Get request header from freemarker

问题

I want to create AJAX-navigation on my site with Freemarker as template engine. If page are requested with XMLHttpRequest, there is no need to include page header and footer. Code will be look like this:

[#if !XMLHttpRequest]
    [#include "header.ftl"]
[/#if]
${content}
[#if !XMLHttpRequest]
    [#include "footer.ftl"]
[/#if]

My question is how to define that the request came with AJAX. Client adds header X-Requested-With: XMLHttpRequest, and how do I get it in Freemarker? I tried to find it in HttpRequestHashModel:

[#assign XMLHttpRequest = Request.headers['X-Requested-With']=="XMLHttpRequest" /]

but it throws error Expression Request.headers is undefined. I also tried to use RequestParameters it can't help too.

回答1:

FreeMarker itself doesn't define any HTTP related variables; it's not like JSP, it's a general purpose engine; it only sees variables that were passed to it, and it doesn't know what they are... they are just name-value pairs as far as FreeMarker is concerned. So if you need this information, then either you should pass it to FreeMarker in the actions (maybe globally with a filter or interceptor or whatever you have), or the web application framework should.

来源：https://stackoverflow.com/questions/17648120/get-request-header-from-freemarker