寻找一个HttpHandler的修改对飞页指向一个CDN [英] Looking for a HTTPHandler to modify pages on the fly to point to a CDN

问题描述

我想要做的就是创建（或者已经存在），将过滤HTML一个HttpHandler的产生ASP.NET使用内容分发网络（CDN）。例如，我想引用改写像这样的：

What I'm trying to do is create (or perhaps one already exists) a HTTPHandler that will filter the HTML generated ASP.NET to use the content delivery network (CDN). For example, I want to rewrite references such as this:

/Portals/_default/default.css

/Portals/_default/default.css

到

<一个href=\"http://cdn.example.com/Portals/_default/default.css\">http://cdn.example.com/Portals/_default/default.css

我完全乐意使用正则表达式匹配初始字符串。这样的正则表达式模式可能是：

I'm perfectly happy using RegEx to match the initial strings. Such a regex patterns might be:

href=['"](/Portals/.+\.css)

或

src=['"](/Portals/.+\.(css|gif|jpg|jpeg))

这是一个DotNetNuke的网站，我真的不拥有控制权产生的所有HTML所以这就是为什么我要与一个HttpHandler做到这一点。这样的变化可以做到页后生成。

This is a dotnetnuke site and I don't really have control over all the HTML generated so that's why I want to do it with an HTTPHandler. That way the changes can be done post-page generation.

推荐答案

您可以写一个响应滤波器可自定义HTTP模块中进行注册，而且还会修改所有网页生成的HTML运行您呈现正则表达式。

You could write a response filter which can be registered in a custom HTTP module and which will modify the generated HTML of all pages running the regex you showed.

例如：

public class CdnFilter : MemoryStream
{
    private readonly Stream _outputStream;
    public CdnFilter(Stream outputStream)
    {
        _outputStream = outputStream;
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        var contentInBuffer = Encoding.UTF8.GetString(buffer);

        contentInBuffer = Regex.Replace(
            contentInBuffer, 
            @"href=(['""])(/Portals/.+\.css)",
            m => string.Format("href={0}http://cdn.example.com{1}", m.Groups[1].Value, m.Groups[2].Value)
        );

        contentInBuffer = Regex.Replace(
            contentInBuffer,
            @"src=(['""])(/Portals/.+\.(css|gif|jpg|jpeg))",
            m => string.Format("href={0}http://cdn.example.com{1}", m.Groups[1].Value, m.Groups[2].Value)
        );

        _outputStream.Write(Encoding.UTF8.GetBytes(contentInBuffer), offset, Encoding.UTF8.GetByteCount(contentInBuffer));
    }
}

，然后写一个模块：

and then write a module:

public class CdnModule : IHttpModule
{
    void IHttpModule.Dispose()
    {
    }

    void IHttpModule.Init(HttpApplication context)
    {
        context.ReleaseRequestState += new EventHandler(context_ReleaseRequestState);
    }

    void context_ReleaseRequestState(object sender, EventArgs e)
    {
        HttpContext.Current.Response.Filter = new CdnFilter(HttpContext.Current.Response.Filter);
    }
}

和在web.config中注册：

and register in web.config:

<httpModules>
  <add name="CdnModule" type="MyApp.CdnModule, MyApp"/>
</httpModules>

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