深入解读.NET MAUI音乐播放器项目（二）：播放内核

播放控制服务

IMusicControlService:
播放控制类，用于当前平台播放器对象的操作，对当前所播放曲目的暂停/播放，下一首/上一首，快进快退（寻迹），随机、单曲模式等功能的控制。

播放控制类包含一个平台特定的播放器，由于要制作通用的播放控制类，IMusicControlService不开放播放器对象的公共访问，而是通过暴露方法操作播放器对象。

在跨平台中的实现：

• Android平台使用Android.Media.MediaPlayer类
• iOS平台使用AVFoundation.AVAudioPlayer类
• Windows平台使用Windows.Media.Playback.MediaPlayer类

虽然不同平台的播放器类都提供了诸如播放，暂停，寻迹的功能，但不同平台存在着微小差别。
比如停止功能 - Stop：

在iOS中的实现：

public partial void Stop()
{if (!IsInitFinished()) { return; }if (CurrentIosPlayer.Playing){CurrentIosPlayer.Stop();OnPlayStatusChanged?.Invoke(this, false);}
}

在Android中，由于Android.Media.MediaPlayer没有提供Stop方法，所以停止的逻辑用寻迹至0位置暂停实现的

public partial void Stop()
{if (CurrentAndroidPlayer.IsPlaying){CurrentAndroidPlayer.SeekTo(0);CurrentAndroidPlayer.Pause();}
}

又如寻迹功能 - SeekTo
在iOS中的实现，postion参数为曲目开始后的时间值，单位秒。改变播放位置是通过直接赋值AVFoundation.AVAudioPlayer.CurrentTime实现的

public partial void SeekTo(double position){if (!IsInitFinished()) { return; }CurrentIosPlayer.CurrentTime = position;
}

在Android中，Android.Media.MediaPlayer提供了SeekTo方法，传入值是毫秒，因此要做一下转换：

public partial void SeekTo(double position)
{CurrentAndroidPlayer.SeekTo((int)position * 1000);}

在传统播放器随机播放时，如果下一曲不是我想听的，我仍然想听上一曲，由于上一曲按钮是随机触发的时机，你可能找不到它了，不得不再音乐列表再搜索它。这可能是个遗憾

我在这个随机模型中引入随机播放映射表，使得在随机模式中，上一曲/下一曲仍然能发挥其作用。

刷新随机列表：
increment为跳转步数，例如increment = 1时相当于下一曲，increment = -1 时相当于上一曲：

private partial int GetShuffleMusicIndex(int originItem, int increment)
{var originItemIndex = 0;foreach (var item in ShuffleMap){if (originItem == item){break;}originItemIndex++;}var newItemIndex = originItemIndex + increment;if (newItemIndex < 0){newItemIndex = LastIndex;}if (newItemIndex > LastIndex){newItemIndex = 0;}var shuffleMapCount = shuffleMap.Count();var musicInfosCount = MusicInfos.Count();if (shuffleMapCount != musicInfosCount){shuffleMap = CommonHelper.GetRandomArry(0, LastIndex);shuffleMapCount = shuffleMap.Count();}if (shuffleMapCount > 0 && newItemIndex < shuffleMapCount){var resultContent = ShuffleMap[newItemIndex];return resultContent;}else{return -1;}
}

GetRandomArry 方法将产生一个指定最小值到最大值连续数列的随机数组

public static int[] GetRandomArry(int minval, int maxval)
{int[] arr = new int[maxval - minval + 1];int i;//初始化数组for (i = 0; i <= maxval - minval; i++){arr[i] = i + minval;}//随机数Random r = new Random();for (int j = maxval - minval; j >= 1; j--){int address = r.Next(0, j);int tmp = arr[address];arr[address] = arr[j];arr[j] = tmp;}//输出foreach (int k in arr){Debug.WriteLine(k + " ");}return arr;
}

