Asp.net使用HttpModule压缩并删除空白Html请求的实现代码

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:


代码如下:

/// <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:


代码如下:

/// <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:


代码如下:

<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