【重生之我在学Android原生】Media3_androidx.media3.ui.playerview

相关文章

【重生之我在学Android原生】ContentProvider(Java)
【重生之我在学Android原生】Media3

前言

内容颇多，尽量从简

ExoPlayer使用

官方文档
参考文章

实现效果

Android（java）
使用ExoPlayer播放视频，自定义ExoPlayer界面，记录播放位置（横屏竖屏切换/切换至后台等）

案例实现

创建项目

添加依赖

Sync 一下

/// Jetpack Media3 ExoPlayer
    implementation ("androidx.media3:media3-exoplayer:1.3.1")
    implementation ("androidx.media3:media3-ui:1.3.1")
    implementation ("androidx.media3:media3-common:1.3.1")
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转到activity_main.xml

选择Player.View

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.media3.ui.PlayerView
        android:id="@+id/video_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>
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player初始化

要在Activity的生命周期中完成player的初始化销毁等

package com.test.exoplayerexampleapplication;

import androidx.annotation.OptIn;
import androidx.appcompat.app.AppCompatActivity;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.common.util.Util;
import androidx.media3.ui.PlayerView;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

    @OptIn(markerClass = UnstableApi.class) @Override
    protected void onStart() {
        super.onStart();
        if (Util.SDK_INT >= 24) {
            initializePlayer();
        }
    }

    @OptIn(markerClass = UnstableApi.class) @Override
    protected void onResume() {
        super.onResume();
        if (Util.SDK_INT < 24) {
            initializePlayer();
        }
    }

    private void initializePlayer() {}
}
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定义PlayerView，ExoPlayer

    private PlayerView playerView;
    private ExoPlayer exoPlayer;
    private final Uri videoOneUri = Uri.parse("http://www.w3school.com.cn/example/html5/mov_bbb.mp4");
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在AndroidManifest.xml中定义网络权限，如果链接是Http，还需加userCleartextTraffic

<uses-permission android:name="android.permission.INTERNET" />
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android:usesCleartextTraffic="true"
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定义initializePlayer()方法

private void initializePlayer() {
        playerView = findViewById(R.id.video_view);
        exoPlayer = new ExoPlayer.Builder(this).build();
        playerView.setPlayer(exoPlayer);
        MediaItem mediaItem = MediaItem.fromUri(videoOneUri);
        exoPlayer.addMediaItem(mediaItem);
        exoPlayer.prepare();
    }
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运行可以播放视频

释放资源

媒体播放器是很占用资源的，所以当不再需要播放器时，要释放它，当然也要在Activity的生命周期中释放资源

在onStop和onPause适当调用

    @OptIn(markerClass = UnstableApi.class) @Override
    protected void onPause() {
        super.onPause();
        if (Util.SDK_INT < 24) {
            releasePlayer();
        }
    }

    @OptIn(markerClass = UnstableApi.class) @Override
    protected void onStop() {
        super.onStop();
        if (Util.SDK_INT >= 24) {
            releasePlayer();
        }
    }

    private void releasePlayer() {
        exoPlayer.release();
    }
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记录视频的播放状态

重新运行项目，测试切换至后台

切换至后台的生命周期，可以知道当APP放到后台，会调用player.release()方法释放

我们发现视频切换到后台，再切换回来，之前的播放到第四秒，切换回来发现，又回到第0秒。所以，现在需要记录之前播放的位置，播放的状态，播放到第几个视频了。
既然没有onDestory掉Activity
那么定义三个变量(播放位置，播放状态，第几个视频)

    private Long playbackPosition = 0L;
    private int currentMediaItemIndex = 0;
    private boolean playWhenReady = false;
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playbackPosition = exoPlayer.getCurrentPosition();
        currentMediaItemIndex = exoPlayer.getCurrentMediaItemIndex();
        playWhenReady = exoPlayer.getPlayWhenReady();
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exoPlayer.setPlayWhenReady(playWhenReady);
        exoPlayer.seekTo(currentMediaItemIndex, playbackPosition);
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添加新的视频链接

private final Uri videoTwoUri = Uri.parse("https://media.w3.org/2010/05/sintel/trailer.mp4");
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运行测试，播放下一个视频，并播放至一半，切换到后台，再切换回来

