Writing custom filters for Play! 2.2 in Java

Question

I have a simple scenario: automatically add a response header to every HTTP response; and I want to do this in Java.

Looking at src/play-filters-helpers/src/ma

Answer 1

Unfortunately there isn't a good way to create and use Filters from Java yet. But you can do what you need pretty easily with Scala.

Create a new file app/filters/AddResponseHeader.scala containing:

package filters

import play.api.mvc._
import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global

object AddResponseHeader extends Filter {
  def apply(f: (RequestHeader) => Future[SimpleResult])(rh: RequestHeader): Future[SimpleResult] = {
    val result = f(rh)
    result.map(_.withHeaders("FOO" -> "bar"))
  }
}

And create a new file app/Global.scala containing:

import filters.AddResponseHeader
import play.api.mvc.WithFilters

object Global extends WithFilters(AddResponseHeader)

That should apply a new response header to every response.

UPDATE: There is a way to use this in a Global.java file:

@Override
public  Class[] filters() {
    return new Class[] {AddResponseHeader.class};
}

And also change the object AddResponseHeader above to class AddResponseHeader.