AopUtils.getTargetClass returns a proxy class for @Configuration beans [SPR-15573]

[spring-projects-issues]

M. Justin opened SPR-15573 and commented

I just discovered that AopUtils.getTargetClass will return the proxy class (not the target class) when requesting the bean for an @Configuration class.

Looking at the code for getTargetClass, it expects the object to be an instance of SpringProxy, but it is instead just an instance of ConfigurationClassEnhancer.EnhancedConfiguration — which does not implement SpringProxy.

The following simple Spring Boot application demonstrates this issue:

package example;

import org.springframework.aop.support.AopUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;

import javax.annotation.PostConstruct;
import java.util.Arrays;

@SpringBootApplication
public class ExampleApplication {
  @Autowired
  private ExampleConfiguration exampleConfiguration;

  public static void main(String[] args) {
    new SpringApplicationBuilder().sources(ExampleApplication.class).build().run();
  }

  @PostConstruct
  public void demonstrateIssue() {
    // class example.ExampleConfiguration$$EnhancerBySpringCGLIB$$2a89a1c2
    System.out.println(AopUtils.getTargetClass(exampleConfiguration));

    // class example.ExampleConfiguration
    System.out.println(AopUtils.getTargetClass(exampleConfiguration).getSuperclass());

    // [interface org.springframework.context.annotation.ConfigurationClassEnhancer$EnhancedConfiguration]
    System.out.println(Arrays.toString(AopUtils.getTargetClass(exampleConfiguration).getInterfaces()));
  }
}

package example;

import org.springframework.context.annotation.Configuration;

@Configuration
public class ExampleConfiguration {
}

---

Affects: 4.3.8

[spring-projects-issues]

Juergen Hoeller commented

This is by design: AopUtils.getTargetClass strictly only operates on AOP proxies with a distinct generated proxy instance and a separate unmodified target instance backing it. Configuration classes on the other hand are a single instance of a generated subclass and therefore not an AOP proxy in that sense; there is semantically no separate instance of an unmodified target class here.

If you'd like a common way to obtain the original class for CGLIB-generated classes, consider ClassUtils.getUserClass: This works for configuration classes as well as target-class proxies.