横竖屏切换

横竖屏切换的生命周期，Activity被Destory了

使用SharedPreference来存储键值对，参考官方文档，官方推荐用DataStore

那使用DataStore

我们现在做的事情是，使用DataStore Preference来存储视频在释放之前的播放进度，播放状态，播放到第几个视频了。
按照官网配置Preferences DataStore
引入依赖

/// Preferences DataStore
    implementation("androidx.datastore:datastore-preferences:1.0.0")
    /// RxJava2 support
    implementation("androidx.datastore:datastore-preferences-rxjava2:1.0.0")
    /// RxJava3 support
    implementation("androidx.datastore:datastore-preferences-rxjava3:1.0.0")
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实例RxDataStore，销毁

private RxDataStore<Preferences> dataStore;
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if (dataStore == null) {
            dataStore = new RxPreferenceDataStoreBuilder(this, "ExoPlayerKeys").build();
        }
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    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (dataStore != null) {
            dataStore.dispose();
        }
    }
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定义三个Key

    Preferences.Key<Integer> currentMediaItemIndexPK;
    Preferences.Key<Integer> playbackPositionPK;
    Preferences.Key<Boolean> playWhenReadyPK;
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currentMediaItemIndexPK = PreferencesKeys.intKey("currentMediaItemIndex");
        playbackPositionPK = PreferencesKeys.intKey("playbackPosition");
        playWhenReadyPK = PreferencesKeys.booleanKey("playWhenReady");
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使用PreferencesKeys存储值

private void saveVideoRecord() {
        dataStore.updateDataAsync(preferences -> {
            MutablePreferences mutablePreferences = preferences.toMutablePreferences();
            mutablePreferences.set(currentMediaItemIndexPK, currentMediaItemIndex);
            mutablePreferences.set(playbackPositionPK, playbackPosition.intValue());
            mutablePreferences.set(playWhenReadyPK, playWhenReady);
            return Single.just(mutablePreferences);
        });
    }
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在onCreate()中取出之前存储的值，首次运行时，是没有存值的，所以会异常NULL，所以没有值就初始化这些变量

try {
            currentMediaItemIndex = dataStore.data().map(preferences -> preferences.get(currentMediaItemIndexPK)).blockingFirst();
        } catch (Exception e) {
            currentMediaItemIndex = 0;
        }
        try {
            playbackPosition = Long.valueOf(dataStore.data().map(preferences -> preferences.get(playbackPositionPK)).blockingFirst());
        } catch (Exception e) {
            playbackPosition = 0L;
        }
        try {
            playWhenReady = dataStore.data().map(preferences -> preferences.get(playWhenReadyPK)).blockingFirst();
        } catch (Exception e) {
            playWhenReady = false;
        }
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删除APP，重新运行项目，旋转屏幕也能记录播放状态，和播放进度，播放第几个视频


旋转后，仍然从之前播放的进度继续，保持暂停。

监听事件

参考链接

@OptIn(markerClass = UnstableApi.class)
    private void addPlayerListener() {
        listener = new Player.Listener() {
            @OptIn(markerClass = UnstableApi.class)
            @Override
            public void onPlaybackStateChanged(int playbackState) {
                Player.Listener.super.onPlaybackStateChanged(playbackState);
                String stateString = "UNKNOWN_STATE";
                if (playbackState == ExoPlayer.STATE_IDLE) {
                    stateString = "EXoPlayer.STATE_IDLE";
                } else if (playbackState == ExoPlayer.STATE_BUFFERING) {
                    stateString = "ExoPlayer.STATE_BUFFERING";
                } else if (playbackState == Player.STATE_READY) {
                    stateString = "ExoPlayer.STATE_READY";
                } else if (playbackState == Player.STATE_ENDED) {
                    stateString = "ExoPlayer.STATE_ENDED";
                }
                Log.d(TAG, "changed state to " + stateString);
            }
        };
        exoPlayer.addListener(listener);
        analyticsListener = new AnalyticsListener() {
            @Override
            public void onRenderedFirstFrame(EventTime eventTime, Object output, long renderTimeMs) {
                AnalyticsListener.super.onRenderedFirstFrame(eventTime, output, renderTimeMs);
                Log.i(TAG, "AnalyticsListener - onRenderedFirstFrame - 等待多长时间才能在屏幕上看到有意义的内容 - " + renderTimeMs);
            }

