Question

I have a multi-module build which contains modules which can target either Java 5 or Java 6. I want to allow modules to opt-in to Java 6, and leaving the default to 5.

To set Java 5 as a target I need to configure the following:

• maven-compiler-plugin: source and target set to 1.5
• maven-bundle-plugin: configure the Bundle-RuntimeExecutionEnvironment to J2SE-1.5

To set Java 6 as a target I need to configure the following:

• maven-compiler-plugin: source and target set to 1.6
• maven-bundle-plugin: configure the Bundle-RuntimeExecutionEnvironment to JavaSE-1.6

I considered having two properties: java.compiler.source and osgi.bree which can be defined by each module, but this leaves place for error.

How can I override the configuration of these two plugins per module with a single switch?

Answer 1

How about allowing child modules to set a my.java.version property (or whatever you want it named) and embedding a Groovy script that sets version properties for the compiler and bundle plugins? Something like this in the parent pom:

<project ...>
    ...
    <properties>
        <my.java.version>1.5</my.java.version>     <!-- default Java version -->
    </properties>
    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.groovy.maven</groupId>
                <artifactId>gmaven-plugin</artifactId>
                <version>1.0</version>
                <executions>
                    <execution>
                        <!-- set up properties in an early lifecycle phase -->
                        <phase>initialize</phase>
                        <goals>
                            <goal>execute</goal>
                        </goals>
                        <configuration>
                            <!-- this can be as simple or complex as you need it to be -->
                            <source>
                                if (project.properties['my.java.version'] == '1.6') {
                                    project.properties['my.compiler.version'] = '1.6'
                                    project.properties['my.execution.environment.version'] = 'JavaSE-1.6'
                                }
                                else {
                                    project.properties['my.compiler.version'] = '1.5'
                                    project.properties['my.execution.environment.version'] = 'J2SE-1.5'
                                }
                            </source>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
        <!-- now use the properties from above in the plugin configurations -->
        <!-- assume that both of these plugins will execute in a phase later than 'initialize' -->
        <pluginManagement>
            <plugins>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <source>${my.compiler.version}</source>
                        <target>${my.compiler.version}</target>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>org.apache.felix</groupId>
                    <artifactId>maven-bundle-plugin</artifactId>
                    <configuration>
                        <!-- sorry if this part isn't correct; never used this plugin before -->
                        <instructions>
                            <Bundle-RuntimeExecutionEnvironment>${my.execution.environment.version}</Bundle-RuntimeExecutionEnvironment>
                        </instructions>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>