在我的应用程序中,我们从客户端向上发送大小合适的数据包并接收大小合适的响应,因此我想在向上和返回的过程中实现一些压缩。
在回来的路上很好,因为我可以依靠 IIS 的动态压缩来为我做这件事,但是在回来的路上我发现了以下问题。
我有一个委托处理程序来解压缩传入的请求:(大部分代码基于 Fabrik.Common 的部分(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);
}
}
解压缩工作正常,我的 request.Content 填充了我解压缩的 JSON 的结果。
当我将它传递给 base.SendAsync 并命中我的控制器方法时,模型为空,而在我实施压缩之前,它一切正常。
我已经读过,当您阅读传入的内容流时,它是一次性的,但我认为将 request.content 设置为解压缩结果应该让它再次被读取?