关键属性：

• ShuffleMap - 随机播放映射表
• MusicInfos - 播放器音频列表
• LastIndex - 当前播放曲目位于器音频列表位置角标

关键方法：

• Play - 播放
• PauseOrResume - 暂停/恢复
• RebuildMusicInfos - 从播放列队中读取音频列表，刷新播放器队列
• SeekTo - 快进快退（寻迹）
• GetNextMusic - 获取下一首曲目信息
• GetPreMusic - 获取上一首曲目信息
• InitPlayer - 初始化播放器
• UpdateShuffleMap - 更新随机播放映射表
• SetRepeatOneStatus - 设置是否单曲循环
• Duration - 获取当前曲目时长
• CurrentTime - 获取当前曲目播放进度
• IsPlaying - 获取是否在播放中
• IsInitFinished - 获取是否完成播放器初始化

关键事件：

• OnPlayFinished - 完成当前曲目播放时触发
• OnRebuildMusicInfosFinished - 完成刷新播放器队列触发
• OnProgressChanged - 播放进度更改时触发
• OnPlayStatusChanged - 播放状态变更时触发

接口定义：

public interface IMusicControlService
{event EventHandler<bool> OnPlayFinished;event EventHandler OnRebuildMusicInfosFinished;event EventHandler<double> OnProgressChanged;event EventHandler<bool> OnPlayStatusChanged;public IMusicInfoManager MusicInfoManager { get; set; }int[] ShuffleMap { get; }List<MusicInfo> MusicInfos { get; }int LastIndex { get; }Task RebuildMusicInfos(Action callback);void SeekTo(double position);MusicInfo GetNextMusic(MusicInfo current, bool isShuffle);MusicInfo GetPreMusic(MusicInfo current, bool isShuffle);int GetMusicIndex(MusicInfo musicInfo);MusicInfo GetMusicByIndex(int index);Task InitPlayer(MusicInfo musicInfo);void Play(MusicInfo currentMusic);void Stop();void PauseOrResume();void PauseOrResume(bool status);Task UpdateShuffleMap();void SetRepeatOneStatus(bool isRepeatOne);double Duration();double CurrentTime();bool IsPlaying();bool IsInitFinished();
}

曲目管理器设计

IMusicInfoManager:
曲目管理类，用于歌曲队列，歌单的编辑；各曲目集合增加，删除等功能

歌曲队列，歌单等信息存在于本地数据库，曲目管理类将对这些数据增、删、查、改的操作，Abp框架实现的仓储模式为我们生成了Repository对象。

在MusicInfoManager构造函数中注入各仓储依赖

public MusicInfoManager(IRepository<Queue, long> queueRepository,IRepository<PlaylistItem, long> playlistItemRepository,IRepository<Playlist, long> playlistRepository,IUnitOfWorkManager unitOfWorkManager)
{...
}

读取播放队列

播放队列具有一定的代表性，歌单的逻辑与播放队列类似，所以本篇博文着重讲述播放队列的业务

播放队列存在于本地数据库的Queue表中，全部将他们读取。

播放队列的Entry项和设备中的媒体条目是一种弱关联，需要将他们“螯合”起来，连表左联查询后取得MusicInfo集合。

[UnitOfWork]
public async Task<List<MusicInfo>> GetQueueEntry()
{var queueEntrys = await queueRepository.GetAll().ToListAsync();if (_musicInfos == null || _musicInfos.Count == 0){var isSucc = await GetMusicInfos();if (!isSucc.IsSucess){//CommonHelper.ShowNoAuthorized();}_musicInfos = isSucc.Result;}var result =from queue in queueEntrysjoin musicInfo in _musicInfoson queue.MusicInfoId equals musicInfo.Idorderby queue.Rankselect musicInfo;return result.ToList();
}

返回时依据Rank字段递增排序。

添加播放队列

播放整个专辑时，将整个专辑中的所有曲目添加到播放队列：

QueueAllAction在点击播放专辑时触发，首先清空当前播放队列，接着将当前页面绑定的曲目集合（Musics对象）插入到播放队列

private async void QueueAllAction(object obj)
{await MusicInfoManager.ClearQueue();var result = await MusicInfoManager.CreateQueueEntrys(Musics);..
}

