Question

I have to use Annotation Processing (apt) and AspectJ in the same Maven project.

Both work for themselves, but I need to create aspects based on code created by apt. So I would need binary weaving (the original source files are extended by apt). How can I enable binary weaving within a maven project?

I know the only standard option is to supply a dependency using the weaveDependencies parameter, but this is awful. Is there any other way?

OK, I could embed the AspectJ ant tasks using the Maven Antrun Plugin but I’d hate to resort to that.

Answer 1

I am apparently the only one who can answer my own questions.

I have resorted to compiling AspectJ via ant using the Maven Antrun Plugin. Here’s my pom snippet:

<plugin>
    <artifactId>maven-antrun-plugin</artifactId>
    <version>1.4</version>
    <dependencies>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjtools</artifactId>
            <version>${aspectj.version}</version>
        </dependency>
    </dependencies>
    <executions>
        <execution>
            <id>ajc-compile</id>
            <phase>process-classes</phase>
            <configuration>
                <tasks>
                    <property name="aspectj.sourcepath"
                        value="${project.basedir}/src/main/aspect" />
                    <property name="aspectj.binarypath"
                        value="${project.build.outputDirectory}" />
                    <property name="aspectj.targetpath"
                        value="${project.build.directory}/aspectj-classes" />
                    <property name="scope_classpath" refid="maven.compile.classpath" />
                    <property name="plugin_classpath" refid="maven.plugin.classpath" />
                    <ant antfile="ajc-ant.xml" />
                </tasks>
            </configuration>
            <goals>
                <goal>run</goal>
            </goals>
        </execution>
        <execution>
            <id>ajc-test-compile</id>
            <phase>process-test-classes</phase>
            <configuration>
                <tasks unless="maven.test.skip">
                    <property name="aspectj.sourcepath"
                        value="${project.basedir}/src/test/aspect;${project.basedir}/src/main/aspect" />
                    <property name="aspectj.binarypath"
                        value="${project.build.testOutputDirectory}" />
                    <property name="aspectj.targetpath"
                        value="${project.build.directory}/aspectj-test-classes" />
                    <property name="scope_classpath" refid="maven.test.classpath" />
                    <property name="plugin_classpath" refid="maven.plugin.classpath" />
                    <ant antfile="ajc-ant.xml" />
                </tasks>
            </configuration>
            <goals>
                <goal>run</goal>
            </goals>
        </execution>
    </executions>
</plugin>

I compile java classes first (and let APT do it’s stuff), use the compiled classes as binary input for aspectj, compile aspectj into a new folder and move the resulting woven classes to the original compile directory, overwriting the non-aspectj classes. Here’s my ant XML file (the nice part is that I can use it for both compile and test-compile):

<project basedir="." default="ajc">
    <path id="classpath">
        <pathelement path="${scope_classpath}" />
        <pathelement path="${plugin_classpath}" />
    </path>
    <taskdef
        classname="org.aspectj.tools.ant.taskdefs.AjcTask"
        name="iajc" classpathref="classpath" />
    <target name="ajc">
        <iajc
            sourceroots="${aspectj.sourcepath}"
            inpath="${aspectj.binarypath}"
            destdir="${aspectj.targetpath}"
            classpathref="classpath"
            source="1.6"
            target="1.6"
        />
        <move todir="${aspectj.binarypath}">
            <fileset dir="${aspectj.targetpath}">
                <include name="**/*.class" />
            </fileset>
        </move>
    </target>
</project>

---

In the next step I have now created a Maven Plugin that does all this ant calling internally. While I can’t share the code here, I’ll show how it simplified POM configuration:

<plugin>
    <groupId>com.myclient.maven.plugins</groupId>
    <artifactId>maven-ajc-plugin</artifactId>
    <version>1.0-SNAPSHOT</version>
    <executions>
        <execution>
            <id>compile-ajc</id>
            <goals>
                <goal>compile</goal>
            </goals>
        </execution>
        <execution>
            <id>testcompile-ajc</id>
            <goals>
                <goal>test-compile</goal>
            </goals>
            <configuration>
                <aspectSourcePath>${project.basedir}/src/main/aspect</aspectSourcePath>
            </configuration>
        </execution>
    </executions>
    <configuration>

    </configuration>
</plugin>

Using ANT / GMaven integration, it was easy to assembly the parameters combining the powers of Maven, Groovy and Ant.