压缩 HTTP GET 响应 [英] Compress HTTP GET Response

问题描述

我目前正在将我的几个 MVC3 控制器迁移到 MVC4 Api 控制器.我已经通过继承 ActionFilterAttribute 和覆盖 OnActionExecutiong 方法实现了 MVC3 控制器获取方法响应的压缩机制.经过一些研究，我发现我需要使用 System.Web.HttpFilters 中的 ActionFilterMethod.如果有人可以分享一段示例代码让我开始使用 GZip 压缩 HTTP 响应，那就太好了

I am currently working on migrating few of my MVC3 Controllers to MVC4 Api Controllers. I have implemented Compression mechanism for MVC3 controller Get Method Responses by inherting ActionFilterAttribute and overriding OnActionExecutiong method. After some Research I found that I need to use ActionFilterMethod from System.Web.HttpFilters. It would be great if somebody can share piece of sample code to get me started for this compressing HTTP response using GZip

推荐答案

最简单的是启用压缩 直接在 IIS 级别.

The easiest is to enable compression directly at IIS level.

如果您想在应用程序级别执行此操作，您可以编写一个自定义的委托消息处理程序，如以下所示发帖:

If you want to do it at the application level you could write a custom delegating message handler as shown in the following post:

public class CompressHandler : DelegatingHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        return base.SendAsync(request, cancellationToken).ContinueWith<HttpResponseMessage>((responseToCompleteTask) =>
        {
            HttpResponseMessage response = responseToCompleteTask.Result;

            if (response.RequestMessage.Headers.AcceptEncoding != null)
            {
                string encodingType = response.RequestMessage.Headers.AcceptEncoding.First().Value;

                response.Content = new CompressedContent(response.Content, encodingType);
            }

            return response;
        },
        TaskContinuationOptions.OnlyOnRanToCompletion);
    }
}

public class CompressedContent : HttpContent
{
    private HttpContent originalContent;
    private string encodingType;

    public CompressedContent(HttpContent content, string encodingType)
    {
        if (content == null)
        {
            throw new ArgumentNullException("content");
        }

        if (encodingType == null)
        {
            throw new ArgumentNullException("encodingType");
        }

        originalContent = content;
        this.encodingType = encodingType.ToLowerInvariant();

        if (this.encodingType != "gzip" && this.encodingType != "deflate")
        {
            throw new InvalidOperationException(string.Format("Encoding '{0}' is not supported. Only supports gzip or deflate encoding.", this.encodingType));
        }

        // copy the headers from the original content
        foreach (KeyValuePair<string, IEnumerable<string>> header in originalContent.Headers)
        {
            this.Headers.AddWithoutValidation(header.Key, header.Value);
        }

        this.Headers.ContentEncoding.Add(encodingType);
    }

    protected override bool TryComputeLength(out long length)
    {
        length = -1;

        return false;
    }

    protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
    {
        Stream compressedStream = null;

        if (encodingType == "gzip")
        {
            compressedStream = new GZipStream(stream, CompressionMode.Compress, leaveOpen: true);
        }
        else if (encodingType == "deflate")
        {
            compressedStream = new DeflateStream(stream, CompressionMode.Compress, leaveOpen: true);
        }

        return originalContent.CopyToAsync(compressedStream).ContinueWith(tsk =>
        {
            if (compressedStream != null)
            {
                compressedStream.Dispose();
            }
        });
    }
}

现在剩下的就是在Application_Start中注册处理程序:

All that's left now is to register the handler in Application_Start:

GlobalConfiguration.Configuration.MessageHandlers.Add(new CompressHandler());

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