其实找了好久关于提高asp.net首页性能的文章了,大多是讲将aspx网页静态化的方法,今天才看到这篇文章,相见恨晚...不过还是有些不明白的地方,先转载过来,然后再慢慢咀嚼下~

原文链接:http://www.cnblogs.com/cnshangsha/archive/2010/05/06/Ten_practices_aspnet_performance.html

 

前言
本文是我对ASP.NET页面载入速度提高的一些做法,这些做法分为以下部分:
 
针对上述做法,我们首先需要一个 HTTP 模块,它是整个页面流程的入口和核心。
 
一、自定义Response.Filter得到输出流stream生成动态页面的静态内容(磁盘缓存)
如下的代码我们可以看出,我们以 request.RawUrl 为缓存基础,因为它可以包含任意的QueryString变量,然后我们用MD5加密RawUrl 得到服务器本地文件名的变量,再实例化一个FileInfo操作该文件,如果文件最后一次生成时间小于7天,我们就使用.Net2.0新增的TransmitFile方法将存储文件的静态内容发送到浏览器。如果文件不存在,我们就操作 response.Filter 得到的 Stream 传递给 CommonFilter 类,并利用FileStream写入动态页面的内容到静态文件中。
namespace  ASPNET_CL.Code.HttpModules {
     public  class  CommonModule : IHttpModule {
         public  void  Init( HttpApplication application ) {
            application.BeginRequest += Application_BeginRequest;
        }

         private  void  Application_BeginRequest(  object  sender, EventArgs e ) {
            var context = HttpContext.Current;
            var request = context.Request;
            var url = request.RawUrl;

            var response = context.Response;
            var path = GetPath( url );
            var file =  new  FileInfo( path );

             if  ( DateTime.Now.Subtract( file.LastWriteTime ).TotalDays < 7 ) {
                response.TransmitFile( path );
                response.End();
                 return;
            }
             try  {
                var stream = file.OpenWrite();
                response.Filter =  new  CommonFilter( response.Filter, stream );
            }
             catch  ( Exception ) {
                 //Log.Insert("");
            }
        }

         public  void  Dispose() {

        }

         private  static  string  GetPath(  string  url ) {
            var hash = Hash( url );
             string  fold = HttpContext.Current.Server.MapPath(  "~/Temp/"  );
             return  string.Concat( fold, hash );
        }

         private  static  string  Hash(  string  url ) {
            url = url.ToUpperInvariant();
            var md5 =  new  System.Security.Cryptography.MD5CryptoServiceProvider();
            var bs = md5.ComputeHash( Encoding.ASCII.GetBytes( url ) );
            var s =  new  StringBuilder();
             foreach  ( var b  in  bs ) {
                s.Append( b.ToString(  "x2"  ).ToLower() );
            }
             return  s.ToString();
        }
    }
}
 
二、页面GZIP压缩
对页面GZIP压缩几乎是每篇讲解高性能WEB程序的几大做法之一,因为使用GZIP压缩可以降低服务器发送的字节数,能让客户感觉到网页的速度更快也减少了对带宽的使用情况。当然,这里也存在客户端的浏览器是否支持它。因此,我们要做的是,如果客户端支持GZIP,我们就发送GZIP压缩过的内容,如果不支持,我们直接发送静态文件的内容。幸运的是,现代浏览器IE6.7.8.0,火狐等都支持GZIP。
为了实现这个功能,我们需要改写上面的 Application_BeginRequest 事件:
         private void Application_BeginRequest( object sender, EventArgs e ) {
            var context = HttpContext.Current;
            var request = context.Request;
            var url = request.RawUrl;

            var response = context.Response;
            var path = GetPath( url );
            var file = new FileInfo( path );

            // 使用页面压缩
              ResponseCompressionType compressionType = this.GetCompressionMode( request );
            if ( compressionType != ResponseCompressionType.None ) {
                response.AppendHeader( "Content-Encoding", compressionType.ToString().ToLower() );
                if ( compressionType == ResponseCompressionType.GZip ) {
                    response.Filter = new GZipStream( response.Filter, CompressionMode.Compress );
                }
                else {
                    response.Filter = new DeflateStream( response.Filter, CompressionMode.Compress );
                }
            }

            if ( DateTime.Now.Subtract( file.LastWriteTime ).TotalMinutes < 5 ) {
                response.TransmitFile( path );
                response.End();
                return;
            }
            try {
                var stream = file.OpenWrite();
                response.Filter = new CommonFilter( response.Filter, stream );
            }
            catch ( Exception ) {
                //Log.Insert("");
            }
        }

        private ResponseCompressionType GetCompressionMode( HttpRequest request ) {
            string acceptEncoding = request.Headers[ "Accept-Encoding" ];
            if ( string.IsNullOrEmpty( acceptEncoding ) )
                return ResponseCompressionType.None;