            @Override
            public void onDroppedVideoFrames(EventTime eventTime, int droppedFrames, long elapsedMs) {
                AnalyticsListener.super.onDroppedVideoFrames(eventTime, droppedFrames, elapsedMs);
                Log.i(TAG, "AnalyticsListener - onDroppedVideoFrames - 视频丢帧 - " + droppedFrames);
            }

            @Override
            public void onAudioUnderrun(EventTime eventTime, int bufferSize, long bufferSizeMs, long elapsedSinceLastFeedMs) {
                AnalyticsListener.super.onAudioUnderrun(eventTime, bufferSize, bufferSizeMs, elapsedSinceLastFeedMs);
                Log.i(TAG, "AnalyticsListener - onAudioUnderrun - 音频欠载 - " + bufferSizeMs);
            }
        };
        exoPlayer.addAnalyticsListener(analyticsListener);
    }
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自定义ExoPlayer界面

按住Command键，左键查看PlayerView.java,鼠标hover在文件上，看它的位置，可以顺藤摸瓜找到它的源码

布局界面在这里

复制到自己的项目中

在此基础上更改custom_player_control_view.xml

MediaSessionService后台播放

参考文章

实现效果

让媒体挂在后台播放，如下图

正如官网所说，可以用在长视频，听视频。显然上面没有很多的交互，如果短视频用这个，既看不到播放的内容，也没啥交互，就还是不用MediaSession

案例实现

按照官方配置的步骤，语言还是采用Java。将构建一个MediaSession，让他在后台一直播放，同时可以自定义几个按钮，如点赞，收藏。最后监听视频是否播放。

MediaController

显然需要用到MediaSessionService和MediaController

创建项目

按照步骤，先new 一个ListenableFuture controllerFuture
先引入依赖

    implementation ("androidx.media3:media3-session:1.3.1")
    implementation ("androidx.media3:media3-exoplayer:1.3.1")
    implementation ("androidx.media3:media3-ui:1.3.1")
    implementation ("androidx.media3:media3-common:1.3.1")
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定义MediaController

package com.test.mediasessionserviceexample;

import androidx.appcompat.app.AppCompatActivity;
import androidx.media3.common.MediaItem;
import androidx.media3.common.MediaMetadata;
import androidx.media3.session.MediaController;
import androidx.media3.session.SessionToken;

import android.content.ComponentName;
import android.net.Uri;
import android.os.Bundle;

import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.MoreExecutors;

import java.util.concurrent.ExecutionException;

public class MainActivity extends AppCompatActivity {

    ListenableFuture<MediaController> controllerFuture;
    private final String mediaUrl = "https://media.w3.org/2010/05/sintel/trailer.mp4";

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

        SessionToken sessionToken = new SessionToken(this, new ComponentName(this, 你的服务));
        controllerFuture = new MediaController.Builder(this, sessionToken).buildAsync();
        controllerFuture.addListener(() -> {
            Uri uri = Uri.parse(mediaUrl);
            MediaMetadata metadata = new MediaMetadata.Builder()
                    .setArtist("阿笙")
                    .setTitle("我名字是视频")
                    .build();
            MediaItem mediaItem = new MediaItem.Builder()
                    .setMediaId("media-one")
                    .setUri(uri)
                    .setMediaMetadata(metadata).build();
            try {
                MediaController mediaController = controllerFuture.get();
                mediaController.setMediaItem(mediaItem);
                mediaController.prepare();
            } catch (ExecutionException | InterruptedException e) {
                throw new RuntimeException(e);
            }
        }, MoreExecutors.directExecutor());
    }

    @Override
    protected void onStop() {
        super.onStop();
        MediaController.releaseFuture(controllerFuture);
    }
}
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定义服务MediaSessionService

package com.test.mediasessionserviceexample;

import android.content.Intent;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.media3.common.Player;
import androidx.media3.exoplayer.ExoPlayer;
import androidx.media3.session.MediaSession;
import androidx.media3.session.MediaSession.ControllerInfo;
import androidx.media3.session.MediaSessionService;

public class PlaybackService extends MediaSessionService {
    private MediaSession mediaSession = null;

