How to get SPWebApplication for current request in HttpModule?

How can I get the SPWebApplication for the current request from a H开发者_开发百科ttpModule?

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try constructing the SPSite yourself

using(SPSite site = new SPSite(app.Context.Request.Url.ToString())) { //might need to trim the url
    site.WebApplication
}

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Tried SPContext.Current.Site.WebApplication ?