Spring Boot @Bean

last modified July 6, 2020

In Spring Boot @Bean tutorial, we create a simple Bean in Spring Boot framework using the @Bean annotation.

Spring is a popular Java application framework and Spring Boot is an evolution of Spring which helps create stand-alone, production-grade Spring based applications with minimal effort.

Spring @Bean annotation

Spring @Bean annotation tells that a method produces a bean to be managed by the Spring container. It is a method-level annotation. During Java configuration (@Configuration), the method is executed and its return value is registered as a bean within a BeanFactory.

Spring Boot @Bean example

The core Spring container creates and manages beans. In the following application, we show how to create a Spring bean with the @Bean annotation. The application is command line Spring Boot application.

│   ├───java
│   │   └───com
│   │       └───zetcode
│   │               Application.java
│   │               AppName.java
│   └───resources
│           application.properties
│           logback.xml

This is the project structure of the Spring Boot application.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"









This is the Maven build file. The spring-boot-starter is the core starter that includes auto-configuration support, logging, and YAML. The application is packaged into a JAR file.

package com.zetcode;

interface AppName {

    String getName();

We have a simple interface that defines a contract. It is used to create an anonymous class that returns the application name.


The application.properties file contains application configuration settings. There are some built-in application properties and we can create our custom ones. The spring.main.banner-mode property is a Spring built-in property; we turn off the Spring's banner. With the spring.main.log-startup-info property, we can turn off the startup logging information. The app.name is our custom property that contains the application name.

<?xml version="1.0" encoding="UTF-8"?>
    <include resource="org/springframework/boot/logging/logback/base.xml" />
    <logger name="org.springframework" level="ERROR"/>
    <logger name="com.zetcode" level="INFO"/>

In the logback.xml file, we configure the application logging. We set the level of logging to ERROR. This way our output is not cluttered with unnecessary information. The spring-boot-starter dependency enables logback for logging.

package com.zetcode;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

public class Application implements CommandLineRunner {

    private static final Logger logger = LoggerFactory.getLogger(Application.class);

    private AppName appName;

    public AppName getAppName(@Value("${app.name}") String appName) {

        return () -> appName;

    public void run(String... args) throws Exception {

        logger.info("Application name: {}", appName.getName());

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);

In the Application, we create a bean, call its method and set up the Spring Boot application. The CommandLineRunner interface indicates that a bean should run when it is contained within a SpringApplication. It can be used to create command line applications in Spring Boot.

public class Application implements CommandLineRunner {

The @SpringBootApplication annotation enables auto-configuration and component scanning.

private AppName appName;

With the @Autowired annotation we inject our AppName bean into the field.

public AppName getAppName(@Value("${app.name}") String appName) {

    return () -> appName;

Here we create the AppName bean; the bean is managed by Spring container. While the @Component annotation is used to decorate classes that are auto-detected by Spring scanning, the @Bean annotation is used to explicitly declare a bean creation.

The @Value annotation is used to set the value of the app.name property into the appName parameter.

logger.info("Application name: {}", appName.getName());

We call the bean's getName() method.

We run the application with mvn -q spring-boot:run.

In this tutorial, we have created a Spring bean with the @Bean annotation.

List Spring Boot tutorials.