前言
本文介紹如何通過系統MediaPlayer
,IjkPlayer
,ExoPlayer
分別播放安卓項目下的Raw或Assets文件夾中的音視頻文件。
在某些情況下,我們會把一些音視頻文件,如Mp3,Mp4等,直接放在安裝包中的Raw或者Assets文件夾裏,這些音視頻文件可能作爲特定場景的提示音,或者視頻片頭等等。關於Raw和Assets資源文件,這裏不作過多討論,總的來講,他們都是被打包進APK中的文件,不會被編譯成二進制,程序可以直接訪問,無需額外的權限。
先說明一下本文代碼的構建環境和使用的播放內核版本:
- Java 1.7
- Android Studio 3.1.2
- Gradle 4.4
- IjkPlayer 0.8.8
- ExoPlayer 2.8.3
效果演示
Raw/Assets資源文件訪問方式
在項目文件夾中的位置:
Raw文件訪問方式
Raw
文件位於res/raw目錄下,Raw文件會被映射到R.java文件中,所以訪問的時候直接使用資源ID即可,如
R.raw.raw_video
或者獲得該文件的AssetFileDescriptor:
AssetFileDescriptor afd = getResources().openRawResourceFd(R.raw.raw_video);
Assets文件訪問方式
Assets
文件夾下的文件不會被映射到R.java中,訪問的時候需要AssetManager類。
AssetManager am = getAssets();
try {
AssetFileDescriptor afd= am.openFd(fileName);
} catch (IOException e) {
e.printStackTrace();
}
AssetFileDescriptor可以理解成訪問Raw/Assets文件的一個入口,或者說是一把鑰匙。
Raw/Assets文件還有其他的訪問方式,比如通過ContentResolver
,又或者直接開啓一個InputStream去讀取文件,這應該是播放器內核需要做的事情,我們只需要給播放器提供以上的信息即可。
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下面直接上代碼
通過系統MediaPlayer播放音視頻
- Raw文件
//實例化播放內核
android.media.MediaPlayer mediaPlayer = new android.media.MediaPlayer();
//獲得播放源訪問入口
AssetFileDescriptor afd = getResources().openRawResourceFd(R.raw.raw_video); // 注意這裏的區別
//給MediaPlayer設置播放源
mediaPlayer.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
//設置準備就緒狀態監聽
mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
// 開始播放
mediaPlayer.start();
}
});
//準備播放
mediaPlayer.prepareAsync();
- Assets 文件
//實例化播放內核
android.media.MediaPlayer mediaPlayer = new android.media.MediaPlayer();
//獲得播放源訪問入口
AssetManager am = getAssets();
try {
AssetFileDescriptor afd = am.openFd("assets_video.mp4");// 注意這裏的區別
//給MediaPlayer設置播放源
mediaPlayer.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
} catch (IOException e) {
e.printStackTrace();
}
//設置準備就緒狀態監聽
mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
// 開始播放
mediaPlayer.start();
}
});
//準備播放
mediaPlayer.prepareAsync();
代碼中每一步都有註釋,可以說非常詳細了。簡單總結一下,無論播放Raw文件還是Assets文件,我們首先獲得AssetFileDescriptor,然後設置給MediaPlayer。
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通過IjkPlayer播放音視頻
- Raw 文件
//實例化播放內核
tv.danmaku.ijk.media.player.IjkMediaPlayer ijkPlayer = new tv.danmaku.ijk.media.player.IjkMediaPlayer();
//獲得播放源訪問入口
AssetFileDescriptor afd = getResources().openRawResourceFd(R.raw.raw_video); // 注意這裏的區別
//構建IjkPlayer能識別的IMediaDataSource,下面的RawDataSourceProvider實現了IMediaDataSource接口
RawDataSourceProvider sourceProvider = new RawDataSourceProvider(fd);
//給IjkPlayer設置播放源
ijkPlayer.setDataSource(sourceProvider);
//設置準備就緒狀態監聽
ijkPlayer .setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
// 開始播放
ijkPlayer.start();
}
});
//準備播放
ijkPlayer.prepareAsync();
- Assets 文件
//實例化播放內核
tv.danmaku.ijk.media.player.IjkMediaPlayer ijkPlayer = new tv.danmaku.ijk.media.player.IjkMediaPlayer();
//獲得播放源訪問入口
AssetManager am = getAssets();
try {
AssetFileDescriptor afd = am.openFd("assets_video.mp4");// 注意這裏的區別
//構建IjkPlayer能識別的IMediaDataSource,下面的RawDataSourceProvider實現了IMediaDataSource接口
RawDataSourceProvider sourceProvider = new RawDataSourceProvider(fd);
//給IjkPlayer設置播放源
ijkPlayer.setDataSource(sourceProvider);
} catch (IOException e) {
e.printStackTrace();
}
//設置準備就緒狀態監聽
ijkPlayer .setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mp) {
// 開始播放
ijkPlayer.start();
}
});
//準備播放
ijkPlayer.prepareAsync();
補充下,其中的
RawDataSourceProvider
實現了IMediaDataSource
接口,IMediaDataSource
是IjkPlayer
包中的接口,實現了IMediaDataSource
接口的類可以設置給IjkPlayer作爲播放源。就像下面這樣:
import tv.danmaku.ijk.media.player.misc.IMediaDataSource;
public class RawDataSourceProvider implements IMediaDataSource {
private AssetFileDescriptor mDescriptor;
private byte[] mMediaBytes;
public RawDataSourceProvider(AssetFileDescriptor descriptor) {
