleExoPlayer.playRawVideo(context: Context, @RawRes rawVideoRes: Int) {
val dataSpec = DataSpec(RawResourceDataSource.buildRawResourceUri(rawVideoRes))
val rawResourceDataSource = RawResourceDataSource(context)
rawResourceDataSource.open(dataSpec)
val factory: DataSource.Factory = DataSource.Factory { rawResourceDataSource }
prepare(LoopingMediaSource(ExtractorMediaSource.Factory(factory).createMediaSource(rawResourceDataSource.uri)))
}
fun SimpleExoPlayer.playVideoFromUrl(context: Context, url: String, cache: Cache? = null) = playVideoFromUri(context, Uri.parse(url), cache)
fun SimpleExoPlayer.playVideoFile(context: Context, file: File) = playVideoFromUri(context, Uri.fromFile(file))
fun SimpleExoPlayer.playVideoFromUri(context: Context, uri: Uri, cache: Cache? = null) {
val factory = if (cache != null)
CacheDataSourceFactory(cache, DefaultHttpDataSourceFactory(getUserAgent(context)))
else
DefaultDataSourceFactory(context, MainActivity.getUserAgent(context))
val mediaSource = ExtractorMediaSource.Factory(factory).createMediaSource(uri)
prepare(mediaSource)
}
}
【讨论】：
Exoplayer 的文档列表是class DashDownloader，并有一些用于该类型源的示例代码。 （单击 [Frames] 以返回文档导航。我必须将其删除才能获得深层链接。）
【讨论】：
SimpleCache simpleCache = new SimpleCache(new File(context.getCacheDir(), "media/"+id), evictor);
这里，id 必须是唯一的。
【讨论】：