[MAUI 项目实战] 音乐播放器（二）：播放内核
![[MAUI 项目实战] 音乐播放器（二）：播放内核](https://img2023.cnblogs.com/blog/644861/202302/644861-20230212002606862-830095990.png)
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。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
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 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<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-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<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.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<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;
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<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.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<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.Result
group item by item.Artist
into c
select 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
本文来自博客园，作者：林晓lx，转载请注明原文链接：https://www.cnblogs.com/jevonsflash/p/17113143.html
