Asp.net使用HttpModule压缩并删除空白Html请求

       当我们压缩我的Response后再传到Client端时,可以明显节省宽带. 提升Site的性能. 现在的浏览器大部分都支持Gzip,Deflate压缩. 同时我们还可以删除一些空白
段,空行,注释等以使得HTML文档的尺寸变得更小. 让我们先来实现压缩与删除空白类, 继承自Stream类:

    /// <summary>
    /// CompressWhitespaceFilter
    /// </summary>
    public class CompressWhitespaceFilter : Stream
    {
        private GZipStream _contentGZipStream;
        private DeflateStream _content_DeflateStream;
        private Stream _contentStream;
        private CompressOptions _compressOptions;


        /// <summary>
        /// Initializes a new instance of the <see cref="CompressWhitespaceFilter"/> class.
        /// </summary>
        /// <param name="contentStream">The content stream.</param>
        /// <param name="compressOptions">The compress options.</param>
        public CompressWhitespaceFilter(Stream contentStream, CompressOptions compressOptions)
        {
            if (compressOptions == CompressOptions.GZip)
            {
                this._contentGZipStream = new GZipStream(contentStream, CompressionMode.Compress);
                this._contentStream = this._contentGZipStream;
            }
            else if (compressOptions == CompressOptions.Deflate)
            {
                this._content_DeflateStream = new DeflateStream(contentStream,CompressionMode.Compress);
                this._contentStream = this._content_DeflateStream;
            }
            else
            {
                this._contentStream = contentStream;
            }
            this._compressOptions = compressOptions;
        }

        public override bool CanRead
        {
            get { return this._contentStream.CanRead; }
        }

        public override bool CanSeek
        {
            get { return this._contentStream.CanSeek; }
        }

        public override bool CanWrite
        {
            get { return this._contentStream.CanWrite; }
        }

        public override void Flush()
        {
            this._contentStream.Flush();
        }

        public override long Length
        {
            get { return this._contentStream.Length; }
        }

        public override long Position
        {
            get
            {
                return this._contentStream.Position;
            }
            set
            {
                this._contentStream.Position = value;
            }
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            return this._contentStream.Read(buffer, offset, count);
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            return this._contentStream.Seek(offset, origin);
        }

        public override void SetLength(long value)
        {
            this._contentStream.SetLength(value);
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            byte[] data = new byte[count + 1];
            Buffer.BlockCopy(buffer, offset, data, 0, count);

            string strtext = System.Text.Encoding.UTF8.GetString(data);
            strtext = Regex.Replace(strtext, "^\\s*", string.Empty, RegexOptions.Compiled | RegexOptions.Multiline);
            strtext = Regex.Replace(strtext, "\\r\\n", string.Empty, RegexOptions.Compiled | RegexOptions.Multiline);
            strtext = Regex.Replace(strtext, "<!--*.*?-->", string.Empty, RegexOptions.Compiled | RegexOptions.Multiline);

            byte[] outdata = System.Text.Encoding.UTF8.GetBytes(strtext);
            this._contentStream.Write(outdata, 0, outdata.GetLength(0));
        }
    }

    /// <summary>
    /// CompressOptions
    /// </summary>
    /// <seealso cref="http://en.wikipedia.org/wiki/Zcat#gunzip_and_zcat"/>
    /// <seealso cref="http://en.wikipedia.org/wiki/DEFLATE"/>
    public enum CompressOptions
    {
        GZip,
        Deflate,
        None
    }

       上面的代码使用正则表达式替换字符串,你可以修改那些正则表达式来满足你的需求. 我们同时使用了GZipStream与DeflateStream实现了压缩. 好的,接下来与
HttpModule结合:

    /// <summary>
    /// CompressWhitespaceModule
    /// </summary>
    public class CompressWhitespaceModule : IHttpModule
    {
        #region IHttpModule Members

        /// <summary>
        /// Disposes of the resources (other than memory) used by the module that implements <see cref="T:System.Web.IHttpModule"/>.
        /// </summary>
        public void Dispose()
        {
            // Nothing to dispose;
        }

        /// <summary>
        /// Initializes a module and prepares it to handle requests.
        /// </summary>
        /// <param name="context">An <see cref="T:System.Web.HttpApplication"/> that provides access to the methods, properties, and events common to all application objects within an ASP.NET application</param>
        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(context_BeginRequest);
        }

        /// <summary>
        /// Handles the BeginRequest event of the context control.
        /// </summary>
        /// <param name="sender">The source of the event.</param>
        /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
        void context_BeginRequest(object sender, EventArgs e)
        {
            HttpApplication app = sender as HttpApplication;
            if (app.Request.RawUrl.Contains(".aspx"))
            {
                HttpContext context = app.Context;
                HttpRequest request = context.Request;
                string acceptEncoding = request.Headers["Accept-Encoding"];
                HttpResponse response = context.Response;
                if (!string.IsNullOrEmpty(acceptEncoding))
                {
                    acceptEncoding = acceptEncoding.ToUpperInvariant();
                    if (acceptEncoding.Contains("GZIP"))
                    {
                        response.Filter = new CompressWhitespaceFilter(context.Response.Filter, CompressOptions.GZip);
                        response.AppendHeader("Content-encoding", "gzip");
                    }
                    else if (acceptEncoding.Contains("DEFLATE"))
                    {
                        response.Filter = new CompressWhitespaceFilter(context.Response.Filter, CompressOptions.Deflate);
                        response.AppendHeader("Content-encoding", "deflate");
                    }
                }
                response.Cache.VaryByHeaders["Accept-Encoding"] = true;
            }
        }

        #endregion
    }

HttpApplication.BeginRequest 事件是 在 ASP.NET 响应请求时作为 HTTP 执行管线链中的第一个事件发生。

在WEB.CONFIG中你还需要配置:

<httpModules>
  <add name="CompressWhitespaceModule"  type="MyWeb.CompressWhitespaceModule" />
</httpModules>

我们来看一下效果,下面没有使用时, 4.8KB

接着看,处理过后的效果,Cotent-Encoding: gzip,  filezie: 1.6KB

很简单,你可以按需求来增加更多的功能. 希望对您开发有帮助.

作者：Petter Liu
出处：http://www.cnblogs.com/wintersun/
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
该文章也同时发布在我的独立博客中-Petter Liu Blog。