I needed to compile AspectJ classes (.java with annotations) with ajc and I wanted to have that integrated into the Maven build process. I tried several means, finally finding the one that worked.

Note: I had to use ajc even though I was using the pure java 5 syntax based on annotations instead of the legacy AspectJ syntax due to bug in AspectJ (fixed in v. 1.6.6).

Failed Attempts

aspectj-maven-plugin v1.2

First I tried the AspectJ Maven plugin but it didn't work for me because I had a special need - a project containing only an aspect while the plugin requires, if I remember correctly, also the advised sources to be in the project. A fix is available and should be included in the version 1.3 but the project doesn't seem to be very active so who knows when it will be released. See MASPECTJ-7.

maven-compiler-plugin for aspectj

Next I tried the maven-compiler-plugin, which supports various back-ends including AspectJ with the dependency on plexus-compiler-aspectj and compilerId set to aspectj. Unfortunately the plexus-compiler-aspectj is quite out of date, supporting only AspectJ 1.3 while I needed 1.6.

Finally the Success: maven-antrun-plugin

Being failed by Maven plugins, I had to resort to the standard way of running ajc via Ant. Fortunately Maven has a very good integration of Ant and its tasks.

The only problem here was that Ant requires ${java.home} to point to JDK (and not JRE) to find javac. It doesn't help to set the envrionmental variable JAVA_HOME to point to the JDK because Maven resets it to $JAVA_HOME/jre in the case - see MANTRUN-91. The solution is to add tools.jar (which includes javac classes) to maven-antrun-plugin's dependencies.

The corresponding piece of pom.xml:

<build>
<plugins>
  <plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <!-- Tell javac not to compile sources for antrun will do it -->
    <configuration>
        <excludes>
            <exclude>**/*.*</exclude>
        </excludes>
    </configuration>
  </plugin>

  <plugin>
    <artifactId>maven-antrun-plugin</artifactId>
    <version>1.3</version>
    <dependencies>
      <dependency>
        <groupId>sun.jdk</groupId>
        <artifactId>tools</artifactId>
        <version>1.5.0</version>
        <scope>system</scope>
        <systemPath>${java.home}/../lib/tools.jar</systemPath>
      </dependency>
      <dependency>
        <groupId>org.aspectj</groupId>
        <artifactId>aspectjtools</artifactId> <!-- apectj ant plugin -->
        <version>1.6.0</version>
      </dependency>
    </dependencies>

    <executions>
      <execution>
        <phase>compile</phase>
        <goals>
          <goal>run</goal>
        </goals>
        <configuration>
          <tasks>
            <echo>AntRun: Compiling AspectJ classes with ajc, java.home=${java.home}</echo>
            <taskdef
              resource="org/aspectj/tools/ant/taskdefs/aspectjTaskdefs.properties"
              classpathref="maven.plugin.classpath" />

            <iajc
              srcDir="src/main/java"
              destDir="target/classes"
              verbose="true"
              showWeaveInfo="true"
              source="1.5"
              classpathRef="maven.compile.classpath"
              Xlint="ignore" >

              <exclude name="eu/ibacz/pbns/util/aspect/ExampleTimingAnnotatedAspect.java"/>
            </iajc>

          </tasks>
        </configuration>
      </execution>
    </executions>
  </plugin>
</plugins>
</build>

Note: maven-antrun-plugin v1.3 uses Ant 1.7.1 - see http://maven.apache.org/plugins/maven-antrun-plugin/dependencies.html

Conclusion

It's a bit tricky but very well possible to run AspectJ compiler instead of javac during a maven build. The most flexible way is to use the AspectJ Ant task and maven-antrun-plugin though in more standard cases the aspectj-maven-plugin can serve you well too.

Tags: java library tool