Writing a GWT library

A GWT library can be used to package classes for mutualization and/or modularization. A GWT library is just a java archive (JAR) containing both classes and java sources for later GWT compilation and a gwt.xml module descriptor.

Packaging

The only distinction with a standard JAR project is the mix of sources and classes in the output folder. A simple way to achieve this is to add a dedicated resource in the POM :

    <resources>
      <resource>
        <directory>src/main/java</directory>
        <includes>
          <include>**/*.java</include>
          <include>**/*.gwt.xml</include>
        </includes>
      </resource>
    </resources>

Another option is to let the plugin detect the required source to be included, based on the module descriptor. The benefict is that the plugin will not include java files that are not declared as GWT source by the module descriptor, avoiding end-user to reference your internal classes (usually for library that include both client and server side components).

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>gwt-maven-plugin</artifactId>
        <version>1.1</version>
        <executions>
          <execution>
            <goals>
              <goal>resources</goal>
            </goals>
          </execution>
        </executions>
      </plugin>