处理 ASP.NET Core 1.0 上的大文件上传
当我在 ASP.NET Core 中将大文件上传到我的 web api 时，运行时会将文件加载到内存中，然后我的用于处理和存储上传的函数被触发.对于大型上传，这会成为一个问题，因为它既慢又需要更多内存.对于以前版本的 ASP.NET 有一些关于如何禁用请求缓冲的文章，但我找不到有关如何使用 ASP.NET Core 执行此操作的任何信息.是否可以禁用请求缓冲，这样我的服务器内存不会一直用完?
When I'm uploading large files to my web api in ASP.NET Core, the runtime will load the file into memory before my function for processing and storing the upload is fired. With large uploads this becomes an issue as it is both slow and requires more memory. For previous versions of ASP.NET there are some articles on how to disable the buffering of requests, but I'm not able to find any information on how to do this with ASP.NET Core. Is it possible to disable the buffering of requests so I don't run out of memory on my server all the time?
使用 Microsoft.AspNetCore.WebUtilities.MultipartReader 因为它...
可以用最少的缓冲解析任何流.它一次为您提供每个部分的标题和正文，然后您可以对该部分的正文执行您想要的操作(缓冲、丢弃、写入磁盘等).
can parse any stream [with] minimal buffering. It gives you the headers and body of each section one at a time and then you do what you want with the body of that section (buffer, discard, write to disk, etc.).
这是一个中间件示例.
app.Use(async (context, next) =>
{
if (!IsMultipartContentType(context.Request.ContentType))
{
await next();
return;
}
var boundary = GetBoundary(context.Request.ContentType);
var reader = new MultipartReader(boundary, context.Request.Body);
var section = await reader.ReadNextSectionAsync();
while (section != null)
{
// process each image
const int chunkSize = 1024;
var buffer = new byte[chunkSize];
var bytesRead = 0;
var fileName = GetFileName(section.ContentDisposition);
using (var stream = new FileStream(fileName, FileMode.Append))
{
do
{
bytesRead = await section.Body.ReadAsync(buffer, 0, buffer.Length);
stream.Write(buffer, 0, bytesRead);
} while (bytesRead > 0);
}
section = await reader.ReadNextSectionAsync();
}
context.Response.WriteAsync("Done.");
});
这里是帮手.
private static bool IsMultipartContentType(string contentType)
{
return
!string.IsNullOrEmpty(contentType) &&
contentType.IndexOf("multipart/", StringComparison.OrdinalIgnoreCase) >= 0;
}
private static string GetBoundary(string contentType)
{
var elements = contentType.Split(' ');
var element = elements.Where(entry => entry.StartsWith("boundary=")).First();
var boundary = element.Substring("boundary=".Length);
// Remove quotes
if (boundary.Length >= 2 && boundary[0] == '"' &&
boundary[boundary.Length - 1] == '"')
{
boundary = boundary.Substring(1, boundary.Length - 2);
}
return boundary;
}
private string GetFileName(string contentDisposition)
{
return contentDisposition
.Split(';')
.SingleOrDefault(part => part.Contains("filename"))
.Split('=')
.Last()
.Trim('"');
}
外部参考