IjkMediaPlayer.setDataSource播放raw文件夹内文件

你可以使用以下代码来使用IjkMediaPlayer播放raw文件夹内的文件：

import android.content.res.AssetFileDescriptor;
import android.content.res.Resources;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;

import java.io.IOException;

import tv.danmaku.ijk.media.player.IjkMediaPlayer;

public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback, MediaPlayer.OnPreparedListener {

    private SurfaceView mSurfaceView;
    private IjkMediaPlayer mMediaPlayer;
    private SurfaceHolder mSurfaceHolder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 初始化IjkMediaPlayer
        IjkMediaPlayer.loadLibrariesOnce(null);
        IjkMediaPlayer.native_profileBegin("libijkplayer.so");

        mSurfaceView = findViewById(R.id.surface_view);
        mSurfaceHolder = mSurfaceView.getHolder();
        mSurfaceHolder.addCallback(this);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // 设置MediaPlayer
        mMediaPlayer = new IjkMediaPlayer();
        mMediaPlayer.setDisplay(mSurfaceHolder);

        // 获取音频焦点
        AudioManager audioManager = (AudioManager) getSystemService(AUDIO_SERVICE);
        audioManager.requestAudioFocus(null, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);

        // 播放raw文件夹内的文件
        Resources resources = getResources();
        AssetFileDescriptor afd = resources.openRawResourceFd(R.raw.test);
        try {
            mMediaPlayer.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 准备播放
        mMediaPlayer.setOnPreparedListener(this);
        mMediaPlayer.prepareAsync();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // 释放MediaPlayer
        mMediaPlayer.release();
        mMediaPlayer = null;
    }

    @Override
    public void onPrepared(MediaPlayer mp) {
        // 开始播放
        mMediaPlayer.start();
    }
}

注意，这里使用了IjkMediaPlayer而不是Android自带的MediaPlayer，因为IjkMediaPlayer支持更多的视频格式，并且在播放过程中能够实时调整画面大小和速度等参数。同时，需要在项目的build.gradle文件中添加以下依赖：

dependencies {
    implementation 'tv.danmaku.ijk.media:ijkplayer-java:0.8.8'
    implementation 'tv.danmaku.ijk.media:ijkplayer-armv7a:0.8.8'
}