FactoryBeans returning a @ManagedResource annotated subclass are not auto detected by MBeanExporter [SPR-6540]

[spring-projects-issues]

Jeffrey Sinclair opened SPR-6540 and commented

Take the following application context:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">

  <bean id="customer" class="spring.test.CustomerFactory">
    <property name="name" value="Jeff Sinclair" />
  </bean>

  <bean id="mbeanExporter" class="org.springframework.jmx.export.annotation.AnnotationMBeanExporter">
    <property name="autodetect" value="true" />
  </bean>

</beans>

with CustomerFactory being defined as:

public class CustomerFactory implements FactoryBean<Customer> {

    private String name;

    @Override
    public Customer getObject() throws Exception {
        return new DefaultCustomer(this.name);
    }

    @Override
    public Class<? extends Customer> getObjectType() {
        return Customer.class;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

    public void setName(String name) {
        this.name = name;
    }
}

with the Customer interface being defined as:

public interface Customer {
    public String getName();   
}

with the DefaultCustomer impl being defined as:

@ManagedResource
public class DefaultCustomer implements Customer {

    private String name;

    public DefaultCustomer(String name) {
        this.name = name;
    }

    @Override
    @ManagedAttribute
    public String getName() {
        return name;
    }
}

Since the autodetect logic only sees the Customer class (which is not annotated with @ManagedResource) it does not export the DefaultCustomer instance (which is annotated with @ManagedResource).

There is also the problem that even if the Customer was annotated with @ManagedResource the bean definition must be before the MBeanExporter's bean definition for this to work.

I added a comment to the following JIRA #10595 describing this issue providing the suggestion that a BeanPostProcessor (perhaps implementing InstantiationAware) would be more suitable for the auto detection logic.

---

Affects: 3.0 RC3

1 votes, 2 watchers

[spring-projects-issues]

Juergen Hoeller commented

I'm afraid you'll have to expose the full DefaultCustomer.class from your getObjectType() method there. We generally recommend implementing that method to return the most specific type possible, even if the FactoryBean is generically typed to a plain interface type such as FactoryBean<Customer>. Otherwise you're 'hiding' the specific type and hence prevent introspection of the implementation type; this can be used deliberately but in your case it's not intentional I suppose.

The ordering issue has been sorted out for 3.0 GA now, as commented on #10595. Thanks for raising that one again - it was nearly getting lost.

Juergen