Java Config - does it do everything you can do in XML?

[gamache]

Hi,

I spent a lot of time looking for the answer to this question and I hope someone (anyone?) who knows will respond.

I have existing XML-based configuration and am moving to Java Config. Using the XML-centric approach described in section 4.12 of version 3.1 of the spring framework doc. I simply want to create a Bean in Java Config that needs a Parent already defined in Spring XML. Is this possible? If so, please tell me how to do it! I have seen the question asked here in these forums twice before, but no one has replied at all. From other references, I surmised that one is supposedly able to do everything in Java Config that you can do in XML. This certainly seems pretty basic, but darned if I can figure it out!

More details for those folks that need it. The bean to be created via Java Config is a Java class that extends another Bean. The base bean/class has already been created and has a bunch of DI members that I need loaded. All of the beans are singletons.

thanks for any assistance!

[Marten Deinum]

I suggest a read of the reference guide as that explains how to do that. The section called 'Combining Java and XML configuration' should be a give away.

You have to use the ImportResource annotation.

[gamache]

I suggest a read of the reference guide as that explains how to do that. The section called 'Combining Java and XML configuration' should be a give away.

You have to use the ImportResource annotation.

Hi Marten,

Thanks for the response. However, I read that section and referenced it in my post. I don't need "ImportResource" as I am doing "XML-centric" not @Configuration-class-centric. The issue is not that the beans I declare in the XML are not in Spring. They are and they are properly created. The issue is how, from Java Config, do I create a child bean (from an @Bean annotated method), that has a parent bean defined in the XML. There is no use of "parent" in section 4.12 of the document you and I reference. Any ideas?

More specifically, what is the Java Config way of doing this XML:


<bean id="testDao" parent="abstractDao" class="com.company.package.SomeDaoClass">
<property name="aProperty" value="com.company.package.SomePropertyValue" />
</bean>

and please don't respond by saying "abstractDao" needs to be a member of the class. IS_A relationships are not semantically equivalent to HAS_A relationships even though they are both aggregation relationships. I would simply like to know, yes or no if this exact representation of XML is doable in Java Config - if it is, I can't figure out how to do it and welcome someone smarter than me to help me out!

Joe

[Marten Deinum]

You cannot specify a parent bean for beans configured in java configuration simply because it is java and the @Bean methods are used as factory methods. You could create a factory method/callback method to which you pass your beans to do the common configuration (you might need to do a bit of reflection but it would work).

@Configuration
public class MyConfig {
  
  @Autowired
  private Object yourParent;

  protected void configureBean(Object myBean) {
    // copy matching properties from parent to myBean
    // or simply retrieve and set the properties in the @Bean method
  }

  @Bean
  public MyBean bean1() {
    MyBean bean = new MyBean();
    configureBean(bean);
    bean.setProperty("value"):
    return bean;
  }

  @Bean
  public MyOtherBean bean2() {
    MyOtherBean bean = new MyOtherBean ();
    configureBean(bean);
    bean.setYetAnotherProperty("other_value"):
    return bean;
  }
}

[gamache]

Thank you - this is a huge help!