MusicInfoManager.cs 中定义了清空播放队列ClearQueue，和歌单中创建曲目集合方法CreateQueueEntrys：

[UnitOfWork]
public async Task ClearQueue()
{await queueRepository.DeleteAsync(c => true);}

[UnitOfWork]
public async Task<bool> CreateQueueEntrys(List<MusicInfo> musicInfos)
{var lastItemRank = queueRepository.GetAll().OrderBy(c => c.Rank).Select(c => c.Rank).LastOrDefault();var entrys = new List<Queue>();foreach (var music in musicInfos){var entry = new Queue(music.Title, lastItemRank, music.Id);lastItemRank++;entrys.Add(entry);}await queueRepository.GetDbContext().AddRangeAsync(entrys);return true;
}

需要注意的是，Rank字段将在队列最后一条后继续递增

曲目排序

曲目排序，原理是通过交换位置实现的，iOS和Android平台都有自己的可排序列表控件，在对选中的条目进行排序（往往是提起条目-拖拽-释放）的过程中，触发事件往往提供当前条目oldMusicInfo，和排斥条目newMusicInfo，调用ReorderQueue时将这辆个参数传入，将这两个MusicInfo的Rank值交换：

[UnitOfWork]
public void ReorderQueue(MusicInfo oldMusicInfo, MusicInfo newMusicInfo)
{var oldMusic = queueRepository.FirstOrDefault(c => c.MusicTitle==oldMusicInfo.Title);var newMusic = queueRepository.FirstOrDefault(c => c.MusicTitle==newMusicInfo.Title);if (oldMusic ==null || newMusic==null){return;}var oldRank = oldMusic.Rank;oldMusic.Rank=newMusic.Rank;newMusic.Rank=oldRank;queueRepository.Update(oldMusic);queueRepository.Update(newMusic);
}

下一首播放

下一首播放将播放队列中，指定的曲目排在当前播放曲目之后，实现方式是线确保目标曲目存在于播放队列。同样，用到了排序逻辑，再将他的排序（Rank值）与当前播放曲目之后的做交换。

public partial async Task<bool> InsertToEndQueueEntry(MusicInfo musicInfo)
{var result = false;var isSuccessCreate = false;//如果没有则先创建if (!await GetIsQueueContains(musicInfo.Title)){isSuccessCreate = await CreateQueueEntry(musicInfo);await unitOfWorkManager.Current.SaveChangesAsync();}else{isSuccessCreate = true;}//确定包含后与下一曲交换位置if (isSuccessCreate){var current = currentMusic;Queue newMusic = null;var lastItem = await queueRepository.FirstOrDefaultAsync(c => c.MusicTitle==current.Title);if (lastItem!=null){newMusic = await queueRepository.FirstOrDefaultAsync(c => c.Rank==lastItem.Rank+1);}var oldMusic = await queueRepository.FirstOrDefaultAsync(c => c.MusicTitle==musicInfo.Title);if (oldMusic ==null || newMusic==null){return true;}var oldRank = oldMusic.Rank;oldMusic.Rank=newMusic.Rank;newMusic.Rank=oldRank;queueRepository.Update(oldMusic);queueRepository.Update(newMusic);result = true;}else{result = false;}return result;
}

