Question

我需要一个关于WCF流式文件传输的好例子。

我找到了几个并尝试了它们，但帖子很旧，我在.net 4和IIS 7上玩耍，所以有一些问题。

你能否给我一个很好的最新例子。

Answer 1

以下答案详细介绍了如何使用一些技术将二进制数据发布到一个宁静的服务。

以下代码是您如何编写RESTful WCF服务的示例，但并不完整，但它会告诉您可以从哪里开始。

示例服务，请注意这是 NOT 生产就绪代码。

[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);
    }
}

示例客户，请注意，这是 NOT 生产就绪代码。

// *********************************
// 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);
        }
    }
}

WCF流式文件传输在.NET 4上

1 个答案: