SPRING 3 javaconfig using annotation simple hello world example.....step by step

source:http://www.mkyong.com/spring3

Spring JavaConfig 

Now, see a full Spring JavaConfig example.

1. Directory Structure

See directory structure of this example.

2. Dependency Library

To use JavaConfig (@Configuration), you need to include CGLIB library. See dependencies :

 <!-- Spring 3 dependencies -->
 <dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-core</artifactId>
  <version>${spring.version}</version>
 </dependency>
 
 <dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-context</artifactId>
  <version>${spring.version}</version>
 </dependency>
 
 <!-- JavaConfig need this library -->
 <dependency>
  <groupId>cglib</groupId>
  <artifactId>cglib</artifactId>
  <version>2.2.2</version>
 </dependency>

3. Spring Bean

A simple bean.

package com.mkyong.hello;
 
public interface HelloWorld {
 
 void printHelloWorld(String msg);
 
}

package com.mkyong.hello.impl;
 
import com.mkyong.hello.HelloWorld;
 
public class HelloWorldImpl implements HelloWorld {
 
 @Override
 public void printHelloWorld(String msg) {
 
  System.out.println("Hello : " + msg);
 }
 
}

4. JavaConfig Annotation

Annotate with @Configuration to tell Spring that this is the core Spring configuration file, and define bean via @Bean.

package com.mkyong.config;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import com.mkyong.hello.HelloWorld;
import com.mkyong.hello.impl.HelloWorldImpl;
 
@Configuration
public class AppConfig {
 
    @Bean(name="helloBean")
    public HelloWorld helloWorld() {
        return new HelloWorldImpl();
    }
 
}

5. Run it

Load your JavaConfig class with AnnotationConfigApplicationContext.

package com.mkyong.core;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import com.mkyong.config.AppConfig;
import com.mkyong.hello.HelloWorld;
 
public class App {
 public static void main(String[] args) {
 
            ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
     HelloWorld obj = (HelloWorld) context.getBean("helloBean");
 
     obj.printHelloWorld("Spring3 Java Config");
 
 }
}

Output

Hello : Spring3 Java Config