其它关键方法：

• ClearQueue - 从播放队列中清除所有曲目
• CreatePlaylist - 创建歌单
• CreatePlaylistEntry - 歌单中创建曲目
• CreatePlaylistEntrys - 歌单中创建曲目集合
• CreatePlaylistEntrysToMyFavourite - “我最喜爱”中插入曲目集合
• CreateQueueEntry - 播放队列中创建曲目
• CreateQueueEntrys - 播放队列中创建曲目集合
• DeleteMusicInfoFormQueueEntry - 从队列中删除指定曲目
• DeletePlaylist - 删除歌单
• DeletePlaylistEntry - 从歌单中删除曲目
• DeletePlaylistEntryFromMyFavourite - 从“我最喜爱”中删除曲目
• GetMusicInfos - 获取曲目集合
• GetAlbumInfos - 获取专辑集合
• GetArtistInfos - 获取艺术家集合
• GetAlphaGroupedMusicInfo - 获取分组包装好的曲目集合
• GetAlphaGroupedAlbumInfo - 获取分组包装好的专辑集合
• GetAlphaGroupedArtistInfo - 获取分组包装好的艺术家集合
• GetIsMyFavouriteContains - 曲目是否包含在"我最喜爱"中
• GetIsPlaylistContains - 曲目是否包含在歌单中
• GetIsQueueContains - 曲目是否包含在播放队列中
• GetPlaylist - 获取歌单列表
• GetPlaylistEntry - 获取歌单列表
• GetPlaylistInfo - 获取歌单中的曲目
• GetQueueEntry - 获取播放队列中的曲目
• InsertToEndQueueEntry - 插入曲目到播放队列中的末尾
• InsertToEndQueueEntrys - 插入曲目集合到播放队列中的末尾
• InsertToNextQueueEntry - 插入曲目到队列中的下一曲（下一首播放）
• UpdatePlaylist - 更新歌单信息

接口定义：

public interface IMusicInfoManager
{Task ClearQueue();Task<bool> CreatePlaylist(Playlist playlist);Task<bool> CreatePlaylistEntry(MusicInfo musicInfo, long playlistId);Task<bool> CreatePlaylistEntrys(List<MusicInfo> musics, long playlistId);Task<bool> CreatePlaylistEntrys(MusicCollectionInfo musicCollectionInfo, long playlistId);Task<bool> CreatePlaylistEntrysToMyFavourite(List<MusicInfo> musics);Task<bool> CreatePlaylistEntrysToMyFavourite(MusicCollectionInfo musicCollectionInfo);Task<bool> CreatePlaylistEntryToMyFavourite(MusicInfo musicInfo);Task<bool> CreateQueueEntry(MusicInfo musicInfo);Task<bool> CreateQueueEntrys(List<MusicInfo> musicInfos);Task<bool> CreateQueueEntrys(MusicCollectionInfo musics);Task<bool> DeleteMusicInfoFormQueueEntry(MusicInfo musicInfo);Task<bool> DeleteMusicInfoFormQueueEntry(string musicTitle);Task<bool> DeletePlaylist(long playlistId);Task<bool> DeletePlaylist(Playlist playlist);Task<bool> DeletePlaylistEntry(MusicInfo musicInfo, long playlistId);Task<bool> DeletePlaylistEntry(string musicTitle, long playlistId);Task<bool> DeletePlaylistEntryFromMyFavourite(MusicInfo musicInfo);Task<InfoResult<List<AlbumInfo>>> GetAlbumInfos();Task<AlphaGroupedObservableCollection<AlbumInfo>> GetAlphaGroupedAlbumInfo();Task<AlphaGroupedObservableCollection<ArtistInfo>> GetAlphaGroupedArtistInfo();Task<AlphaGroupedObservableCollection<MusicInfo>> GetAlphaGroupedMusicInfo();Task<InfoResult<List<ArtistInfo>>> GetArtistInfos();Task<bool> GetIsMyFavouriteContains(MusicInfo musicInfo);Task<bool> GetIsMyFavouriteContains(string musicTitle);Task<bool> GetIsPlaylistContains(MusicInfo musicInfo, long playlistId);Task<bool> GetIsPlaylistContains(string musicTitle, long playlistId);Task<bool> GetIsQueueContains(string musicTitle);Task<InfoResult<List<MusicInfo>>> GetMusicInfos();Task<List<Playlist>> GetPlaylist();Task<List<MusicInfo>> GetPlaylistEntry(long playlistId);Task<List<MusicInfo>> GetPlaylistEntryFormMyFavourite();Task<List<PlaylistInfo>> GetPlaylistInfo();Task<List<MusicInfo>> GetQueueEntry();Task<bool> InsertToEndQueueEntry(MusicInfo musicInfo);Task<bool> InsertToEndQueueEntrys(List<MusicInfo> musicInfos);Task<bool> InsertToNextQueueEntry(MusicInfo musicInfo, MusicInfo currentMusic);Task<bool> UpdatePlaylist(Playlist playlist);
}