    @Override
    public void onCreate() {
        super.onCreate();
        ExoPlayer player = new ExoPlayer.Builder(this).build();
        mediaSession = new MediaSession.Builder(this, player).build();
    }

    @Nullable
    @Override
    public MediaSession onGetSession(@NonNull ControllerInfo controllerInfo) {
        return mediaSession;
    }

    @Override
    public void onTaskRemoved(Intent rootIntent) {
        super.onTaskRemoved(rootIntent);
        Player player = mediaSession.getPlayer();
        if (!player.getPlayWhenReady() || player.getMediaItemCount() == 0 || player.getPlaybackState() == Player.STATE_ENDED) {
            stopSelf();
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mediaSession.getPlayer().release();
        mediaSession.release();
        mediaSession = null;
    }
}
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注册服务/申明服务

<service android:name=".PlaybackService"
            android:foregroundServiceType="mediaPlayback"
            android:exported="true">
            <intent-filter>
                <action android:name="androidx.media3.session.MediaSessionService"/>
            </intent-filter>
        </service>
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申明权限（网络、前台服务）

<uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_MEDIA_PLAYBACK" />
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运行项目

下拉通知，可以看到这个服务，

定义按钮CommandButton

引入图标

    private CommandButton cBRemoveFromLikes;
    private CommandButton cBRemoveFromFavorites;
    private CommandButton cBAddToLikes;
    private CommandButton cBAddToFavorites;
    private SessionCommand sCAddToLikes;
    private SessionCommand sCAddToFavorites;
    private SessionCommand sCRemoveFromLike;
    private SessionCommand sCRemoveFromFavorite;
    private static final String SAVE_TO_LIKES = "save to likes";
    private static final String SAVE_TO_FAVORITES = "save to favorites";
    private static final String REMOVE_FROM_LIKES = "remove from likes";
    private static final String REMOVE_FROM_FAVORITES = "remove from favorites";
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sCAddToLikes = new SessionCommand(SAVE_TO_LIKES, new Bundle());
        sCAddToFavorites = new SessionCommand(SAVE_TO_FAVORITES, new Bundle());
        sCRemoveFromLike = new SessionCommand(REMOVE_FROM_LIKES, new Bundle());
        sCRemoveFromFavorite = new SessionCommand(REMOVE_FROM_FAVORITES, new Bundle());
        cBAddToLikes = buildCommandButton(SAVE_TO_LIKES, R.drawable.like_icon, sCAddToLikes);
        cBAddToFavorites = buildCommandButton(SAVE_TO_FAVORITES, R.drawable.favorite_icon, sCAddToFavorites);
        cBRemoveFromLikes = buildCommandButton(REMOVE_FROM_LIKES, R.drawable.like_remove_icon, sCRemoveFromLike);
        cBRemoveFromFavorites = buildCommandButton(REMOVE_FROM_FAVORITES, R.drawable.favorite_remove_icon, sCRemoveFromFavorite);
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private CommandButton buildCommandButton(String displayName, int iconResId, SessionCommand sessionCommand) {
        return new CommandButton.Builder()
                .setDisplayName(displayName)
                .setIconResId(iconResId)
                .setSessionCommand(sessionCommand)
                .build();
    }
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自定义MediaSession的布局

定义MediaSession可以使用哪些自定义命令
在MediaSession.Builder()中setCallback 回调，setCustomLayout布局

通过接收customAction的值，判断当前是什么命令，对应设置布局

class CustomMediaSessionCallback implements MediaSession.Callback {
        @OptIn(markerClass = UnstableApi.class)
        @NonNull
        @Override
        public ConnectionResult onConnect(@NonNull MediaSession session, @NonNull ControllerInfo controller) {
            SessionCommands sessionCommands = ConnectionResult.DEFAULT_SESSION_COMMANDS.buildUpon()
                    .add(sCAddToLikes)
                    .add(sCAddToFavorites)
                    .add(sCRemoveFromLike)
                    .add(sCRemoveFromFavorite)
                    .build();

            return new ConnectionResult.AcceptedResultBuilder(session)
                    .setAvailableSessionCommands(sessionCommands)
                    .build();
        }