            acceptEncoding = acceptEncoding.ToUpperInvariant();

            if ( acceptEncoding.Contains( "GZIP" ) )
                return ResponseCompressionType.GZip;
            else if ( acceptEncoding.Contains( "DEFLATE" ) )
                return ResponseCompressionType.Deflate;
            else
                return ResponseCompressionType.None;
        }

        private enum ResponseCompressionType {
            None,
            GZip,
            Deflate
        }
三、OutputCache 编程方式输出页面缓存
ASP.NET内置的 OutputCache 缓存可以将内容缓存在三个地方:Web服务器、代理服务器和浏览器。当用户访问一个被设置为 OutputCache的页面时,ASP.NET在MSIL之后,先将结果写入output cache缓存,然后在发送到浏览器,当用户访问同一路径的页面时,ASP.NET将直接发送被Cache的内容,而不经过.aspx编译以及执行MSIL的过程,所以,虽然程序的本身效率没有提升,但是页面载入速度却得到了提升。
 
为了实现这个功能,我们继续改写上面的 Application_BeginRequest 事件,我们在 TransmitFile 后,将这个路径的页面以OutputCache编程的方式缓存起来:
 private void Application_BeginRequest( object sender, EventArgs e ) {
         
           //.............

            if ( DateTime.Now.Subtract( file.LastWriteTime ).TotalMinutes < 5 ) {
                response.TransmitFile( path );
                // 添加 OutputCache 缓存头,并缓存在客户端
                  response.Cache.SetExpires( DateTime.Now.AddMinutes( 5 ) );
                response.Cache.SetCacheability( HttpCacheability.Public );
                response.End();
                return;
            }
           
           //............
 }
 
四、实现CommonFilter类过滤ViewState、过滤NamingContainer、空白字符串,以及生成磁盘的缓存文件
我们传入response.Filter的Stream对象给CommonFilter类:
首先,我们用先Stream的Write方法实现生成磁盘的缓存文件,代码如下,在这些代码中,只有初始化构造函数,Write方法,Close方式是有用的,其中FileStream字段是生成静态文件的操作对象:
namespace ASPNET_CL.Code.HttpModules {
    public class CommonFilter : Stream {
        private readonly Stream _responseStream;
        private readonly FileStream _cacheStream;

        public override bool CanRead {
            get {
                return false;
            }
        }
        public override bool CanSeek {
            get {
                return false;
            }
        }
        public override bool CanWrite {
            get {
                return _responseStream.CanWrite;
            }
        }
        public override long Length {
            get {
                throw new NotSupportedException();
            }
        }
        public override long Position {
            get {
                throw new NotSupportedException();
            }
            set {
                throw new NotSupportedException();
            }
        }

        public CommonFilter( Stream responseStream, FileStream stream ) {
            _responseStream = responseStream;
            _cacheStream = stream;
        }

        public override long Seek( long offset, SeekOrigin origin ) {
            throw new NotSupportedException();
        }
        public override void SetLength( long length ) {
            throw new NotSupportedException();
        }
        public override int Read( byte[] buffer, int offset, int count ) {
            throw new NotSupportedException();
        }
        public override void Flush() {
            _responseStream.Flush();
            _cacheStream.Flush();
        }
        public override void Write( byte[] buffer, int offset, int count ) {
            _cacheStream.Write( buffer, offset, count );
            _responseStream.Write( buffer, offset, count );
        }
        public override void Close() {
            _responseStream.Close();
            _cacheStream.Close();
        }
        protected override void Dispose( bool disposing ) {
            if ( disposing ) {
                _responseStream.Dispose();
                _cacheStream.Dispose();
            }
        }
    }

}
 
然后我们利用正则完全删除ViewState:
        // 过滤ViewState
        private string ViewStateFilter( string strHTML ) {
            string matchString1 = "type=\"hidden\" name=\"__VIEWSTATE\" id=\"__VIEWSTATE\"";
            string matchString2 = "type=\"hidden\" name=\"__EVENTVALIDATION\" id=\"__EVENTVALIDATION\"";
            string matchString3 = "type=\"hidden\" name=\"__EVENTTARGET\" id=\"__EVENTTARGET\"";
            string matchString4 = "type=\"hidden\" name=\"__EVENTARGUMENT\" id=\"__EVENTARGUMENT\"";

            string positiveLookahead1 = "(?=.*(" + Regex.Escape( matchString1 ) + "))";
            string positiveLookahead2 = "(?=.*(" + Regex.Escape( matchString2 ) + "))";
            string positiveLookahead3 = "(?=.*(" + Regex.Escape( matchString3 ) + "))";
            string positiveLookahead4 = "(?=.*(" + Regex.Escape( matchString4 ) + "))";

            RegexOptions opt = RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.CultureInvariant | RegexOptions.Compiled;