获取本地音乐

Android中的实现

在Android平台中MatoMusic.Core\Platforms\Android\MusicInfoManager.cs

MediaStore类是Android平台的多媒体数据库，它包含了音频，视频，图片等所有多媒体文件信息。

Android扫描服务会在后台自动扫描设备文件资源，将设备上的音乐媒体信息加入到MediaStore数据库中。应用程序通过Android平台提供的ContentProvider包含的API直接从MediaStore中读取相应的媒体信息。

获取设备多媒体信息的实现方式如下：

public IList<MusicInfo> GetAllSongs()
{IList<MusicInfo> songs = new ObservableCollection<MusicInfo>();ICursor mediaCursor, genreCursor, albumCursor;mediaCursor = Application.Context.ContentResolver.Query(MediaStore.Audio.Media.ExternalContentUri,_mediaProjections, null, null,MediaStore.Audio.Media.InterfaceConsts.TitleKey);int artistColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.Artist);int albumColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.Album);int titleColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.Title);int durationColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.Duration);int uriColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.Data);int idColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.Id);int isMusicColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.IsMusic);int albumIdColumn = mediaCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.AlbumId);int isMusic;ulong duration, id;string artist, album, title, uri, genre, artwork, artworkId;if (mediaCursor.MoveToFirst()){do{isMusic = int.Parse(mediaCursor.GetString(isMusicColumn));if (isMusic != 0){ulong.TryParse(mediaCursor.GetString(durationColumn),out duration);artist = mediaCursor.GetString(artistColumn);album = mediaCursor.GetString(albumColumn);title = mediaCursor.GetString(titleColumn);uri = mediaCursor.GetString(uriColumn);ulong.TryParse(mediaCursor.GetString(idColumn), out id);artworkId = mediaCursor.GetString(albumIdColumn);genreCursor = Application.Context.ContentResolver.Query(MediaStore.Audio.Genres.GetContentUriForAudioId("external", (int)id),_genresProjections, null, null, null);int genreColumn = genreCursor.GetColumnIndex(MediaStore.Audio.Genres.InterfaceConsts.Name);if (genreCursor.MoveToFirst()){genre = genreCursor.GetString(genreColumn) ?? string.Empty;}else{genre = string.Empty;}//https://stackoverflow.com/questions/63181820/why-is-album-art-the-only-field-that-returns-null-from-mediastore-when-others-arImageSource artworkImage = null;if (DeviceInfo.Version.Major < 10){albumCursor = Application.Context.ContentResolver.Query(MediaStore.Audio.Albums.ExternalContentUri,_albumProjections,$"{MediaStore.Audio.Albums.InterfaceConsts.Id}=?",new string[] { artworkId },null);int artworkColumn = albumCursor.GetColumnIndex(MediaStore.Audio.Media.InterfaceConsts.AlbumArt);if (albumCursor.MoveToFirst()){artwork = albumCursor.GetString(artworkColumn) ?? string.Empty;}else{artwork = String.Empty;}albumCursor?.Close();artworkImage = artwork;}else{var extUrl = MediaStore.Audio.Albums.ExternalContentUri;var albumArtUri = ContentUris.WithAppendedId(extUrl, long.Parse(artworkId));try{//var art = System.IO.Path.Combine (Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "albumart" + artworkId + ".jpg");var art = System.IO.Path.Combine(Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryDocuments).AbsolutePath, "albumart" + artworkId + ".jpg");var bitmap = Application.Context.ContentResolver.LoadThumbnail(albumArtUri, new Android.Util.Size(1024, 1024), null);var h = bitmap.Height;var w = bitmap.Width;var bb = bitmap.ByteCount;using (Stream ms = new FileStream(art, FileMode.Create)){bitmap.Compress(Bitmap.CompressFormat.Png, 100, ms);bitmap.Recycle();}artworkImage = art;}catch (Exception e){System.Console.WriteLine(e.Message);}}songs.Add(new MusicInfo(){Id = (int)id,Title = title,Artist = artist,AlbumTitle = album,Genre = genre,Duration = duration / 1000,Url = uri,AlbumArt = artworkImage});genreCursor?.Close();}} while (mediaCursor.MoveToNext());}mediaCursor?.Close();return songs;}

