流大文件（大于2GB过IIS）使用的WebAPI [英] Streaming large files (>2GB over IIS) using WebAPI
问题描述
我要上传非常大的文件（> 2GB）我的WebAPI应用程序（在.NET运行4.5.2的Windows 2012R2）。
设置的httpRuntime maxRequestLength的属性是没有用的，因为它只有小于2GB的文件工作。
我目前使用的自定义MultipartFormDataStreamProvider读取服务器上的整个流，我已经使用自定义WebHostBufferPolicySelector已经关闭缓冲。
我发现的是，ASP.NET（或的WebAPI为此事）使用HttpBufferlessInputStream其中有一个叫_disableMaxRequestLength领域的引擎盖下。如果我这个值设置为为true（通过反射），我可以流的任何大小的文件。
然而，围绕这些摆弄这些internas显然不是一个好办法。
用于请求的Htt prequest类有一个叫做的 GetBufferlessInputStream 具有过载，使禁用的maxRequestLength。
我的问题是：我怎样才能获得的WebAPI，而不是使用标准之一，这个重载
？有什么办法来替代默认的Htt prequest或HttpContext类？或者我真的需要使用反射整个东西？
这是我目前使用禁用的maxRequestLength的code：
私人无效DisableRequestLengthOnStream（HttpContent父）
{
。VAR streamContentProperty = parent.GetType（）的getProperty（StreamContent，BindingFlags.Instance | BindingFlags.NonPublic可| BindingFlags.Public）;
如果（streamContentProperty == NULL）回报;
VAR streamContent = streamContentProperty.GetValue（父母，NULL）;
如果（streamContent == NULL）回报;
VAR contentProperty = typeof运算（StreamContent）.GetField（内容，BindingFlags.Instance | BindingFlags.NonPublic可）;
如果（contentProperty == NULL）回报;
VAR内容= contentProperty.GetValue（streamContent）;
如果（内容== NULL）回报;
VAR requestLengthField = content.GetType（）getfield命令（_ disableMaxRequestLength，BindingFlags.Instance | BindingFlags.NonPublic可）。
如果（requestLengthField == NULL）回报;
requestLengthField.SetValue（内容，真实）;
}
好吧，我发现了一个pretty简单的解决方案。从@JustinR答案。会的工作，当然。但我想继续，因为处理所有的MIME东西使用MultipartFormDataStreamProvider。
解决方案是简单地创建一个新的StreamContent实例与正确的无缓冲输入流，并与原来的内容标题来填充它：
VAR提供商=新MultipartFormDataStreamProvider（路径）;
VAR内容=新StreamContent（HttpContext.Current.Request.GetBufferlessInputStream（真））;
的foreach（在Request.Content.Headers VAR头）
{
content.Headers.TryAddWithoutValidation（header.Key，header.Value）;
} 等待content.ReadAsMultipartAsync（供应商）;
I'm trying to upload very large files (>2GB) to my WebAPI application (Running on .NET 4.5.2, Windows 2012R2).
Setting the httpRuntime maxRequestLength property is of no use because it's only working with files smaller than 2GB.
I'm currently using a custom MultipartFormDataStreamProvider to read the entire stream on the Server and I've already turned off buffering using a custom WebHostBufferPolicySelector.
What I discovered is that ASP.NET (or WebAPI for that matter) uses a HttpBufferlessInputStream under the Hood which has a field called _disableMaxRequestLength. If I set this value to to true (via reflection), I can stream files of any size.
However, fiddling around these with these internas is clearly not a good way.
The HttpRequest class used for the request has a method called GetBufferlessInputStream which has an overload that allows to disable the maxRequestLength.
My question is: How can I get the WebAPI to use this overload instead of the Standard one?
Is there any way to replace the Default HttpRequest or HttpContext class? Or do I really Need to use reflection for the whole stuff?
This is the code I'm currently using to disable the maxRequestLength:
private void DisableRequestLengthOnStream(HttpContent parent)
{
var streamContentProperty = parent.GetType().GetProperty("StreamContent", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
if (streamContentProperty == null) return;
var streamContent = streamContentProperty.GetValue(parent, null);
if (streamContent == null) return;
var contentProperty = typeof(StreamContent).GetField("content", BindingFlags.Instance | BindingFlags.NonPublic);
if (contentProperty == null) return;
var content = contentProperty.GetValue(streamContent);
if (content == null) return;
var requestLengthField = content.GetType().GetField("_disableMaxRequestLength", BindingFlags.Instance | BindingFlags.NonPublic);
if (requestLengthField == null) return;
requestLengthField.SetValue(content, true);
}
Ok, I found a pretty simple solution. The answer from @JustinR. would work, of course. But I wanted to continue to use a MultipartFormDataStreamProvider because that handles all the MIME stuff.
The solution is to simply create a new StreamContent instance with the correct bufferless Input stream and populate it with the headers from the original Content:
var provider = new MultipartFormDataStreamProvider(path);
var content = new StreamContent(HttpContext.Current.Request.GetBufferlessInputStream(true));
foreach (var header in Request.Content.Headers)
{
content.Headers.TryAddWithoutValidation(header.Key, header.Value);
}
await content.ReadAsMultipartAsync(provider);
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