6.0 IoC using Java Annotations

What are Java Annotations ?

1. special labels/markers added to java class
2. provide meta-data about the class
3. Processed at compile time or run time

//below annotation will make sure that you are overriding the display method.

@Override

public void display()

{

    System.out.println("Hello World");

}

• Annotations minimizes the xml configurations.

Example

-----------------------------------------------------------------------------------------

BaseBallCoach.java

-----------------------------------------------------------------------------------------

package com.demo.spring;

import org.springframework.stereotype.Component;

@Component("MyCoach")

//instead of this we can use onl @Component then the bean id will be baseBallCoach

public class BaseBallCoach implements Coach {

@Override

public String getDailyWorkout() {

return "practice 30 mins daily";

}

}

-----------------------------------------------------------------------------------------

Coach.java

-----------------------------------------------------------------------------------------

package com.demo.spring;

public interface Coach {

public String getDailyWorkout();

}

-----------------------------------------------------------------------------------------

MyApp.java

-----------------------------------------------------------------------------------------

package com.demo.spring;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyApp {

public static void main(String[] args) {

ClassPathXmlApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");

Coach obj=context.getBean("MyCoach",Coach.class);

System.out.println(obj.getDailyWorkout());

context.close();

}

}

-----------------------------------------------------------------------------------------

applicationContext.xml

-----------------------------------------------------------------------------------------

<?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">

 <!-- initializing component scanning -->

 <context:component-scan base-package="com.demo.spring"></context:component-scan>

</beans>

-----------------------------------------------------------------------------------------

OUTPUT

-----------------------------------------------------------------------------------------

Feb 25, 2018 10:54:56 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@41975e01: startup date [Sun Feb 25 22:54:56 IST 2018]; root of context hierarchy

Feb 25, 2018 10:54:56 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

practice 30 mins daily

Feb 25, 2018 10:54:58 PM org.springframework.context.support.AbstractApplicationContext doClose

INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@41975e01: startup date [Sun Feb 25 22:54:56 IST 2018]; root of context hierarchy