获取音乐信息集合

public partial async Task<InfoResult<List<MusicInfo>>> GetMusicInfos()
{List<MusicInfo> musicInfos;var result = false;if (await MediaLibraryAuthorization()){musicInfos = await Task.Run(() =>{var Infos = (from item in GetAllSongs()select new MusicInfo(){Id = item.Id,Title = item.Title,Duration = item.Duration,Url = item.Url,AlbumTitle = item.AlbumTitle,Artist = item.Artist,AlbumArt = item.AlbumArt,GroupHeader = GetGroupHeader(item.Title),IsFavourite = GetIsMyFavouriteContains(item.Title).Result,IsInitFinished = true}).ToList();return Infos;});result = true;}else{musicInfos = new List<MusicInfo>();result = false;}return new InfoResult<List<MusicInfo>>(result, musicInfos);}

iOS中的实现

在iOS平台中MatoMusic.Core\Platforms\iOS\MusicInfoManager.cs

在iOS平台中获取音乐信息要简单得多，MPMediaQuery这个类获取通系统自带的‘音乐’软件下载的，或通过iTunes导入的本地歌曲文件

MPMediaQuery 类使用方式可以参考官方文档

获取音乐信息集合

public partial async Task<InfoResult<List<MusicInfo>>> GetMusicInfos()
{List<MusicInfo> musicInfos;var result = false;if (await MediaLibraryAuthorization()){musicInfos = await Task.Run(() =>{var Infos = (from item in MediaQuery.Itemswhere item.MediaType == MPMediaType.Musicselect new MusicInfo(){Id = (int)item.PersistentID,Title = item.Title,Url = item.AssetURL.ToString(),Duration = Convert.ToUInt64(item.PlaybackDuration),AlbumTitle = item.AlbumTitle,Artist = item.Artist,AlbumArt = GetAlbumArtSource(item),GroupHeader = GetGroupHeader(item.Title),IsFavourite = GetIsMyFavouriteContains(item.Title).Result,IsInitFinished = true}).ToList();return Infos;});result = true;}else{musicInfos = new List<MusicInfo>();result = false;}return new InfoResult<List<MusicInfo>>(result, musicInfos);}

Windows中的实现

在Windows设备中，需要指定一个主目录来扫描音乐文件，我们指定一个缺省目录，如“音乐”文件夹（KnownFolders.MusicLibrary），好跟之前两个平台的行为保持一致

private async Task<List<MusicInfo>> SetMusicListAsync(StorageFolder musicFolder = null)
{var localSongs = new List<MusicInfo>();List<StorageFile> songfiles = new List<StorageFile>();if (musicFolder == null){musicFolder = KnownFolders.MusicLibrary;}await GetLocalSongsAysnc(songfiles, musicFolder);localSongs = await PopulateSongListAsync(songfiles);return localSongs;}

递归调用GetLocalSongsAysnc，遍历主目录以及其子目录的所有.mp3文件

private async Task GetLocalSongsAysnc(List<StorageFile> songFiles, StorageFolder parent)
{foreach (var item in await parent.GetFilesAsync()){if (item.FileType == ".mp3")songFiles.Add(item);}foreach (var folder in await parent.GetFoldersAsync()){await GetLocalSongsAysnc(songFiles, folder);}
}

