UWP - 将MediaFile转换为StorageFile-Java 学习之路

我需要将类型 Plugin.Media.Abstractions.MediaFile 转换为 Windows.Storage.StorageFile .

原因是我想要通过路径上传到服务器的 MediaFile ，但是在UWP中你必须使用StorageFiles而不是文件路径，否则UWP不会't know that the user has the permission for this file and just denies the access. So I want to convert the MediaFile to a StorageFile to be able to create a copy of the file in the temporary folder of the user. Files in this folder can be accessed by the file'的路径 .

这就是我尝试过的：

Stream stream = _mediaFile.GetStream();
StreamReader reader = new StreamReader(stream, Encoding.UTF8);
string streamText = reader.ReadToEnd();

_websocketManager.sendFileMessage(_selectedChat.chatId, _nachrichttext, streamText);

sendFileMessage() 是一个来自接口的方法，所以参数必须是一个字符串，我可以't change that. Originally this string is supposed to be the path, so it'一个廉价的解决方法由我但是's legit for what I' m试图实现 .

在WebsocketManager中，这是我的方法 sendFileMessage() ：

byte[] byteArray = Encoding.UTF8.GetBytes(streamText);
MemoryStream stream = new MemoryStream(byteArray);

StorageFolder temporaryFolder = ApplicationData.Current.TemporaryFolder;

var temporaryFile = await temporaryFolder.CreateFileAsync("temporaryFile", CreationCollisionOption.ReplaceExisting);

using (var fileStream = File.Create(temporaryFolder.Path + "\\TemporaryFile")) // TODO: How to data type? (.png, .jpg, ...)
{
    stream.Seek(0, SeekOrigin.Begin);
    stream.CopyTo(fileStream);
}

string filePath = temporaryFile.Path;
string remoteFilePath = null;
if (!string.IsNullOrEmpty(filePath))
{
    await StorageFile.GetFileFromPathAsync(filePath);
    remoteFilePath = await uploadFile(filePath);
}
    dataWriter.WriteString(WebsocketRequestFactory.Create(SocketEventsEnm.MESSAGE_OUT, chatId, message, remoteFilePath, TypeEnm.IMAGE));
await SendData(dataWriter);
await temporaryFile.DeleteAsync();

另外，正如我在代码中评论的那样，我需要找出 MediaFile 是哪种数据类型（.png，.jpg等） .

1 回答

您可以参考xamarin官方文档Working with Files来读取和写入文件，我们需要在每个平台上使用本机文件API .

对于UWP应用程序，您可以在便携式项目中创建一个接口 ISaveAndLoad ，如下所示：

public interface ISaveAndLoad
{
    void SaveImage(string filename, Stream filestream);

    Task<string> LoadImage(string filename);
}

然后在你的UWP应用程序中创建一个类继承并实现这个 ISaveAndLoad 接口，如下所示：

public class SaveAndLoad_UWP : ISaveAndLoad
{
    public async Task<string> LoadImage(string filename)
    {
        StorageFolder local = ApplicationData.Current.LocalFolder;
        StorageFile file = await local.GetFileAsync(filename);
        return file.Path;
    }

    public async void SaveImage(string filename, Stream filestream)
    {
        StorageFolder localFolder = ApplicationData.Current.LocalFolder;
        StorageFile File = await localFolder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);
        using (var stream = await File.OpenStreamForWriteAsync())
        {
            await filestream.CopyToAsync(stream);
        }
    }
}

最后，当您选择图像时，可以将 MediaFile 转换为 StorageFile 并获取临时文件的路径，如下所示：

var file = await CrossMedia.Current.PickPhotoAsync(); //pick a file

if (file == null)
    return;
var path = file.Path;
var filetype = path.Split('.').Last(); //get file type
var filestream = file.GetStream();

DependencyService.Get<ISaveAndLoad>().SaveImage("temp." + filetype, filestream); //save file

var temppath = DependencyService.Get<ISaveAndLoad>().LoadImage("temp." + filetype); //get temp file's path

回复于 2024-04-29T06:04:29+08:00

UWP - 将MediaFile转换为StorageFile

1 回答

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