在ASP.NET Web Api C#中通过流发送和接收大型文件

Question

我正在开发一个项目,我需要通过流从客户端向服务器发送大型音频文件.我正在使用ASP.NET Web Api在客户端和服务器之间进行通信.我的客户端有一个"SendFile"方法,我相信它工作正常,但我不知道如何让我的服务器接收我通过流发送的数据.到目前为止,我的客户端代码如下所示:

 private const int MAX_CHUNK_SIZE = (1024 * 5000);
    private HttpWebRequest webRequest = null;
    private FileStream fileReader = null;
    private Stream requestStream = null;

    public bool SendAudio(string uri, string file)
    {
        byte[] fileData;
        fileReader = new FileStream(file, FileMode.Open, FileAccess.Read);
        webRequest = (HttpWebRequest)WebRequest.Create(uri);
        webRequest.Method = "POST";
        webRequest.ContentLength = fileReader.Length;
        webRequest.Timeout = 600000;
        webRequest.Credentials = CredentialCache.DefaultCredentials;
        webRequest.AllowWriteStreamBuffering = false;
        requestStream = webRequest.GetRequestStream();

        long fileSize = fileReader.Length;
        long remainingBytes = fileSize;
        int numberOfBytesRead = 0, done = 0;

        while (numberOfBytesRead < fileSize)
        {
            SetByteArray(out fileData, remainingBytes);
            done = WriteFileToStream(fileData, requestStream);
            numberOfBytesRead += done;
            remainingBytes -= done;
        }
        fileReader.Close();
        return true;
    }

    public int WriteFileToStream(byte[] fileData, Stream requestStream)
    {
        int done = fileReader.Read(fileData, 0, fileData.Length);
        requestStream.Write(fileData, 0, fileData.Length);

        return done;
    }

    private void SetByteArray(out byte[] fileData, long bytesLeft)
    {
        fileData = bytesLeft < MAX_CHUNK_SIZE ? new byte[bytesLeft] : new byte[MAX_CHUNK_SIZE];
    }

我的服务器看起来像这样:

    [HttpPost]
    [ActionName("AddAudio")]
    public async Task<IHttpActionResult> AddAudio([FromUri]string name)
    {
        try
        {
            isReceivingFile = true;
            byte[] receivedBytes = await Request.Content.ReadAsByteArrayAsync();
            if (WriteAudio(receivedBytes, name) == true)
            {
                isReceivingFile = false;
                return Ok();
            }
            else
            {
                isReceivingFile = false;
                return BadRequest("ERROR: Audio could not be saved on server.");
            }
        }
        catch (Exception ex)
        {
            isReceivingFile = false;
            return BadRequest("ERROR: Audio could not be saved on server.");
        }
    }

    public bool WriteAudio(byte[] receivedBytes, string fileName)
    {
        string file = Path.Combine(@"C:\Users\username\Desktop\UploadedFiles", fileName);
        using (FileStream fs = File.Create(file))
        {
            fs.Write(receivedBytes, 0, receivedBytes.Length);
        }
        return true;
    }

服务器代码具有我为其编写的原始代码,然后决定尝试使用流.如果我发送一个小文件(30 MB以下),服务器代码仍然有效,但如果我发送一个大文件,我的服务器会出现"outofmemoryexception".我无法弄清楚如何让服务器通过流接收数据.在我寻找解决方案的过程中,我遇到了很多带套接字和TCPClient的例子,但这不是我们想要在这个项目上做的.请帮忙吗？

Answer 1

如果我发送一个大文件,我的服务器会出现"outofmemoryexception"

好吧,它正在将整个流读入内存:

byte[] receivedBytes = await Request.Content.ReadAsByteArrayAsync();

您要做的是将流从一个位置复制到另一个位置,而不是一次将其全部加载到内存中.这样的事情应该有效:

[HttpPost]
[ActionName("AddAudio")]
public async Task<IHttpActionResult> AddAudio([FromUri]string name)
{
  try
  {
    string file = Path.Combine(@"C:\Users\username\Desktop\UploadedFiles", fileName);
    using (FileStream fs = new FileStream(file, FileMode.Create, FileAccess.Write,
        FileShare.None, 4096, useAsync: true))
    {
      await Request.Context.CopyToAsync(fs);
    }
    return Ok();
  }
  catch (Exception ex)
  {
    return BadRequest("ERROR: Audio could not be saved on server.");
  }
}