DelegatingHandler解压缩WebApi中的传入请求 [英] DelegatingHandler to decompress incoming requests in WebApi
问题描述
在我的应用中,我们正在从客户端发送大小合适的数据包,并收到大小合适的响应,因此我想在向上和向后执行一些压缩。
In my app we are sending decent size packets up from a client and receiving a decent sized response, so I want to implement some compression on the way up and the way back.
回来的时候很好,因为我可以依靠IIS的动态压缩为我做这件事,但是在上升的过程中,我发现了以下问题。
On the way back it is fine because I can lean on IIS's dynamic compression to do that for me, but on the way up I am finding the following issue.
我有一个委托处理程序,用于解压缩传入的请求:
(大多数代码基于Fabrik.Common的各个部分( https://github.com/benfoster/Fabrik.Common )))
I have a delegating handler that sits there to decompress the incoming requests: (Most of this code is based on parts of Fabrik.Common (https://github.com/benfoster/Fabrik.Common))
public class DecompressionHandler : DelegatingHandler
{
public Collection<ICompressor> Compressors;
public DecompressionHandler()
{
Compressors = new Collection<ICompressor> {new GZipCompressor(), new DeflateCompressor()};
}
protected async override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
{
if (request.Content.Headers.ContentEncoding.IsntNullOrEmpty() && request.Content != null)
{
var encoding = request.Content.Headers.ContentEncoding.First();
var compressor = Compressors.FirstOrDefault(c => c.EncodingType.Equals(encoding, StringComparison.InvariantCultureIgnoreCase));
if (compressor != null)
{
request.Content = await DecompressContentAsync(request.Content, compressor).ConfigureAwait(true);
}
}
var response = await base.SendAsync(request, cancellationToken).ConfigureAwait(true);
return response;
}
private static async Task<HttpContent> DecompressContentAsync(HttpContent compressedContent, ICompressor compressor)
{
using (compressedContent)
{
var decompressed = new MemoryStream();
await compressor.Decompress(await compressedContent.ReadAsStreamAsync(), decompressed).ConfigureAwait(true);
// set position back to 0 so it can be read again
decompressed.Position = 0;
var newContent = new StreamContent(decompressed);
// copy content type so we know how to load correct formatter
newContent.Headers.ContentType = compressedContent.Headers.ContentType;
return newContent;
}
}
}
public class DeflateCompressor : Compressor
{
private const string DeflateEncoding = "deflate";
public override string EncodingType
{
get { return DeflateEncoding; }
}
public override Stream CreateCompressionStream(Stream output)
{
return new DeflateStream(output, CompressionMode.Compress, leaveOpen: true);
}
public override Stream CreateDecompressionStream(Stream input)
{
return new DeflateStream(input, CompressionMode.Decompress, leaveOpen: true);
}
}
public abstract class Compressor : ICompressor
{
public abstract string EncodingType { get; }
public abstract Stream CreateCompressionStream(Stream output);
public abstract Stream CreateDecompressionStream(Stream input);
public virtual Task Compress(Stream source, Stream destination)
{
var compressed = CreateCompressionStream(destination);
return Pump(source, compressed)
.ContinueWith(task => compressed.Dispose());
}
public virtual Task Decompress(Stream source, Stream destination)
{
var decompressed = CreateDecompressionStream(source);
return Pump(decompressed, destination)
.ContinueWith(task => decompressed.Dispose());
}
protected virtual Task Pump(Stream input, Stream output)
{
return input.CopyToAsync(output);
}
}
public interface ICompressor
{
string EncodingType { get; }
Task Compress(Stream source, Stream destination);
Task Decompress(Stream source, Stream destination);
}
public class GZipCompressor : Compressor
{
private const string GZipEncoding = "gzip";
public override string EncodingType
{
get { return GZipEncoding; }
}
public override Stream CreateCompressionStream(Stream output)
{
return new GZipStream(output, CompressionMode.Compress, leaveOpen: true);
}
public override Stream CreateDecompressionStream(Stream input)
{
return new GZipStream(input, CompressionMode.Decompress, leaveOpen: true);
}
}
减压工作正常,我有我的要求。
The decompression works fine and I have my request.Content populated with a result that is my decompressed JSON.
当我将其传递给base.SendAsync并到达我的控制器方法时,该模型为null,而在实现之前
When I pass that off to base.SendAsync and it hits my controller method, the model is null, whereas before I implemented compression it was all working great.
我已经读到,当您阅读进来的内容流时,这是一次性的事情,但是我认为设置request.content
I have read that when you Read the content stream coming in that it is a once off thing, but I thought setting the request.content to the decompressed result should let it be read again?
推荐答案
我解决了这个问题。
这是我的HTTPClient实现中的一个错误,我从使用PostAsJsonAsync移到PostAsync来执行压缩客户端,但是没有添加Content-Type标头来指定application / json。
It was an error in my HTTPClient implementation where I had moved from using PostAsJsonAsync to PostAsync to do the compression client side, but had not added the Content-Type header to specify application/json.
在客户端执行完此操作后,一切都按计划进行。
After doing that in the client, all is working as planned.
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