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RecyclerView:在不阻塞UI线程的情况下重新加载数据

android-recyclerview android

innomotion media · 技术社区 · 7 年前

我正在开发一个应用程序,可以扫描你的手机中的MP3,然后将它们全部放入一个列表中,由 recyclerview 让你在它们之间滚动播放。

回收服务 回收服务 ,但我不知道如何填充重新加载适配器,以便它不会一次全部重新加载,而是一步一步地重新加载。这就是ATM的外观:

重新加载适配器:

public class MySimpleItemLoader
{
    public List<MP3object> mP3Objects { get; private set; }
    public bool IsBusy { get; set; }
    public int CurrentPageValue { get; set; }
    public bool CanLoadMoreItems { get; private set; }

    public MySimpleItemLoader(List<MP3object> mp3)
    {
        this.mP3Objects = mp3;
    }

    public void LoadMoreItems(int itemsPerPage)
    {
        IsBusy = true;
        for (int i = CurrentPageValue; i < CurrentPageValue + itemsPerPage; i++)
        {
            mP3Objects.Add(new MP3object() { AlbumName = string.Format("This is item {0:0000}", i) });
        }

        CanLoadMoreItems = true;
        CurrentPageValue = mP3Objects.Count;
        IsBusy = false;
    }


}

我的主要活动,在这里我加载一个包含所有mp3的列表(需要很长时间):

    private void PopulateMP3List(List<string> content)
    {
       mp3 = new List<MP3object>();        
       foreach (string obj in content)
       {
           WriteMetaDataToFileList(obj);        
       }
    }



    void WriteMetaDataToFileList(string obj)
    {
        reader.SetDataSource(obj);

        //Write Mp3 as object to global list
        MP3object ob = new MP3object();
        {
            if(reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyTitle) != "" && reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyTitle) != null)
            {
                ob.SongName = reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyTitle);
            }
            else
            {
                ob.SongName = Resources.GetString(Resource.String.Unknown);
            }

            if (reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyArtist) != "" && reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyArtist) != null)
            {
                ob.ArtistName = reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyArtist);
            }
            else
            {
                ob.ArtistName = Resources.GetString(Resource.String.Unknown);
            }

            if (reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyAlbum) != "" && reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyAlbum) != null)
            {
                ob.AlbumName = reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyAlbum);
            }
            else
            {
                ob.AlbumName = Resources.GetString(Resource.String.Unknown);
            }

            if (reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyYear) != "" && reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyYear) != null)
            {
                ob.Year = reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyYear);
            }
            else
            {
                ob.Year = Resources.GetString(Resource.String.Unknown);
            }

            if (reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyYear) != "" && reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyYear) != null)
            {
                ob.Year = reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyYear);
            }
            else
            {
                ob.Year = Resources.GetString(Resource.String.Unknown);
            }

            ob.Mp3Uri = obj; // can never be unknown!

            ob.DurationInSec = int.Parse(reader.ExtractMetadata(MediaMetadataRetriever.MetadataKeyDuration)) / 1000; // can never be unknown, div by 1000 to get sec not millis
        }
        mp3.Add(ob);

    }

    public List<string> ReturnPlayableMp3(bool sdCard)
    {
        List<string> res = new List<string>();
        string phyle;
        string path1 = null;

        if(sdCard) // get mp3 from SD card
        {
            string baseFolderPath = "";

            try
            {
                bool getSDPath = true;

                Context context = Application.Context;
                Java.IO.File[] dirs = context.GetExternalFilesDirs(null);

                foreach (Java.IO.File folder in dirs)
                {
                    bool IsRemovable = Android.OS.Environment.InvokeIsExternalStorageRemovable(folder);
                    bool IsEmulated = Android.OS.Environment.InvokeIsExternalStorageEmulated(folder);

                    if (getSDPath ? IsRemovable && !IsEmulated : !IsRemovable && IsEmulated)
                        baseFolderPath = folder.Path;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("GetBaseFolderPath caused the following exception: {0}", ex);
            }

            string xy = baseFolderPath.Remove(18); // This is result after this, but this hard coded solution could be a problem on different phones.: "/storage/05B6-2226/Android/data/Media_Player.Media_Player/files"

            path1 = xy;
            // path to SD card and MUSIC "/storage/05B6-2226/"
        }
        else // get Mp3 from internal storage
        {
                path1 = Android.OS.Environment.ExternalStorageDirectory.ToString();
        }

        var mp3Files = Directory.EnumerateFiles(path1, "*.mp3", SearchOption.AllDirectories);

        foreach (string currentFile in mp3Files)
        {
            phyle = currentFile;
            res.Add(phyle);
        }

        return res;
    }

我该如何转换它,以便加载不在主活动中发生,而是在回收器视图重新加载适配器中需要它的地方发生?

非常感谢:)

1 回复 | 直到 7 年前

2hamed 7 年前

我想你不明白 RecyclerView 正确使用。这个 回收服务
任何数据加载到 回收服务

为了纠正这个错误,您需要将数据加载到 回收服务 的适配器,然后通知它投射更改。如果你有大量的数据需要很长时间来加载,你可以用较小的步骤来完成,并更新每一步之后。举例来说,你在每一步100首歌中加载700首歌。

val audioFiles = mutableListOf<String>()
Observable.create{ e ->
    for{
        val offset = audioFiles.size
        // load your files here
        if(audioFiles.size % 100){
            e.onNext(offset)
        }
    }
    e.onComplete()
}
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe{ offset ->
    mAdapter.notifyItemRangeInserted(offset, offset+100)
}