        @OptIn(markerClass = UnstableApi.class)
        @NonNull
        @Override
        public ListenableFuture<SessionResult> onCustomCommand(@NonNull MediaSession session, @NonNull ControllerInfo controller, @NonNull SessionCommand customCommand, @NonNull Bundle args) {
            final CommandButton buttonOne = mediaSession.getCustomLayout().get(0);
            final CommandButton buttonTwo = mediaSession.getCustomLayout().get(1);
            switch (customCommand.customAction) {
                case SAVE_TO_LIKES:
                    mediaSession.setCustomLayout(ImmutableList.of(cBRemoveFromLikes, buttonTwo));
                    break;
                case SAVE_TO_FAVORITES:
                    mediaSession.setCustomLayout(ImmutableList.of(buttonOne, cBRemoveFromFavorites));
                    break;
                case REMOVE_FROM_LIKES:
                    mediaSession.setCustomLayout(ImmutableList.of(cBAddToLikes, buttonTwo));
                    break;
                case REMOVE_FROM_FAVORITES:
                    mediaSession.setCustomLayout(ImmutableList.of(buttonOne, cBAddToFavorites));
                    break;
                default:
                    throw new RuntimeException("not implement");
            }
            return Futures.immediateFuture(new SessionResult(SessionResult.RESULT_SUCCESS));
        }
    }
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运行测试

自定义Player的行为(play等)

        ExoPlayer player = new ExoPlayer.Builder(this).build();

        ForwardingPlayer forwardingPlayer = new ForwardingPlayer(player) {
            @Override
            public void play() {
                super.play();
                Log.d("ForwardingPlayer Log", "play!");
            }
        };

        mediaSession = new MediaSession.Builder(this, forwardingPlayer)
                .setCallback(new CustomMediaSessionCallback())
                .setCustomLayout(ImmutableList.of(cBAddToLikes, cBAddToFavorites))
                .build();
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MediaLibraryService

实现目标

参考文档
主要实现三个函数

• onGetLibraryRoot()
• onGetChildren()
• onGetSearchResult()
  

实现效果

创建一个目录，目录下有三个文件，并且可以根据标题搜索这三个文件

案例实现

采用JAVA实现

创建项目接着引入依赖

    implementation ("androidx.media3:media3-session:1.3.1")
    implementation ("androidx.media3:media3-exoplayer:1.3.1")
    implementation ("androidx.media3:media3-ui:1.3.1")
    implementation ("androidx.media3:media3-common:1.3.1")
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初始化MediaLibraryService

和MediaSession操作差不多，先实例

package com.test.medialibraryservicetestapplication;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.media3.common.MediaItem;
import androidx.media3.exoplayer.ExoPlayer;
import androidx.media3.session.LibraryResult;
import androidx.media3.session.MediaLibraryService;
import androidx.media3.session.MediaSession;

import com.google.common.collect.ImmutableList;
import com.google.common.util.concurrent.ListenableFuture;

public class PlaybackService extends MediaLibraryService {
    MediaLibrarySession mediaLibrarySession = null;
    MediaLibrarySession.Callback callback = new MediaLibrarySession.Callback() {
        @NonNull
        @Override
        public ListenableFuture<LibraryResult<MediaItem>> onGetLibraryRoot(@NonNull MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @Nullable MediaLibraryService.LibraryParams params) {
            return MediaLibrarySession.Callback.super.onGetLibraryRoot(session, browser, params);
        }

        @NonNull
        @Override
        public ListenableFuture<LibraryResult<ImmutableList<MediaItem>>> onGetChildren(MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @NonNull String parentId, int page, int pageSize, @Nullable MediaLibraryService.LibraryParams params) {
            return MediaLibrarySession.Callback.super.onGetChildren(session, browser, parentId, page, pageSize, params);
        }

        @NonNull
        @Override
        public ListenableFuture<LibraryResult<ImmutableList<MediaItem>>> onGetSearchResult(@NonNull MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @NonNull String query, int page, int pageSize, @Nullable MediaLibraryService.LibraryParams params) {
            return MediaLibrarySession.Callback.super.onGetSearchResult(session, browser, query, page, pageSize, params);
        }
    };

