Spring Annotation Configuration Example
This tutorial shows spring annotation configuration. Starting from Spring version 2.5, it is possible to configure bean dependency injection using annotations. So instead of using XML to describe a bean wiring, we can now use annotations to configure the bean wiring.
Creating a Service
First we create a simple service, which we’ll use in another bean to wire to that component.
package com.memorynotfound.spring;
public class Emperor {
public void kill(String name) {
System.out.println("Killing " + name);
}
}Injecting Bean with Spring annotation Configuration
We can use the @Autowired at method, constructor or field level to indicate that the component must be automatically injected by spring. This autowiring is not enabled by default, so before we can use the spring annotation configuration we will need to enable it in our spring configuration file.
package com.memorynotfound.spring;
import org.springframework.beans.factory.annotation.Autowired;
public class StarWars {
@Autowired
private Emperor emperor;
public void kill(String beans) {
emperor.kill(beans);
}
public void setEmperor(Emperor emperor) {
this.emperor = emperor;
}
}Enabling Spring Annotation Configuration
Because spring annotation configuration is not turned on by default we need to enable it. We do this by registering the <context:annotation-config/> element in the spring configuration file. This will enable annotation driven configuration. Next we define our 2 bean definitions so we can wire them together, like we did in the previous StarWars class.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<description>
This tutorial shows spring annotation configuration.
</description>
<context:annotation-config />
<bean class="com.memorynotfound.spring.StarWars"/>
<bean class="com.memorynotfound.spring.Emperor"/>
</beans>Running the application
We bootstrap the spring application using the ClassPathXmlApplicationContext and providing the Resource location of the spring configuration file.
package com.memorynotfound.spring;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Run {
public static void main(String... args){
ApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"app-config.xml"});
StarWars starWars = context.getBean(StarWars.class);
starWars.kill("Luke Skywalker");
}
}Demo
After running the application, it’ll produce the following output.
Killing Luke Skywalker
