• ASP.NET 首页性能的4大做法


    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。(阿会楠,现在采用MVC或者其他方法已经可以有效杜绝ViewState的生成了)

    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:

    复制代码
    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 ) );
    }
    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" );
    来源:v5软件网(http://www.v5soft.com
    [详细地址]:http://www.v5soft.com/html/news/view/2011/03-17/341.html

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  • 原文地址:https://www.cnblogs.com/sntetwt/p/1995757.html
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