    @Nullable
    @Override
    public MediaLibrarySession onGetSession(@NonNull MediaSession.ControllerInfo controllerInfo) {
        return mediaLibrarySession;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        ExoPlayer player = new ExoPlayer.Builder(this).build();
        mediaLibrarySession = new MediaLibraryService.MediaLibrarySession.Builder(this, player, callback).build();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mediaLibrarySession != null) {
            mediaLibrarySession.getPlayer().release();
            mediaLibrarySession.release();
            mediaLibrarySession = null;
        }
    }
}
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创建树形结构存储数据

要获取根对象，需要有一个建好的树形数据，就如下面这幅图上，它是一个树，树的根节点RootNode，分叉出去好几个类目，简单起见，这里先弄简单的Root->Music/Game/Study

定义树

构建根节点，添加三个子节点到根节点

最后改为单例

package com.test.medialibraryservicetestapplication;

import java.util.HashMap;
import java.util.Map;

public class Tree {
    Map<String, TreeNode> treeNodes;
    final String ROOT_ID = "root";
    final String MUSIC_ID = "music";
    final String GAME_ID = "game";
    final String STUDY_ID = "study";
    final String ROOT_TITLE = "root title";
    final String MUSIC_TITLE = "music title";
    final String GAME_TITLE = "game title";
    final String STUDY_TITLE = "study title";
    private final static Tree instance = new Tree();

    public static Tree genInstance() {
        return instance;
    }
    private boolean isInitialized = false;
    private Tree() {
        if (!isInitialized) {
            isInitialized = true;
            treeNodes = new HashMap<>();
            TreeNode rootNode = new TreeNode(ROOT_ID, ROOT_TITLE);
            TreeNode musicNode = new TreeNode(MUSIC_ID, MUSIC_TITLE);
            TreeNode gameNode = new TreeNode(GAME_ID, GAME_TITLE);
            TreeNode studyNode = new TreeNode(STUDY_ID, STUDY_TITLE);
            rootNode.children.add(musicNode.node);
            rootNode.children.add(gameNode.node);
            rootNode.children.add(studyNode.node);
            treeNodes.put(ROOT_ID, rootNode);
        }

    }
}
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获取根节点

MediaItem getTreeRoot() {
        return Objects.requireNonNull(treeNodes.get(ROOT_ID)).node;
    }
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        @NonNull
        @Override
        public ListenableFuture<LibraryResult<MediaItem>> onGetLibraryRoot(@NonNull MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @Nullable MediaLibraryService.LibraryParams params) {
            return Futures.immediateFuture(LibraryResult.ofItem(Tree.genInstance().getTreeRoot(), params));
        }
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获取结点的子节点集合

    List<MediaItem> getNodeChildren(String treeNodeId) {
        return Objects.requireNonNull(treeNodes.get(treeNodeId)).children;
    }
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@NonNull
        @Override
        public ListenableFuture<LibraryResult<ImmutableList<MediaItem>>> onGetChildren(MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @NonNull String parentId, int page, int pageSize, @Nullable MediaLibraryService.LibraryParams params) {
            List<MediaItem> children = Tree.genInstance().getNodeChildren(parentId);
            if (!children.isEmpty()) {
                return Futures.immediateFuture(LibraryResult.ofItemList(children, params));
            }
            return Futures.immediateFuture(LibraryResult.ofError(LibraryResult.RESULT_ERROR_BAD_VALUE));
        }
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注册Service及申明权限

<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_MEDIA_PLAYBACK" />
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<service
            android:name=".PlaybackService"
            android:exported="true"
            android:foregroundServiceType="mediaPlayback">
            <intent-filter>
                <action android:name="androidx.media3.session.MediaSessionService" />
            </intent-filter>
        </service>
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MediaBrowser浏览MediaLibraryService定义的媒体库