            Regex[] arrRe = new Regex[] {
                new Regex("\\s*<div>" + positiveLookahead1 + "(.*?)</div>\\s*", opt),
                new Regex("\\s*<div>" + positiveLookahead2 + "(.*?)</div>\\s*", opt),
                new Regex("\\s*<div>" + positiveLookahead3 + "(.*?)</div>\\s*", opt),
                new Regex("\\s*<div>" + positiveLookahead3 + "(.*?)</div>\\s*", opt),
                new Regex("\\s*<div>" + positiveLookahead4 + "(.*?)</div>\\s*", opt)
            };

            foreach ( Regex re in arrRe ) {
                strHTML = re.Replace( strHTML, "" );
            }

            return strHTML;
        }
以下是删除页面空白的方法:
        // 删除空白
         private Regex tabsRe = new Regex( "\\t", RegexOptions.Compiled | RegexOptions.Multiline );
        private Regex carriageReturnRe = new Regex( ">\\r\\n<", RegexOptions.Compiled | RegexOptions.Multiline );
        private Regex carriageReturnSafeRe = new Regex( "\\r\\n", RegexOptions.Compiled | RegexOptions.Multiline );
        private Regex multipleSpaces = new Regex( "  ", RegexOptions.Compiled | RegexOptions.Multiline );
        private Regex spaceBetweenTags = new Regex( ">\\s<", RegexOptions.Compiled | RegexOptions.Multiline );
        private string WhitespaceFilter( string html ) {
            html = tabsRe.Replace( html, string.Empty );
            html = carriageReturnRe.Replace( html, "><" );
            html = carriageReturnSafeRe.Replace( html, " " );

            while ( multipleSpaces.IsMatch( html ) )
                html = multipleSpaces.Replace( html, " " );

            html = spaceBetweenTags.Replace( html, "><" );

            html = html.Replace( "//<![CDATA[", "" );
            html = html.Replace( "//]]>", "" );

            return html;
        }
以下是删除ASP.NET控件的垃圾UniqueID名称方法:
        // 过滤NamingContainer
        private string NamingContainerFilter( string html ) {
            RegexOptions opt =
                RegexOptions.IgnoreCase |
                RegexOptions.Singleline |
                RegexOptions.CultureInvariant |
                RegexOptions.Compiled;

            Regex re = new Regex( "( name=\")(?=.*(" + Regex.Escape( "$" ) + "))([^\"]+?)(\")", opt );

            html = re.Replace( html, new MatchEvaluator( delegate( Match m ) {
                int lastDollarSignIndex = m.Value.LastIndexOf( '$' );

                if ( lastDollarSignIndex >= 0 ) {
                    return m.Groups[ 1 ].Value + m.Value.Substring( lastDollarSignIndex + 1 );
                }
                else {
                    return m.Value;
                }
            } ) );

            return html;
        }
最后,我们把以上过滤方法整合到CommonFilter类的Write方法:
        public override void Write( byte[] buffer, int offset, int count ) {
            // 转换buffer为字符串
            byte[] data = new byte[ count ];
            Buffer.BlockCopy( buffer, offset, data, 0, count );
            string html = System.Text.Encoding.UTF8.GetString( buffer );

            //
            // 以下整合过滤方法
             //

            html = NamingContainerFilter( html );
            html = ViewStateFilter( html );
            html = WhitespaceFilter( html );

            byte[] outdata = System.Text.Encoding.UTF8.GetBytes( html );

            // 写入磁盘
            _cacheStream.Write( outdata, 0, outdata.GetLength( 0 ) );
            _responseStream.Write( outdata, 0, outdata.GetLength( 0 ) );
        }
 
五、缓存破坏
经过以上程序的实现,网页已经被高速缓存在客户端了,如果果用户访问网站被缓存过的页面,则页面会以0请求的速度加载页面。但是,如果后台更新了某些数据,前台用户则不能及时看到最新的数据,因此要改变这种情况,我们必须破坏缓存。根据我们如上的程序,我们破坏缓存只需要做2步:更新服务器上的临时文件,删除OutputCache过的页面。
 
更新服务器上的文件我们只需删除这个文件即可,当某一用户第一次访问该页面时会自动生成,当然,你也可以用程序先删除后生成:
            // 更新文件
            foreach ( var file in Directory.GetFiles( HttpRuntime.AppDomainAppPath + "Temp" ) ) {
                File.Delete( file );
            }

要删除OutputCache关联的缓存项,代码如下,我们只需要保证该方法的参数,指页面的绝对路径是正确的,路径不能使用../这样的相对路径:

            // 删除缓存
            HttpResponse.RemoveOutputCacheItem( "/Default.aspx" );
到此,我们实现了针对一个页面的性能,重点是载入速度的提高的一些做法,希望对大家有用~!