Asp.net HTTP处理程序和动态CSS生成

本文关键字：动态 CSS 生成 程序 net HTTP 处理 Asp | 更新日期: 2023-09-27 18:18:19

我正在编写一个http处理程序，它将加载一个文件(css模板)修改它的内容，并将其作为text/css提供。

我的代码基于我在这里找到的一个例子:

http://madskristensen.net/post/Remove-whitespace-from-stylesheets-and-JavaScript-files.aspx

代码的业务部分是:

public void ProcessRequest(HttpContext context)
{
    try
    {
        string file = context.Request.PhysicalPath;
        if (!File.Exists(file))
            return;
        string body = string.Empty;
        if (context.Cache[CSS_CACHE_BODY + file] != null)
            body = context.Cache[CSS_CACHE_BODY + file].ToString();
       if (body == string.Empty)
        {
            StreamReader reader = new StreamReader(file);
            body = reader.ReadToEnd();
            reader.Close();
            // Modify css template here
            CacheDependency cd = new CacheDependency(file);
            context.Cache.Insert(CSS_CACHE_BODY + file, body, cd);
        }
        context.Response.ContentType = "text/css";
        context.Response.Write(body);
    }
    catch (Exception ex)
    {
        context.Response.Write(ex.Message);
    }
}

如果人们能评论一下这段代码的效率和健壮性，我将不胜感激。我宁愿不要等到生产环境才发现任何问题!

Asp.net HTTP处理程序和动态CSS生成

有一些性能提示，您可以缓存响应客户端(使用HTTP报头)。此外，在发送响应之前，您可以对输出使用空白清除方法。另一点是压缩:如果浏览器支持，就压缩响应。

客户端缓存示例(在VB中): 
        Dim incomingEtag As String = context.Request.Headers("If-None-Match")
        Dim freshness As New TimeSpan(100, 0, 0, 0)
        context.Response.Cache.SetCacheability(HttpCacheability.Public)
        context.Response.Cache.SetExpires(DateTime.Now.ToUniversalTime.Add(freshness))
        context.Response.Cache.SetMaxAge(freshness)
        context.Response.Cache.SetValidUntilExpires(True)
        context.Response.Cache.VaryByHeaders("Accept-Encoding") = True
        context.Response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches)
        Dim outgoingEtag As String = context.Request.Url.Authority & context.Request.Url.Query.GetHashCode()
        context.Response.Cache.SetETag(outgoingEtag)
CSS: 空白删除函数示例
    Private Function StripWhitespace(ByVal body As String) As String
        body = body.Replace("  ", " ")
        body = body.Replace(Environment.NewLine, [String].Empty)
        body = body.Replace(vbTab, String.Empty)
        body = body.Replace(" {", "{")
        body = body.Replace(" :", ":")
        body = body.Replace(": ", ":")
        body = body.Replace(", ", ",")
        body = body.Replace("; ", ";")
        body = body.Replace(";}", "}")
        ' sometimes found when retrieving CSS remotely
        body = body.Replace("?", String.Empty)
        'body = Regex.Replace(body, @"/'*[^'*]*'*+([^/'*]*'*+)*/", "$1");
        body = Regex.Replace(body, "(?<=[>])'s{2,}(?=[<])|(?<=[>])'s{2,}(?=&nbsp;)|(?<=&ndsp;)'s{2,}(?=[<])", [String].Empty)
        'Remove comments from CSS
        body = Regex.Replace(body, "/'*['d'D]*?'*/", String.Empty)
        Return body
    End Function
: JS空白删除函数示例
    Private Function StripWhitespace(ByVal body As String) As String
        Dim lines As String() = body.Split(New String() {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries)
        Dim emptyLines As New StringBuilder()
        For Each line As String In lines
            Dim s As String = line.Trim()
            If s.Length > 0 AndAlso Not s.StartsWith("//") Then
                emptyLines.AppendLine(s.Trim())
            End If
        Next
        body = emptyLines.ToString()
        body = Regex.Replace(body, "^['s]+|[ 'f'r't'v]+$", [String].Empty)
        body = Regex.Replace(body, "([+-])'n'1", "$1 $1")
        body = Regex.Replace(body, "([^+-][+-])'n", "$1")
        body = Regex.Replace(body, "([^+]) ?('+)", "$1$2")
        body = Regex.Replace(body, "('+) ?([^+])", "$1$2")
        body = Regex.Replace(body, "([^-]) ?('-)", "$1$2")
        body = Regex.Replace(body, "('-) ?([^-])", "$1$2")
        body = Regex.Replace(body, "'n([{}()['],<>/*%&|^!~?:=.;+-])", "$1")
        body = Regex.Replace(body, "('W(if|while|for)'([^{]*?'))'n", "$1")
        body = Regex.Replace(body, "('W(if|while|for)'([^{]*?'))((if|while|for)'([^{]*?'))'n", "$1$3")
        body = Regex.Replace(body, "([;}]else)'n", "$1 ")
        body = Regex.Replace(body, "(?<=[>])'s{2,}(?=[<])|(?<=[>])'s{2,}(?=&nbsp;)|(?<=&ndsp;)'s{2,}(?=[<])", [String].Empty)
        Return body
    End Function

下面是压缩输出的示例:

        Dim request As HttpRequest = context.Request
        Dim response As HttpResponse = context.Response
        Dim browserAcceptedEncoding As String = request.Headers("Accept-Encoding")
        If Not String.IsNullOrEmpty(browserAcceptedEncoding) Then
            browserAcceptedEncoding = browserAcceptedEncoding.ToLowerInvariant
            If (browserAcceptedEncoding.Contains("gzip")) Then
                response.AppendHeader("Content-encoding", "gzip")
                response.Filter = New GZipStream(response.Filter, CompressionMode.Compress)
            ElseIf (browserAcceptedEncoding.Contains("deflate")) Then
                response.AppendHeader("Content-encoding", "deflate")
                response.Filter = New DeflateStream(response.Filter, CompressionMode.Compress)
            End If
        End If
相关文章：