Spring beans using annotation configuration

Learn to create spring beans using java configuration using annotations for any standalone application. We will learn to create it with and without scanning of component annotations and using @Bean annotations.

Table of contents

1. Annotation configuration with component scanning
2. Using @Bean and @Configuration annotations

1. Annotation configuration with component scanning

Creating beans using component scanning can be done in two steps.

1.1. Annotate beans with respective component annotations

We shall use use one of following four annotations as appropriate.

• @Component
• @Repository
• @Service
• @Controller

Read More: Spring Component Annotations

package com.howtodoinjava.spring.service.impl;

import org.springframework.stereotype.Service;
import com.howtodoinjava.spring.model.Employee;
import com.howtodoinjava.spring.service.EmployeeManager;

@Service
public class EmployeeManagerImpl implements EmployeeManager {

	@Override
	public Employee create() {
		Employee emp =  new Employee();
		emp.setId(1);
		emp.setName("Lokesh");
		return emp;
	}
}

1.2. Include bean packages in @ComponentScan annotation

@Configuration
@ComponentScan(basePackages = "com.howtodoinjava.spring.service")
public class AppConfig {
	
}

1.3. Demo

package com.howtodoinjava.spring;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import com.howtodoinjava.spring.model.Employee;
import com.howtodoinjava.spring.service.EmployeeManager;

public class Main 
{
    public static void main( String[] args )
    {
    	//Method 1
    	//ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
    	
    	//Method 2
    	AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        ctx.register(AppConfig.class);
        ctx.refresh();
        
    	EmployeeManager empManager = ctx.getBean(EmployeeManager.class);
    	Employee emp = empManager.create();
    	
    	System.out.println(emp);
    }
}

Program Output:

Employee [id=1, name=Lokesh]

2. Using @Bean and @Configuration annotations

To create spring application content using @Bean annotations, use these steps –

2.1. Create Java bean classes (no annotation or anything needed)

public class EmployeeManagerImpl implements EmployeeManager {

	@Override
	public Employee create() {
		Employee emp =  new Employee();
		emp.setId(1);
		emp.setName("Lokesh");
		return emp;
	}
}

2.2. Create @Bean annotation methods in configuration class

package com.howtodoinjava.spring;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import com.howtodoinjava.spring.service.EmployeeManager;
import com.howtodoinjava.spring.service.impl.EmployeeManagerImpl;

@Configuration
public class AppConfig {
	
    @Bean
    public EmployeeManager employeeManager() {
        return new EmployeeManagerImpl();
    }
	
}

2.3. Demo

package com.howtodoinjava.spring;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import com.howtodoinjava.spring.model.Employee;
import com.howtodoinjava.spring.service.EmployeeManager;

public class Main 
{
    public static void main( String[] args )
    {
    	//Method 1
    	//ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
    	
    	//Method 2
    	AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        ctx.register(AppConfig.class);
        ctx.refresh();
        
    	EmployeeManager empManager = ctx.getBean(EmployeeManager.class);
    	Employee emp = empManager.create();
    	
    	System.out.println(emp);
    }
}

Program Output:

Employee [id=1, name=Lokesh]

That’s pretty much two simple and easy ways to create spring beans using pure java code and annotations.

Happy Learning !!