获取MediaLibraryService构建的媒体库的根节点

获取某一节点下的子节点

运行测试

运行项目，并在60行打上断点，看到value属性值为三个MediaItem对象
可以看到获取到根节点下的三个子节点

package com.test.medialibraryservicetestapplication;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.media3.common.MediaItem;
import androidx.media3.exoplayer.ExoPlayer;
import androidx.media3.session.LibraryResult;
import androidx.media3.session.MediaLibraryService;
import androidx.media3.session.MediaSession;

import com.google.common.collect.ImmutableList;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;

import java.util.List;

public class PlaybackService extends MediaLibraryService {
    MediaLibrarySession mediaLibrarySession = null;
    MediaLibrarySession.Callback callback = new MediaLibrarySession.Callback() {
        @NonNull
        @Override
        public ListenableFuture<LibraryResult<MediaItem>> onGetLibraryRoot(@NonNull MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @Nullable MediaLibraryService.LibraryParams params) {
            return Futures.immediateFuture(LibraryResult.ofItem(Tree.genInstance().getTreeRoot(), params));
        }

        @NonNull
        @Override
        public ListenableFuture<LibraryResult<ImmutableList<MediaItem>>> onGetChildren(MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @NonNull String parentId, int page, int pageSize, @Nullable MediaLibraryService.LibraryParams params) {
            List<MediaItem> children = Tree.genInstance().getNodeChildren(parentId);
            if (!children.isEmpty()) {
                return Futures.immediateFuture(LibraryResult.ofItemList(children, params));
            }
            return Futures.immediateFuture(LibraryResult.ofError(LibraryResult.RESULT_ERROR_BAD_VALUE));
        }

        @NonNull
        @Override
        public ListenableFuture<LibraryResult<ImmutableList<MediaItem>>> onGetSearchResult(@NonNull MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @NonNull String query, int page, int pageSize, @Nullable MediaLibraryService.LibraryParams params) {
            return MediaLibrarySession.Callback.super.onGetSearchResult(session, browser, query, page, pageSize, params);
        }
    };

    @Nullable
    @Override
    public MediaLibrarySession onGetSession(@NonNull MediaSession.ControllerInfo controllerInfo) {
        return mediaLibrarySession;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        ExoPlayer player = new ExoPlayer.Builder(this).build();
        mediaLibrarySession = new MediaLibraryService.MediaLibrarySession.Builder(this, player, callback).build();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mediaLibrarySession != null) {
            mediaLibrarySession.getPlayer().release();
            mediaLibrarySession.release();
            mediaLibrarySession = null;
        }
    }
}
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搜索媒体库

首先还是去Tree中定义搜索的函数

    List<MediaItem> search(String query) {
        List<MediaItem> titleMatches = new ArrayList<>();
        Object[] words = Arrays.stream(query.split(" ")).map(it -> it.trim().toLowerCase()).filter(it -> it.length() > 1).toArray();
        titleNodes.keySet().forEach(title -> {
            TreeNode treeNode = titleNodes.get(title);
            for (Object word : words) {
                boolean contains = title.contains((CharSequence) word);
                if (contains) {
                    assert treeNode != null;
                    titleMatches.add(treeNode.node);
                }
            }
        });
        return titleMatches;
    }
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    public static Map<String, TreeNode> titleNodes;
titleNodes = new HashMap<>();
            titleNodes.put(MUSIC_TITLE, musicNode);
            titleNodes.put(GAME_TITLE, gameNode);
            titleNodes.put(STUDY_TITLE, studyNode);
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        @NonNull
        @Override
        public ListenableFuture<LibraryResult<ImmutableList<MediaItem>>> onGetSearchResult(@NonNull MediaLibrarySession session, @NonNull MediaSession.ControllerInfo browser, @NonNull String query, int page, int pageSize, @Nullable MediaLibraryService.LibraryParams params) {
            return Futures.immediateFuture(LibraryResult.ofItemList(Tree.genInstance().search(query), params));
        }
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MediaBrowser 搜索

    private void searchMedia(String query) {
        ListenableFuture<LibraryResult<ImmutableList<MediaItem>>> searchFuture = mediaBrowser.getSearchResult(query, 0, Integer.MAX_VALUE, null);
        searchFuture.addListener(() -> {
            try {
                LibraryResult<ImmutableList<MediaItem>> immutableListLibraryResult = searchFuture.get();
                ImmutableList<MediaItem> value = immutableListLibraryResult.value;
            } catch (ExecutionException | InterruptedException e) {
                throw new RuntimeException(e);
            }
        }, MoreExecutors.directExecutor());
    }
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搜索“ga”，可以查到“game”这个MediaItem

填坑中…

内容是真的多!