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この質問の背景は、私が開発している仮想ファイルシステムに基づいています。私が使用しているコンセプトは、さまざまなタイプのストレージタイプ、つまりローカルファイルシステム、ドロップボックス、Amazons3用の仮想パスプロバイダーです。仮想ファイルの基本クラスは次のようになります。

public abstract class CommonVirtualFile : VirtualFile {
    public virtual string Url {
        get { throw new NotImplementedException(); }
    }
    public virtual string LocalPath {
        get { throw new NotImplementedException(); }
    }
    public override Stream Open() {
        throw new NotImplementedException();
    }
    public virtual Stream Open(FileMode fileMode) {
        throw new NotImplementedException();
    }
    protected CommonVirtualFile(string virtualPath) : base(virtualPath) { }
}

2番目のOpenメソッドの実装は、私の質問のすべてです。ローカルファイルシステムの実装を見ると、つまりファイルをディスクに保存すると、次のようになります。

public override Stream Open(FileMode fileMode) {
    return new FileStream("The_Path_To_The_File_On_Disk"), fileMode);
}

ローカルファイルシステムにファイルを保存したい場合、これは次のようになります。

    const string virtualPath = "/assets/newFile.txt";
    var file = HostingEnvironment.VirtualPathProvider.GetFile(virtualPath) as CommonVirtualFile;
    if (file == null) {
        var virtualDir = VirtualPathUtility.GetDirectory(virtualPath);
        var directory = HostingEnvironment.VirtualPathProvider.GetDirectory(virtualDir) as CommonVirtualDirectory;
        file = directory.CreateFile(VirtualPathUtility.GetFileName(virtualPath));
    }
    byte[] fileContent;
    using (var fileStream = new FileStream(@"c:\temp\fileToCopy.txt", FileMode.Open, FileAccess.Read)) {
        fileContent = new byte[fileStream.Length];
        fileStream.Read(fileContent, 0, fileContent.Length);
    }
    // write the content to the local file system
    using (Stream stream = file.Open(FileMode.Create)) {
        stream.Write(fileContent, 0, fileContent.Length);
    }

私が欲しいのは、Amazon s3仮想パスプロバイダーに切り替えた場合、このコードを変更せずに直接機能させたいので、要約すると、Amazon s3 sdkを使用してこれを解決するにはどうすればよいですか、Open（FileMode fileMode）私のamazon s3仮想パスプロバイダーのメソッド？

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1 に答える 1

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Hey i stood for this problem, too, and i solved it implementing a stream.

Here is my way i did it maybe it helps:

public static Stream OpenStream(S3TransferUtility transferUtility, string key)
    {                     
        byte[] buffer  = new byte[Buffersize + Buffersize/2];

        S3CopyMemoryStream s3CopyStream =
            new S3CopyMemoryStream(key, buffer, transferUtility)
            .WithS3CopyFileStreamEvent(CreateMultiPartS3Blob);

        return s3CopyStream;
    }

My Stream with constructor overrides the close and write(array, offset, count) methods and upload the stream to amazon s3 partly.

public class S3CopyMemoryStream : MemoryStream
    {

        public S3CopyMemoryStream WithS3CopyFileStreamEvent(StartUploadS3CopyFileStreamEvent doing)
        {
            S3CopyMemoryStream s3CopyStream = new S3CopyMemoryStream(this._key, this._buffer, this._transferUtility);

            s3CopyStream.StartUploadS3FileStreamEvent = new S3CopyMemoryStream.StartUploadS3CopyFileStreamEvent(CreateMultiPartS3Blob);

            return s3CopyStream;
        }

        public S3CopyMemoryStream(string key, byte[] buffer, S3TransferUtility transferUtility)
            : base(buffer)
        {
            if (buffer.LongLength > int.MaxValue)
                throw new ArgumentException("The length of the buffer may not be longer than int.MaxValue", "buffer");

            InitiatingPart = true;
            EndOfPart = false;
            WriteCount = 1;
            PartETagCollection = new List<PartETag>();

            _buffer = buffer;
            _key = key;
            _transferUtility = transferUtility;
        }

The event StartUploadS3FileStreamEvent invokes a call that initiate, uploadpart and complete the upload.

Alternatively you could implement a FileStream which is much easier because you can use 

TransferUtilityUploadRequest request =
            new TransferUtilityUploadRequest()
            .WithAutoCloseStream(false).WithBucketName(
                transferUtility.BucketName)
                .WithKey(key)
                .WithPartSize(stream.PartSize)
                .WithInputStream(stream) as TransferUtilityUploadRequest;

        transferUtility.Upload(request);

at the close method of the overriden FileStream. The disadvantage is that you have to write the whole data to the disk first and then you can upload it.

于 2012-11-30T09:53:05.347 に答える