WCF Streaming File Transfer ON .NET 4

问题:

I need a good example on WCF Streaming File Transfer.

I have found several and tried them but the posts are old and I am wokding on .net 4 and IIS 7 so there are some problems.

Can you gives me a good and up-to-date example on that.

回答1:

The following answers detail using a few techniques for a posting binary data to a restful service.

• Post binary data to a RESTful application
• What is a good way to transfer binary data to a HTTP REST API service?
• Bad idea to transfer large payload using web services?

The following code is a sample of how you could write a RESTful WCF service and is by no means complete but does give you an indication on where you could start.

Sample Service, note that this is NOT production ready code.

[ServiceContract]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
public class FileService
{
    private IncomingWebRequestContext m_Request;
    private OutgoingWebResponseContext m_Response;

    [WebGet(UriTemplate = "{appName}/{id}?action={action}")]
    public Stream GetFile(string appName, string id, string action)
    {
        var repository = new FileRepository();
        var response = WebOperationContext.Current.OutgoingResponse;
        var result = repository.GetById(int.Parse(id));

        if (action != null && action.Equals("download", StringComparison.InvariantCultureIgnoreCase))
        {
            response.Headers.Add("Content-Disposition", string.Format("attachment; filename={0}", result.Name));
        }

        response.Headers.Add(HttpResponseHeader.ContentType, result.ContentType);
        response.Headers.Add("X-Filename", result.Name);

        return result.Content;
    }

    [WebInvoke(UriTemplate = "{appName}", Method = "POST")]
    public void Save(string appName, Stream fileContent)
    {
        try
        {
            if (WebOperationContext.Current == null) throw new InvalidOperationException("WebOperationContext is null.");

            m_Request = WebOperationContext.Current.IncomingRequest;
            m_Response = WebOperationContext.Current.OutgoingResponse;

            var file = CreateFileResource(fileContent, appName);

            if (!FileIsValid(file)) throw new WebFaultException(HttpStatusCode.BadRequest);

            SaveFile(file);

            SetStatusAsCreated(file);
        }
        catch (Exception ex)
        {
            if (ex.GetType() == typeof(WebFaultException)) throw;
            if (ex.GetType().IsGenericType && ex.GetType().GetGenericTypeDefinition() == typeof(WebFaultException<>)) throw;

            throw new WebFaultException<string>("An unexpected error occurred.", HttpStatusCode.InternalServerError);
        }
    }

    private FileResource CreateFileResource(Stream fileContent, string appName)
    {
        var result = new FileResource();

        fileContent.CopyTo(result.Content);
        result.ApplicationName = appName;
        result.Name = m_Request.Headers["X-Filename"];
        result.Location = @"C:\SomeFolder\" + result.Name;
        result.ContentType = m_Request.Headers[HttpRequestHeader.ContentType] ?? this.GetContentType(result.Name);
        result.DateUploaded = DateTime.Now;

        return result;
    }

    private string GetContentType(string filename)
    {
        // this should be replaced with some form of logic to determine the correct file content type (I.E., use registry, extension, xml file, etc.,)
        return "application/octet-stream";
    }

    private bool FileIsValid(FileResource file)
    {
        var validator = new FileResourceValidator();
        var clientHash = m_Request.Headers[HttpRequestHeader.ContentMd5];

        return validator.IsValid(file, clientHash);
    }

    private void SaveFile(FileResource file)
    {
        // This will persist the meta data about the file to a database (I.E., size, filename, file location, etc)
        new FileRepository().AddFile(file);
    }

    private void SetStatusAsCreated(FileResource file)
    {
        var location = new Uri(m_Request.UriTemplateMatch.RequestUri.AbsoluteUri + "/" + file.Id);
        m_Response.SetStatusAsCreated(location);
    }
}

Sample Client, note that this is NOT production ready code.

// *********************************
// Sample Client
// *********************************
private void UploadButton_Click(object sender, EventArgs e)
{
    var uri = "http://dev-fileservice/SampleApplication"
    var fullFilename = @"C:\somefile.txt";
    var fileContent = File.ReadAllBytes(fullFilename);

    using (var webClient = new WebClient())
    {
        try
        {
            webClient.Proxy = null;
            webClient.Headers.Add(HttpRequestHeader.ContentMd5, this.CalculateFileHash());
            webClient.Headers.Add("X-DaysToKeep", DurationNumericUpDown.Value.ToString());
            webClient.Headers.Add("X-Filename", Path.GetFileName(fullFilename));
            webClient.UploadData(uri, "POST", fileContent);

            var fileUri = webClient.ResponseHeaders[HttpResponseHeader.Location];
            Console.WriteLine("File can be downloaded at" + fileUri);
        }
        catch (Exception ex)
        {
            var exception = ex.Message;
        }
    }
}

private string CalculateFileHash()
{
    var hash = MD5.Create().ComputeHash(File.ReadAllBytes(@"C:\somefile.txt"));
    var sb = new StringBuilder();

    for (int i = 0; i < hash.Length; i++)
    {
        sb.Append(hash[i].ToString("x2"));
    }

    return sb.ToString();
}

private void DownloadFile()
{
    var uri = "http://dev-fileservice/SampleApplication/1" // this is the URL returned by the Restful file service

    using (var webClient = new WebClient())
    {
        try
        {
            webClient.Proxy = null;
            var fileContent = webClient.DownloadData(uri);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }
}