从本地文件读取音频信息，转成曲目信息

private async Task<List<MusicInfo>> PopulateSongListAsync(List<StorageFile> songFiles)
{var localSongs = new List<MusicInfo>();int Id = 1;foreach (var file in songFiles){MusicInfo song = new MusicInfo();// 1. 获取文件信息MusicProperties musicProperty = await file.Properties.GetMusicPropertiesAsync();if (!string.IsNullOrEmpty(musicProperty.Title))song.Title = musicProperty.Title;else{song.Title = file.DisplayName;}StorageItemThumbnail currentThumb = await file.GetThumbnailAsync(ThumbnailMode.MusicView, 60, ThumbnailOptions.UseCurrentScale);// 2.将文件信息转换为数据模型string coverUri = "ms-appx:///Assets/Default/Default.jpg";song.Id = Id;song.Url = file.Path;song.GroupHeader = GetGroupHeader(song.Title);if (!string.IsNullOrEmpty(musicProperty.Artist))song.Artist = musicProperty.Artist;elsesong.Artist = "未知歌手";if (!string.IsNullOrEmpty(musicProperty.Album))song.AlbumTitle = musicProperty.Album;elsesong.AlbumTitle = "未知唱片";song.Duration = (ulong)musicProperty.Duration.TotalSeconds;//3. 添加至UI集合中var task01 = SaveImagesAsync(file, song);var result = await task01;var task02 = task01.ContinueWith((e) =>{if (result.IsSucess){song.AlbumArtPath = result.Result;}else{song.AlbumArtPath = coverUri;}});Task.WaitAll(task01, task02);song.IsInitFinished = true;localSongs.Add(song);Id++;}return localSongs;
}

获取音乐信息集合

public partial async Task<InfoResult<List<MusicInfo>>> GetMusicInfos()
{List<MusicInfo> musicInfos;var result = false;if (await MediaLibraryAuthorization()){musicInfos = await SetMusicListAsync();result = true;}else{musicInfos = new List<MusicInfo>();result = false;}return new InfoResult<List<MusicInfo>>(result, musicInfos);}

获取专辑和艺术家

专辑信息包含了音乐集合

获取专辑和艺术家的跨平台的实现方式大同小异，以Android平台为例

GetAlbumInfos方法用于获取AlbumInfo集合

public partial async Task<InfoResult<List<AlbumInfo>>> GetAlbumInfos()
{List<AlbumInfo> albumInfo;var result = false;if (await MediaLibraryAuthorization()){var isSucc = await GetMusicInfos();if (!isSucc.IsSucess){//CommonHelper.ShowNoAuthorized();}albumInfo = await Task.Run(() =>{var info = (from item in isSucc.Resultgroup item by item.AlbumTitleinto cselect new AlbumInfo(){Title = c.Key,GroupHeader = GetGroupHeader(c.Key),AlbumArt = c.FirstOrDefault().AlbumArt,Musics = new ObservableCollection<MusicInfo>(c.Select(d => new MusicInfo(){Id = d.Id,Title = d.Title,Duration = d.Duration,Url = d.Url,AlbumTitle = d.AlbumTitle,Artist = d.Artist,AlbumArt = d.AlbumArt,IsFavourite = GetIsMyFavouriteContains(d.Title).Result,IsInitFinished = true}))}).ToList();return info;});result = true;}else{albumInfo = new List<AlbumInfo>();result = false;}return new InfoResult<List<AlbumInfo>>(result, albumInfo);}

GetArtistInfos方法用于获取ArtistInfo集合

public partial async Task<InfoResult<List<ArtistInfo>>> GetArtistInfos()
{List<ArtistInfo> artistInfo;var result = false;if (await MediaLibraryAuthorization()){var isSucc = await GetMusicInfos();if (!isSucc.IsSucess){//CommonHelper.ShowNoAuthorized();}artistInfo = await Task.Run(() =>{var info = (from item in isSucc.Resultgroup item by item.Artistinto cselect new ArtistInfo(){Title = c.Key,GroupHeader = GetGroupHeader(c.Key),Musics = new ObservableCollection<MusicInfo>(c.Select(d => new MusicInfo(){Id = d.Id,Title = d.Title,Duration = d.Duration,Url = d.Url,AlbumTitle = d.AlbumTitle,Artist = d.Artist,AlbumArt = d.AlbumArt,IsFavourite = GetIsMyFavouriteContains(d.Title).Result,IsInitFinished = true}))}).ToList();return info;});result = true;}else{artistInfo = new List<ArtistInfo>();result = false;}return new InfoResult<List<ArtistInfo>>(result, artistInfo);
}

项目地址

GitHub:MatoMusic