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4. Built-in HTTP filters

§Configuring gzip encoding

Play provides a gzip filter that can be used to gzip responses.

§Enabling the gzip filter

To enable the gzip filter, add the filter to application.conf:

play.filters.enabled += "play.filters.gzip.GzipFilter"

§Configuring the gzip filter

The gzip filter supports a small number of tuning configuration options, which can be configured from application.conf. To see the available configuration options, see the Play filters reference.conf.

§Controlling which responses are gzipped

You can control which responses are and aren’t gzipped based on their content types via application.conf:

play.filters.gzip {

    contentType {

        # If non empty, then a response will only be compressed if its content type is in this list.
        whiteList = [ "text/*", "application/javascript", "application/json" ]

        # The black list is only used if the white list is empty.
        # Compress all responses except the ones whose content type is in this list.
        blackList = []
    }
}

As a more flexible alternative you can use the shouldGzip parameter of the gzip filter itself, which accepts a function of a request header and a response header to a boolean.

For example, the code below only gzips HTML responses:

Scala

new GzipFilter(shouldGzip = (request, response) =>
  response.body.contentType.exists(_.startsWith("text/html")))

Java

GzipFilterConfig gzipFilterConfig = new GzipFilterConfig();
GzipFilter gzipFilter = new GzipFilter(
  gzipFilterConfig.withShouldGzip((BiFunction<Http.RequestHeader, Result, Object>) (req, res) ->
    res.body().contentType().orElse("").startsWith("text/html")
  ), materializer
);

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