How to use groovy interpreted (with spring-aop annotation) within an spring boot 2 java application build with maven?

Question

I have a spring boot 2 java app and would like to use interpreted (not compiled) groovy code to inject aop. From reading the spring documentation this sounds like it is possible, but I could'nt find any examples. AOP - advising scripted beans:

You are of course not just limited to advising scripted beans…​ you can also write aspects themselves in a supported dynamic language and use such beans to advise other Spring beans. This really would be an advanced use of the dynamic language support though.

At the end I would like to have a directory where I could add groovy scripts (for business logic) to the application that will inject themself via spring-aop.

What I am not sure about is what is spring boot 2 automagically doing in such a case, or do I have to integrate code based on org.springframework.scripting manually?

So here is my small test project:

project
|-pom.xml
|src/main/java/de/test
|-Commandline.java
|-MytestApplication.java
|-TestConfig.java
|-GetText.java
|src/main/resources/groovy
|-testAspect.groovy
|src/main/resources
|-application.properties   (empty at the moment)
|-applicationContext.xml

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>de.test</groupId>
  <artifactId>mytest</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>mytest</name>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.4.RELEASE</version>
    <relativePath/>
  </parent>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.codehaus.groovy</groupId>
      <artifactId>groovy</artifactId>
    </dependency>
  </dependencies>

</project>

TestConfig.java

package de.test;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

@Configuration
@EnableAspectJAutoProxy
@ComponentScan({"de.test", "groovy"})
@ImportResource({"classpath*:applicationContext.xml"})
public class TestConfig
 {
 }

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans" xmlns:lang="http://www.springframework.org/schema/lang" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

  <lang:groovy id="testAspect" refresh-check-delay="30000" script-source="classpath:groovy/TestAspect.groovy"/>

</beans>

MytestApplication.java

package de.test;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@ComponentScan({"de.test", "groovy"})
@SpringBootApplication
public class SpringboottestApplication
 {
  public static void main(final String[] args)
   {
    SpringApplication.run(SpringboottestApplication.class, args);
   }
 }

GetText.java

package de.test;

import org.springframework.stereotype.Component;

@Component
public class GetText
 {
  public String getText()
   {
    return "test1";
   }

 }

Commandline.java

package de.test;

import org.springframework.boot.CommandLineRunner;  
import org.springframework.stereotype.Component;

@Component
public class Commandline implements CommandLineRunner
 {
  @Autowired
  GetText textbean;

  public Commandline()
   {
    super();
   }

  @Override
  public void run(final String... args) throws Exception
   {
    System.out.println((this.textbean.getText());
   }
 }

testAspect.groovy

package groovy

import org.springframework.stereotype.Component

import org.aspectj.lang.ProceedingJoinPoint
import org.aspectj.lang.annotation.Around
import org.aspectj.lang.annotation.Aspect

@Aspect
@Component
class TestAspect
 {
  @Around("execution(String de.test.GetText.getText())")
  public String doChangeGetText(ProceedingJoinPoint pjp) throws Throwable
   {
    String retVal = (String)pjp.proceed();
    return retVal + "; test2";
   }
 }

After

mvn clean install

I start it with

java -jar target/mytest-0.0.1-SNAPSHOT.jar

Which results in only "test1" as output instead of the wanted "test1; test2".

Update1:

• Added TestConfig.java
• Moved src/main/groovy/groovy/testAspect.groovy to src/main/resources/groovy/testAspect.groovy
• Improved some things, but still does not work.

Update2:

• Added GetText.java
• Modified Commandline.java to use GetText bean
• Changed PointCut
• Still doesn't work

Update3:

• Added applicationContext.xml
• Now runing in an org.springframework.aop.AopInvocationException: Mismatch on arguments to advice method [public java.lang.String groovy.TestAspect.doChangeGetText(org.aspectj.lang.ProceedingJoinPoint) throws java.lang.Throwable]; pointcut expression [org.aspectj.weaver.internal.tools.PointcutExpressionImpl@4c4f4365]; nested exception is java.lang.IllegalArgumentException: object is not an instance of declaring class
• When copying the testAspect.groovy over as java class - then the pointcut works as expected and ";test 2" will be appended, but as groovy script the above exception will haben.
• Adding an interface IGetText and/or IAspectTest will not help

Answer 1

This is a classic question and was asked dozens of times here:

Spring AOP does not intercept self-invocation within beans, only calls from other classes to public Spring bean methods. This is also documented in the Spring manual.