Maven + AspectJ - all steps to configure it

java maven aspectj
alicjasalamon picture alicjasalamon · Sep 14, 2012 · Viewed 36.9k times · Source

I have a problem with applying aspects to my maven project. Probably I am missing something, so I've made a list of steps. Could you please check if it is correct?

Let say in projectA is an aspect class and in projectB classes, which should be changed by aspects.

  • Create maven project ProjectA with AspectJ class
  • add Aspectj plugin and dependency
  • Add ProjectA as a dependency to projectB pom.xml
  • Add to projectB pom.xml plugin
<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>aspectj-maven-plugin</artifactId>
    <version>1.4</version>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
                <goal>test-compile</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <source>${maven.compiler.source}</source>
        <target>${maven.compiler.target}</target>
        <aspectLibraries>
            <aspectLibrary>
                <groupId>ProjectA</groupId>
                <artifactId>ProjectA</artifactId>
            </aspectLibrary>
        </aspectLibraries>
    </configuration>
</plugin>
  • Add aspectj dependency

After all these steps my problem is, that during compilation I get:

[WARNING] advice defined in AspectE has not been applied [Xlint:adviceDidNotMatch]

And then when I run my program:

Exception in thread "FeatureExcutionThread" java.lang.NoClassDefFoundError: AspectE

Answer

maba picture maba · Sep 18, 2012

I traced some of your older questions to try to find out what you actually are trying to do. I have come up with the following structure and code and for me it works well.

$ tree .
.
├── pom.xml
├── ProjectA
|   ├── pom.xml
|   └── src
|       └── main
|           └── aspect
|               └── com
|                   └── stackoverflow
|                       └── aspects
|                           ├── AspectL.java
|                           └── Trace.aj
└── ProjectB
    ├── pom.xml
    └── src
        └── main
            └── java
                └── com
                    └── stackoverflow
                        └── App.java

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.stackoverflow</groupId>
    <artifactId>Q12423965</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>

    <name>${project.artifactId}-${project.version}</name>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.6</maven.compiler.source>
        <maven.compiler.target>1.6</maven.compiler.target>
    </properties>

    <modules>
        <module>ProjectA</module>
        <module>ProjectB</module>
    </modules>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.stackoverflow</groupId>
                <artifactId>Q12423965-ProjectA</artifactId>
                <version>${project.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.codehaus.mojo</groupId>
                    <artifactId>aspectj-maven-plugin</artifactId>
                    <version>1.4</version>
                    <executions>
                        <execution>
                            <goals>
                                <goal>compile</goal>
                                <goal>test-compile</goal>
                            </goals>
                        </execution>
                    </executions>
                    <configuration>
                        <source>${maven.compiler.source}</source>
                        <target>${maven.compiler.target}</target>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>2.5.1</version>
                    <configuration>
                        <source>${maven.compiler.source}</source>
                        <target>${maven.compiler.target}</target>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

ProjectA/pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.stackoverflow</groupId>
        <artifactId>Q12423965</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>Q12423965-ProjectA</artifactId>

    <name>${project.artifactId}-${project.version}</name>

    <dependencies>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.6.11</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>aspectj-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

I have created two differenct aspects. One that uses @AspectJ annotations and another one that is defined as a classic AspectJ aspect.

AspectL.java

package com.stackoverflow.aspects;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;

/**
 * @author maba, 2012-09-18
 */
@Aspect
public class AspectL {

    @Pointcut("execution(* main(..))")
    public void defineEntryPoint() {
    }

    @Before("defineEntryPoint()")
    public void aaa(JoinPoint joinPoint) {
        System.out.println("aspect before");
    }

    @After("defineEntryPoint()")
    public void bbb(JoinPoint joinPoint) {
        System.out.println("aspect after");
    }
}

Trace.aj

package com.stackoverflow.aspects;

public aspect Trace {
    pointcut publicMethodExecuted(): execution(public !static * *(..));

    after(): publicMethodExecuted() {
        System.out.printf("Enters on method: %s. \n", thisJoinPoint.getSignature());

        Object[] arguments = thisJoinPoint.getArgs();
        for (int i =0; i < arguments.length; i++){
            Object argument = arguments[i];
            if (argument != null){
                System.out.printf("With argument of type %s and value %s. \n", argument.getClass().toString(), argument);
            }
        }
        System.out.printf("Exits method: %s. \n", thisJoinPoint.getSignature());
    }
}

Those two files are part of the ProjectA module and are part of a jar.

Now we want to use these aspects and weave them into the code of ProjectB.

ProjectB/pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.stackoverflow</groupId>
        <artifactId>Q12423965</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>Q12423965-ProjectB</artifactId>

    <name>${project.artifactId}-${project.version}</name>

    <dependencies>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.6.11</version>
        </dependency>
        <dependency>
            <groupId>org.stackoverflow</groupId>
            <artifactId>Q12423965-ProjectA</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>aspectj-maven-plugin</artifactId>
                <configuration>
                    <aspectLibraries>
                        <aspectLibrary>
                            <groupId>org.stackoverflow</groupId>
                            <artifactId>Q12423965-ProjectA</artifactId>
                        </aspectLibrary>
                    </aspectLibraries>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>java</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <mainClass>com.stackoverflow.App</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

App.java

package com.stackoverflow;

/**
 * @author maba, 2012-09-17
 */
public class App {

    public void hello(String name) {
    }

    public static void main(String[] args) {
        App app = new App();
        app.hello("world");
    }
}

I build everything from top pom:

mvn clean install

And then go into the ProjectB directory and run the app:

mvn exec:java

The result is:

aspect before
Enters on method: void com.stackoverflow.App.hello(String). 
With argument of type class java.lang.String and value world. 
Exits method: void com.stackoverflow.App.hello(String). 
aspect after

So to conclude both aspects are working and the maven setup also works.

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