HTTP Cache for Action Results, Play Framework 2.0

Application.scala

package controllers

import play.api._
import play.api.cache._
import play.api.libs._
import play.api.mvc._
import play.api.Play.current

trait HttpCache {
  self:Controller =>
  
  // Set http.cachetime in application.conf to determine cache ttl.
  // Defaults to 120 seconds.
  // Sample: http.cachetime=3600
  
  val cacheTime = Play.configuration getInt "http.cachetime" getOrElse 120
  
  val rfcFormat = {
    val sdf = new java.text.SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z")
    sdf setTimeZone { java.util.TimeZone getTimeZone "GMT" }
    sdf
  }
  
  def HttpCache[A] (action: Action[A]): Action[A] = {
    Action(action.parser) { request =>
      val cacheKey = "url-" + request.host + request.uri
      
      // Retrieve the Result from the cache or run the action
      // if it doesn't exist, and set the appropriate Cache-Control
      // and Last-Modified headers.
      
      val (cachedResponse:Result, modTime:Double) = Cache get cacheKey getOrElse {
        val date = new java.util.Date
        val expires = new java.util.Date(date.getTime + cacheTime * 1000)
        val response = action(request).asInstanceOf[SimpleResult[A]]
          .withHeaders (CACHE_CONTROL -> { "public, max-age=" + cacheTime })
          .withHeaders (LAST_MODIFIED -> { rfcFormat format date })
          .withHeaders (EXPIRES -> { rfcFormat format expires })
        val modTime:Double = math floor { date.getTime / 1000 }
        Cache set (cacheKey, (response, modTime), cacheTime)
        (response, modTime)
      }
      
      // Check for If-Modified-Since in the request and send a
      // 304 response if the cached item hasn't changed, otherwise
      // send the original Result.
      
      request.headers get IF_MODIFIED_SINCE filter { dateStr =>
        math.floor({ try {
          rfcFormat parse dateStr
        } catch {
          case e => new java.util.Date(1)
        }}.getTime / 1000) >= modTime
      } map { _ => NotModified } getOrElse cachedResponse
    }
  }
}


// Add the HttpCache trait to the Controller.

object Application extends Controller with HttpCache {
  
  def index = Action {
    Ok(views.html.index("Your new application is ready."))
  }
  
  // An example of how to wrap the action with the HttpCache function.
  
  def test = HttpCache { 
    Action { 
      Ok("Date: "+new java.util.Date) 
    }
  }
  
}