qdrk / play-html-compressor

Google's HTML Compressor for Play Framework 2

Google's HTML (and XML) Compressor for Play Framework 2

Installation

In your project/Build.scala:

libraryDependencies ++= Seq(
  "com.mohiva" %% "play-html-compressor" % "0.3"
)

If you want to use the latest snapshot, add the following instead:

resolvers += "Sonatype Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots/"

libraryDependencies ++= Seq(
  "com.mohiva" %% "play-html-compressor" % "0.4-SNAPSHOT"
)

History

• For Play Framework 2.3 use version 0.3
• For Play Framework 2.2 use version 0.2.1
• For Play Framework 2.1 use version 0.1-SNAPSHOT

How to use

The filter comes with built-in HtmlCompressor and XmlCompressor configurations, but it can also be used with user-defined configurations. The following two examples shows how to define the filters with the default and the user-defined configurations.

Default filter

The default HTMLCompressorFilter has the same configuration as the user-defined filter below.

For Scala users

import play.api.mvc.WithFilters
import com.mohiva.play.htmlcompressor.HTMLCompressorFilter
import com.mohiva.play.xmlcompressor.XMLCompressorFilter

/**
 * Uses the default implementation of the HTML and XML compressor filters.
 */
object Global extends WithFilters(HTMLCompressorFilter(), XMLCompressorFilter())

For Java users

import play.GlobalSettings;
import play.api.mvc.EssentialFilter;
import com.mohiva.play.htmlcompressor.java.HTMLCompressorFilter;
import com.mohiva.play.xmlcompressor.java.XMLCompressorFilter;

/**
 * Uses the default implementations of the HTML and XML compressor filters.
 */
public class Global extends GlobalSettings {

    /**
     * Get the filters that should be used to handle each request.
     */
    @SuppressWarnings("unchecked")
    public <T extends EssentialFilter> Class<T>[] filters() {
        return new Class[] {
            HTMLCompressorFilter.class,
            XMLCompressorFilter.class
        };
    }
}

User-defined filter

For Scala users

import play.api.mvc.WithFilters
import play.api.Play
import play.api.Play.current
import com.googlecode.htmlcompressor.compressor.HtmlCompressor
import com.mohiva.play.htmlcompressor.HTMLCompressorFilter

/**
 * Uses a user-defined implementation of the HTML compressor filter.
 */
object Global extends WithFilters(HTMLCompressorFilter())

/**
 * Defines a user-defined HTML compressor filter.
 */
object HTMLCompressorFilter {

  /**
   * Creates the HTML compressor filter.
   *
   * @return The HTML compressor filter.
   */
  def apply() = new HTMLCompressorFilter({
    val compressor = new HtmlCompressor()
    if (Play.isDev) {
      compressor.setPreserveLineBreaks(true)
    }

    compressor.setRemoveComments(true)
    compressor.setRemoveIntertagSpaces(true)
    compressor.setRemoveHttpProtocol(true)
    compressor.setRemoveHttpsProtocol(true)
    compressor
  })
}

For Java users

import play.Play;
import play.GlobalSettings;
import play.api.mvc.EssentialFilter;
import com.mohiva.play.htmlcompressor.java.HTMLCompressorFilter;
import com.mohiva.play.htmlcompressor.java.HTMLCompressorBuilder;

/**
 * Uses a user-defined implementation of the HTML compressor filter.
 */
public class Global extends GlobalSettings {

    /**
     * Get the filters that should be used to handle each request.
     */
    @SuppressWarnings("unchecked")
    public <T extends EssentialFilter> Class<T>[] filters() {
        return new Class[]{CustomHTMLCompressorFilter.class};
    }

    /**
     * Custom implementation of the HTML compressor filter.
     */
    public static class CustomHTMLCompressorFilter extends HTMLCompressorFilter {
        public CustomHTMLCompressorFilter() {
            super(new CustomHTMLCompressorBuilder());
        }
    }

    /**
     * The builder for the custom HTML compressor.
     */
    public static class CustomHTMLCompressorBuilder implements HTMLCompressorBuilder {
        public HtmlCompressor build() {
            HtmlCompressor compressor = new HtmlCompressor();
            if (Play.isDev()) {
                compressor.setPreserveLineBreaks(true);
            }

            compressor.setRemoveComments(true);
            compressor.setRemoveIntertagSpaces(true);
            compressor.setRemoveHttpProtocol(true);
            compressor.setRemoveHttpsProtocol(true);
            return compressor;
        }
    }
}

User-defined XMLCompressorFilter

You can also use a user defined XMLCompressorFilter. The approach is analogical to the examples given above.

HTMLCompressorFilter & GzipFilter

Be careful when using HTMLCompressorFilter in combination with the Play GzipFilter. HTMLCompressorFilter can not work on source that has already been gzipped.

Unfortunately, there is no official way to control the order in which filters will be applied to responses.

Fortunately, Play Framework will apply the filters in reverse order of appearance in the WithFilters constructor. So this code will work as expected (applying HTMLCompressorFilter first and GzipFilter on the compressed HTML):

object Global extends WithFilters(new GzipFilter(), HTMLCompressorFilter()) {
  ...
}

This code will not work, resulting in an empty response body (or worse):

object Global extends WithFilters(HTMLCompressorFilter(), new GzipFilter()) {
  ...
}