this.mDescriptor = descriptor;
}
@Override
public int readAt(long position, byte[] buffer, int offset, int size) {
if (position + 1 >= mMediaBytes.length) {
return -1;
}
int length;
if (position + size < mMediaBytes.length) {
length = size;
} else {
length = (int) (mMediaBytes.length - position);
if (length > buffer.length)
length = buffer.length;
length--;
}
// 把文件內容copy到buffer中;
System.arraycopy(mMediaBytes, (int) position, buffer, offset, length);
return length;
}
@Override
public long getSize() throws IOException {
long length = mDescriptor.getLength();
if (mMediaBytes == null) {
InputStream inputStream = mDescriptor.createInputStream();
mMediaBytes = readBytes(inputStream);
}
return length;
}
@Override
public void close() throws IOException {
if (mDescriptor != null)
mDescriptor.close();
mDescriptor = null;
mMediaBytes = null;
}
//讀取文件內容
private byte[] readBytes(InputStream inputStream) throws IOException {
ByteArrayOutputStream byteBuffer = new ByteArrayOutputStream();
int bufferSize = 1024;
byte[] buffer = new byte[bufferSize];
int len;
while ((len = inputStream.read(buffer)) != -1) {
byteBuffer.write(buffer, 0, len);
}
return byteBuffer.toByteArray();
}
}
小結一下,我們首先獲取到Raw/Assets文件的
AssetFileDescriptor
,然後用它去構建一個IMediaDataSource
,最後設置給IjkPlayer
。
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通過ExoPlayer播放音視頻
- ExoPlayer播放器內核的實例化有點複雜,這裏單獨寫
//實例化播放內核
TrackSelection.Factory videoTrackSelectionFactory =
new AdaptiveTrackSelection.Factory(new DefaultBandwidthMeter());
DefaultTrackSelector mTrackSelector = new DefaultTrackSelector(videoTrackSelectionFactory);
boolean preferExtensionDecoders = true;
boolean useExtensionRenderers = true;//是否開啓擴展
@DefaultRenderersFactory.ExtensionRendererMode int extensionRendererMode = useExtensionRenderers
? (preferExtensionDecoders ? DefaultRenderersFactory.EXTENSION_RENDERER_MODE_PREFER
: DefaultRenderersFactory.EXTENSION_RENDERER_MODE_ON)
: DefaultRenderersFactory.EXTENSION_RENDERER_MODE_OFF;
DefaultRenderersFactory rendererFactory = new DefaultRenderersFactory(mAppContext, extensionRendererMode);
DefaultLoadControl loadControl = new DefaultLoadControl();
//工廠方法獲得播放器實例
om.google.android.exoplayer2.SimpleExoPlayer exoPlayer =
ExoPlayerFactory.newSimpleInstance(rendererFactory, mTrackSelector, loadControl, null);
- Raw 文件
//構建Raw文件播放源--RawResourceDataSource
DataSpec dataSpec = new DataSpec(RawResourceDataSource.buildRawResourceUri(R.raw.raw_video));
RawResourceDataSource rawResourceDataSource = new RawResourceDataSource(this);
try {
rawResourceDataSource.open(dataSpec);
} catch (RawResourceDataSource.RawResourceDataSourceException e) {
e.printStackTrace();
}
//構建ExoPlayer能識別的播放源--MediaSource
String url = rawDataSource.getUri().toString();
MediaSource mediaSource = ExoSourceManager.newInstance(mAppContext, getHeaders()).getMediaSource(
url, false, false, MediaPlayerManager.instance().isLooping(), null
);
//給ExoPlayer設置播放源,並準備播放
exoPlayer.prepare(mediaSource);
//讓ExoPlayer準備好後就開始播放
exoPlayer.setPlayWhenReady(true);
- Assets 文件
//構建ExoPlayer能識別的播放源--MediaSource
String url = "file:///android_asset/" + "assets_video.mp4";
MediaSource mediaSource = ExoSourceManager.newInstance(mAppContext, getHeaders()).getMediaSource(
url, false, false, MediaPlayerManager.instance().isLooping(), null
);
//給ExoPlayer設置播放源,並準備播放
exoPlayer.prepare(mediaSource);
//讓ExoPlayer準備好後就開始播放
exoPlayer.setPlayWhenReady(true);
小結:ExoPlayer實例化的時候複雜一點,需要按照官方文檔一步步來。播放Raw文件的時候,需要先構建出
RawResourceDataSource
,這是ExoPlayer爲了播放Raw音視頻文件提供的類,然後獲取其中的Uri構建MediaSource
,最後設置給ExoPlayer。播放Assets文件就更簡單了,形如String url = "file:///android_asset/" + "filename"
的Assets文件播放地址可以直接用來構建MediaSource
。
項目地址:https://github.com/maiwenchang/ArtPlayer 歡迎各位Star~~