Precedence of XML vs. Annotation configuration

[wwheeler]

OK, here it is:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:p="http://www.springframework.org/schema/p"
	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-2.5.xsd
		http://www.springframework.org/schema/context
		http://www.springframework.org/schema/context/spring-context-2.5.xsd">

	<context:annotation-config/>
	
	<bean id="dao" class="example.Dao"/>
	
	<!-- dao is autowired into service, but maxClients isn't -->
	<bean id="service" class="example.Service" p:maxClients="2000"/>
	
</beans>

and a couple of Java classes:

package example;

public class Dao { }

package example;

import org.springframework.beans.factory.annotation.Autowired;

public class Service {
	private Dao dao;
	private int maxClients;
	
	@Autowired
	public void setDao(Dao dao) {
		System.out.println("Setting dao=" + dao);
		this.dao = dao;
	}
	
	public void setMaxClients(int maxClients) {
		System.out.println("Setting maxClients=" + maxClients);
		this.maxClients = maxClients;
	}
}

When I load up the context I get the following on the console:

INFO  DispatcherServlet - FrameworkServlet 'contact': initialization started
INFO  XmlWebApplicationContext - Refreshing org.springframework.web.context.support.XmlWebApplicationContext@3ef810: display name [WebApplicationContext for namespace 'contact-servlet']; startup date [Wed Jul 09 02:42:32 MST 2008]; root of context hierarchy
INFO  XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/contact/beans-servlet.xml]
INFO  XmlWebApplicationContext - Bean factory for application context [org.springframework.web.context.support.XmlWebApplicationContext@3ef810]: org.springframework.beans.factory.support.DefaultListableBeanFactory@11c2b67
INFO  DefaultListableBeanFactory - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@11c2b67: defining beans [org.springframework.context.annotation.internalPersistenceAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,dao,service]; root of factory hierarchy
Setting dao=example.Dao@c5e9c
Setting maxClients=2000
INFO  DispatcherServlet - FrameworkServlet 'contact': initialization completed in 891 ms

Hope that addresses what you're trying to do.

[timomeinen]

Dear Willie,

thank you very much for your work. I can't believe it works for you. This is exactly, what I want to do, but for me it don't work.

Beside this bean I have several other beans, which are autodetected via <context:component-scan>. Perhaps the problem is, that I have this feature set. Does the code still work for you, if you add <context:component-scan>?

Thank you
Timo

[Marten Deinum]

component-scan works ONLY with autowiring so if you have a @Repository bean it will only work with autowiring, configuration in XML for the same bean is ignored (well not exactly it will result in another bean instance).

Also when you have component-scan you don't need the annotation-config, that is automatically implied.

[timomeinen]

Hi Marten,

thanks for clarifying the component-scan issue. But how do you configure the bean properties, which cannot be autowired? Or does component-scan with autowiring just work for beans, which has only autowire-able references?

[wwheeler]

Timo, you lucky guy. I think I have something for you. :-)

I didn't realize that you were stuck with the component-scan for other beans. Now I see why that kept popping up in your examples.

So here's what you can do. Let's say your current application context file is called app-context.xml, and you are forced to keep component-scan in there. Simply add an import there, like this:

	<import resource="example-context.xml"/>

(OK, I don't know if one line of code justified using code tags, but Marten used the Force on me.)

OK, now that you have that, create the example-context.xml file, which is just the app context I gave above. Here it is again just to avoid confusion:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:p="http://www.springframework.org/schema/p"
	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-2.5.xsd
		http://www.springframework.org/schema/context
		http://www.springframework.org/schema/context/spring-context-2.5.xsd">
	
	<context:annotation-config/>
	
	<bean id="dao" class="example.Dao"/>
	
	<!-- dao is autowired into service, but maxClients isn't -->
	<bean id="service" class="example.Service" p:maxClients="2000"/>
</beans>

Basically this will make the example beans visible to your current application context, and yet it will allow you to isolate those so that you can define them without component scanning.

Let me know.