freemarker获取request,session等

http://yezi.iteye.com/blog/58048
http://snipplr.com/view/3911/getting-http-request-properties-and-attributes-in-freemarker-template/
${Request["a"]}
${RequestParameters["a"]}
${Session ["a"]}
${Application ["a"]}
${JspTaglibs ["a"]}
注意RequestParameters等内部对象时常不能获得所以要:
${RequestParameters?default({})["_errors"]?default("params")}
${Request["request"]?default("request")}
${Session["session"]?default("session")}
${Application["ctx"]?default("ctx")}
${RequestParameters?default({})?keys?size}
${Request?keys?first}
Freemarker可以直接取pageContext,requestAttribute,session,application中的数据,就是不能取requestParameter;