Unofficial Google Actions Java SDK - for Android engineers and all Java lovers
Latest commit e98f532 Jan 21, 2017 @frogermcs smaller simulator preview

Unofficial Google Actions Java SDK

Official Google Actions SDK is written in Node.js. But in many situations voice interfaces like Google Home or Google Assistant will extend or replace mobile apps. If you are old fashioned Android engineer and the most of your code is already written in Java, why not reuse it and build voice extension to app on your own? And this is the main reason to build Google Actions Java SDK - enabling as much developers as possible to build their brilliant ideas for Google Assistant and Home.

Currently this is just working proof of concept of Google Actions Java SDK. It means that there is no documentation, fixed interface, (not much) unit tests and many, many others.

Google Actions Java SDK is build based on official Node.js library, but it's not a mirror copy of it. The goal is to make it fully compatible with Conversational Protocol of Assistant Platform.

About project

Project is split into two modules:

Assistant Actions Java SDK

This code is responsible for handling requests and responses compatible with Conversational Protocol.

Assistant Actions Java Sample

Example projects showing how Assistant Actions SDK can be used in AppEngine Java project. For now Servlet is able to greet user and repeat utterance.

How to work with limited SDK

Even if it's very early stage project and there is not much utils in it, whole communication with Google Actions is based on proper responses. So even if you find any limitations you can always build RootResponse object by hand which in a moment of writing this is fully compatible with Conversational Protocol. Same with RootRequest - object should reflect all data which Google Actions send to us.


Here is example code showing how to use Google Actions Java SDK

AssistantActions assistantActions =
        new AssistantActions.Builder(new AppEngineResponseHandler(response))
                .addRequestHandlerFactory(StandardIntents.MAIN, new MainRequestHandlerFactory())
                .addRequestHandlerFactory(StandardIntents.TEXT, new TextRequestHandlerFactory())


To build AssistantActions object, we need to pass implementation of ResponseHandler interface. This class will be responsible for passing json response to Google Actions. Then we need to build intents mapping to delegate request to proper RequestHandlers. RequestHandlers are responsible for preparing response for Google Actions.
At the end we need to pass request coming from Google Actions to our AssistantActions object.

Example implementation

Here are the most important classes from example AppEngine Java implementation

ActionsServlet - entry class in our endpoint.

public class ActionsServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        AssistantActions assistantActions =
                new AssistantActions.Builder(new AppEngineResponseHandler(response))
                        .addRequestHandlerFactory(StandardIntents.MAIN, new MainRequestHandlerFactory())
                        .addRequestHandlerFactory(StandardIntents.TEXT, new TextRequestHandlerFactory())



AppEngineResponseHandler - implementation or ResponseHandler. Method onResponse() is passing back prepared response to HttpServletResponse.

public class AppEngineResponseHandler implements ResponseHandler {
    private final HttpServletResponse httpServletResponse;

    public void onPrepareContentType(String contentType) {

    public void onPrepareResponseHeaders(Map<String, String> headers) {
        for (String headerName : headers.keySet()) {
            httpServletResponse.addHeader(headerName, headers.get(headerName));

    public void onResponse(RootResponse rootResponse) {
        gson.toJson(rootResponse, httpServletResponse.getWriter());

MainRequestHandler - In response to initial Intent assistant.intent.action.MAIN we are asking user to tell something.

public class MainRequestHandler implements RequestHandler {
    public RootResponse onRequest(RootRequest rootRequest) {
        return ResponseBuilder.askResponse("Hey, it works! Now tell something so I could repeat it.");

How to deploy this project to our Google Cloud

This description isn't very detailed. It's pretty similar to description in official documentation, but instead of Node.js we are using Java environment on AppEngine.

Google Cloud

  • Follow steps from here: At the end you should have created Project, know your application id, and be able to use gcloud on your computer.


Files to edit:

  • google-actions-java-sample/src/main/webapp/WEB-INF/appengine-web.xml -> Edit application_id (your project id from, if not edited it's fancy name like "mythic-origin-36343").
  • google-actions-java-sample/action.json -> Edit application_id (setup endpoint where Google Actions will be able to reach your servlet)

If you have Google Cloud SDK already installed on you machine, and you are ready to deploy, use this gradle task:

$ ./gradlew google-actions-java-sample:appengineDeploy


Just visit Web Simulator and start testing!

Web Simulator


This is very general list of things planned to do to make this project as useful as possible. Your commitment is highly appreciated!

  • Better project structure, code cleanup and style rules
  • Javadoc
  • Ask for permission feature
  • Add ssml support to responses
  • API.AI support (based on official SDK)
  • Keep conversation context
  • Unit tests (at least 70% coverage)
  • Build and distribute as a java library