Can spring framework override Annotation-based configuration with XML-based configuration? - spring

Question

Can spring framework override Annotation-based configuration with XML-based configuration? I need to change a dependency of a bean which is already defined via annotations and i am not the author of the bean.

Answer 1

i did not know that spring can mix configurations. here is the detailed and very useful example.
Bean1 is the actual bean we're configuring.
package spring;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
#Component
public class Bean1 {
private String naber;
#Autowired
#Qualifier("FireImpl1")
private Fire fire;
#PostConstruct
public void init() {
System.out.println("init");
getFire().fire();
}
#PreDestroy
public void destroy() {
System.out.println("destroy");
}
public void setNaber(String naber) {
this.naber = naber;
}
public String getNaber() {
return naber;
}
public void setFire(Fire fire) {
this.fire = fire;
}
public Fire getFire() {
return fire;
}
}
Fire is dependency interface
package spring;
public interface Fire {
public void fire();
}
and dummy implementation 1
package spring;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
#Component
#Qualifier("FireImpl1")
public class FireImpl1 implements Fire {
public void fire() {
System.out.println(getClass());
}
}
and dummy implementation 2
package spring;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
#Component
#Qualifier("FireImpl2")
public class FireImpl2 implements Fire {
public void fire() {
System.out.println(getClass());
}
}
config.xml
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context" xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
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
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
<context:component-scan base-package="spring" />
<bean id="bean1" class="spring.Bean1">
<property name="naber" value="nice" />
<property name="fire" ref="fireImpl2" />
</bean>
</beans>
and main class
package spring;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Spring {
public static void main(String[] args) {
ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("/spring/config.xml");
applicationContext.registerShutdownHook();
Bean1 bean = (Bean1) applicationContext.getBean("bean1");
System.out.println(bean.getNaber());
}
}
here is the output
init
class spring.FireImpl2
nice
destroy
Although annotation resolves dependency to FireImpl1, xml config overrided with FireImpl2.
very nice.

Answer 2

This should be OK. A Spring bean context allows you to redefine beans, with "later" definitions overriding "earlier ones". This should apply to XML-defined beans as well as annotation-defined beans, even if they're mixed.
For example, if you have
#Configuration
public class MyAnnotatedConfig {
#Bean
public Object beanA() {
...
}
}
<bean class="com.xyz.MyAnnotatedConfig"/>
<bean id="beanA" class="com.xyz.BeanA"/>
In this case, the XML definition of beanA should take precedence.