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全球观焦点：深入解读.NET MAUI音乐播放器项目（二）：播放内核

来源：博客园

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。


(资料图片仅供参考)

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 OnPlayFinished;    event EventHandler OnRebuildMusicInfosFinished;    event EventHandler OnProgressChanged;    event EventHandler OnPlayStatusChanged;    public IMusicInfoManager MusicInfoManager { get; set; }    int[] ShuffleMap { get; }    List 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 queueRepository,    IRepository playlistItemRepository,    IRepository 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> 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 queueEntrys        join musicInfo in _musicInfos        on queue.MusicInfoId equals musicInfo.Id        orderby queue.Rank        select 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 CreateQueueEntrys(List musicInfos){    var lastItemRank = queueRepository.GetAll().OrderBy(c => c.Rank).Select(c => c.Rank).LastOrDefault();    var entrys = new List();    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 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 CreatePlaylist(Playlist playlist);    Task CreatePlaylistEntry(MusicInfo musicInfo, long playlistId);    Task CreatePlaylistEntrys(List musics, long playlistId);    Task CreatePlaylistEntrys(MusicCollectionInfo musicCollectionInfo, long playlistId);    Task CreatePlaylistEntrysToMyFavourite(List musics);    Task CreatePlaylistEntrysToMyFavourite(MusicCollectionInfo musicCollectionInfo);    Task CreatePlaylistEntryToMyFavourite(MusicInfo musicInfo);    Task CreateQueueEntry(MusicInfo musicInfo);    Task CreateQueueEntrys(List musicInfos);    Task CreateQueueEntrys(MusicCollectionInfo musics);    Task DeleteMusicInfoFormQueueEntry(MusicInfo musicInfo);    Task DeleteMusicInfoFormQueueEntry(string musicTitle);    Task DeletePlaylist(long playlistId);    Task DeletePlaylist(Playlist playlist);    Task DeletePlaylistEntry(MusicInfo musicInfo, long playlistId);    Task DeletePlaylistEntry(string musicTitle, long playlistId);    Task DeletePlaylistEntryFromMyFavourite(MusicInfo musicInfo);    Task>> GetAlbumInfos();    Task> GetAlphaGroupedAlbumInfo();    Task> GetAlphaGroupedArtistInfo();    Task> GetAlphaGroupedMusicInfo();    Task>> GetArtistInfos();    Task GetIsMyFavouriteContains(MusicInfo musicInfo);    Task GetIsMyFavouriteContains(string musicTitle);    Task GetIsPlaylistContains(MusicInfo musicInfo, long playlistId);    Task GetIsPlaylistContains(string musicTitle, long playlistId);    Task GetIsQueueContains(string musicTitle);    Task>> GetMusicInfos();    Task> GetPlaylist();    Task> GetPlaylistEntry(long playlistId);    Task> GetPlaylistEntryFormMyFavourite();    Task> GetPlaylistInfo();    Task> GetQueueEntry();    Task InsertToEndQueueEntry(MusicInfo musicInfo);    Task InsertToEndQueueEntrys(List musicInfos);    Task InsertToNextQueueEntry(MusicInfo musicInfo, MusicInfo currentMusic);    Task 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 GetAllSongs(){    IList songs = new ObservableCollection();    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-ar                ImageSource 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>> GetMusicInfos(){    List 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();        result = false;    }    return new InfoResult>(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>> GetMusicInfos(){    List musicInfos;    var result = false;    if (await MediaLibraryAuthorization())    {        musicInfos = await Task.Run(() =>        {            var Infos = (from item in MediaQuery.Items                            where item.MediaType == MPMediaType.Music                            select 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();        result = false;    }    return new InfoResult>(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> SetMusicListAsync(StorageFolder musicFolder = null){    var localSongs = new List();    List songfiles = new List();    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 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> PopulateSongListAsync(List songFiles){    var localSongs = new List();    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;        else            song.Artist = "未知歌手";        if (!string.IsNullOrEmpty(musicProperty.Album))            song.AlbumTitle = musicProperty.Album;        else            song.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>> GetMusicInfos(){    List musicInfos;    var result = false;    if (await MediaLibraryAuthorization())    {        musicInfos = await SetMusicListAsync();        result = true;    }    else    {        musicInfos = new List();        result = false;    }    return new InfoResult>(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>> GetAlbumInfos(){    List 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.Result                        group item by item.AlbumTitle                into c                        select new AlbumInfo()                        {                            Title = c.Key,                            GroupHeader = GetGroupHeader(c.Key),                            AlbumArt = c.FirstOrDefault().AlbumArt,                            Musics = new ObservableCollection(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();        result = false;    }    return new InfoResult>(result, albumInfo);}

GetArtistInfos方法用于获取ArtistInfo集合

public partial async Task>> GetArtistInfos(){    List 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.Result                        group item by item.Artist                into c                        select new ArtistInfo()                        {                            Title = c.Key,                            GroupHeader = GetGroupHeader(c.Key),                            Musics = new ObservableCollection(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();        result = false;    }    return new InfoResult>(result, artistInfo);}

项目地址

GitHub:MatoMusic

关键词： 获取分组