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