gwt-api-generator is a tool that produces GWT Java APIs for JavaScript libraries provided as input, assuming their APIs are decorated with JSDoc annotations.

Currently the generator only supports Web Components written in Polymer 1.0 syntax. Support for other type of JavaScript sources might be added in the future.

Original motivation behind the project was to provide GWT community an easy access to the elements in Vaadin Elements collection.

Notice: Vaadin transferred the ownership of this library to the community by 20 Apr 2017, thus Vaadin no longer provides support or does active development on it.

• Installation

$ npm install -g vaadin/gwt-api-generator

If you've installed node and npm using sudo, installing packages globally will also require you to use sudo. See http://givan.se/do-not-sudo-npm/ how to remedy the situation.

• Generating java code for bower packages installed in your bower_components folder

  $ bower install my-web-component
  $ gwt-api-generator

• Generating java code for a complete library

  $ gwt-api-generator --package=PolymerElements/paper-elements

• Generating resources with a custom groupId and artifactId

  $ gwt-api-generator --package=PolymerElements/paper-elements \
                    --groupId=com.foo --artifactId=bar

• Generating resources for a non-maven structure

  $ gwt-api-generator --package=PolymerElements/paper-elements
                      --javaDir=src --resourcesDir=src

• Generating maven pom.xml file and packaging the result as a ready-to-use .jar file

  $ gwt-api-generator --package=PolymerElements/paper-elements --pom
  $ mvn package

Vaadin officially maintains and supports a pre-built package deployed at Maven Central repository containing all the resources needed for using Polymer paper-elements, app-elements, platinum-elements, iron-elements and vaadin-core-elements in a GWT application.

Build script, demo and usage instructions for the project are available here.

You also might see all these components in action using the Show Case application

Whether you need a 3 party element not included in the prebuilt packages or you want to maintain your own set of components, you can setup your maven project to automatically generate Java interfaces during the build process just following the next steps.

1. Create a package.json with the gwt-api-generator package dependency:

    {
      "name": "my-app",
      "description": "my-app",
      "version": "1.0",
      "license": "my-prefered-license",
      "dependencies": {
        "gwt-api-generator": "vaadin/gwt-api-generator"
      }
    }
   

2. Create a bower.json to add all 3rd party elements your application depends on, in this example we add a library for binding data to pouchdb/couchdb databases:

    {
      "name": "my-app",
      "description": "my-app",
      "main": "",
      "license": "my-prefered-license",
      "dependencies": {
        "vaadin-pouchdb": "manolo/vaadin-pouchdb"
      }
    }
   

3. Make your maven build script to automatically install node, npm and bower, download all elements, generate java classes and bundle static stuff in your package:

    <!-- install node, npm, bower, and your components -->
    <plugin>
      <groupId>com.github.eirslett</groupId>
      <artifactId>frontend-maven-plugin</artifactId>
      <executions>
        <execution>
          <id>install node and npm</id>
          <phase>generate-resources</phase>
          <goals>
            <goal>install-node-and-npm</goal>
          </goals>
          <configuration>
            <nodeVersion>v6.2.0</nodeVersion>
          </configuration>
        </execution>
        <execution>
          <id>npm install</id>
          <goals>
            <goal>npm</goal>
          </goals>
          <configuration>
            <arguments>install</arguments>
          </configuration>
        </execution>
        <execution>
          <id>bower install</id>
          <goals>
            <goal>bower</goal>
          </goals>
          <configuration>
            <arguments>install</arguments>
          </configuration>
        </execution>
      </executions>
    </plugin>
   
    <!-- Generate java code for all web downloaded components -->
    <plugin>
      <artifactId>maven-antrun-plugin</artifactId>
      <version>1.7</version>
      <executions>
        <execution>
          <phase>generate-resources</phase>
          <configuration>
            <target>
              <exec
                dir="${project.basedir}"
                executable="node_modules/.bin/gwt-api-generator">
              </exec>
            </target>
          </configuration>
          <goals>
            <goal>run</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
   

Vaadin gwt-api-generator produces @JsType interfaces for JS Element level access from Java Objects.

Since JsInterop was a feature experimental in GWT-2.7.0 and stable in GWT-2.8.0, and its implementation has absolutly changed from the experimental to the stable API, we have decided not to support old releases anymore, starting with gwt-api-generator 1.2.1.

The gwt-polymer-elements library is bundled with all web components placed in a the bower_components folder. Though, the developer might change this location by setting the window.gwtBowerLocation property, or by calling the Polymer.setGwtBowerLocation(location) method in the application entry point.