Spring @Configuration tutorial

last modified October 18, 2023

Spring @Configuration annotation tutorial shows how to configure Spring application using @Configuration annotation.

Spring is a popular Java application framework for creating enterprise applications.

Spring @Configuration

@Configuration annotation is used for Spring annotation based configuration. The @Configuration is a marker annotation which indicates that a class declares one or more @Bean methods and may be processed by the Spring container to generate bean definitions and service requests for those beans at runtime

Spring @Configuration example

The following application uses @Configuration to configure a Spring application.

    │   ├───java
    │   │   └───com
    │   │       └───zetcode
    │   │           │   Application.java
    │   │           └───config
    │   │                   AppConfig.java
    │   │                   H2Configurer.java
    │   └───resources
    │           application.properties
    │           logback.xml

This is the project structure.

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










In the pom.xml file, we have basic Spring dependencies spring-core, spring-context, and logging logback-classic dependency.

The exec-maven-plugin is used for executing Spring application from the Maven on the command line.

<?xml version="1.0" encoding="UTF-8"?>
    <logger name="org.springframework" level="ERROR"/>
    <logger name="com.zetcode" level="INFO"/>

    <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
            <Pattern>%d{HH:mm:ss.SSS} %blue(%-5level) %magenta(%logger{36}) - %msg %n

        <level value="INFO" />
        <appender-ref ref="consoleAppender" />

The logback.xml is a configuration file for the Logback logging library.

app.name=My application

Here we have some application properties.

package com.zetcode.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@ComponentScan(basePackages = "com.zetcode")
@PropertySource(value = "application.properties")
public class AppConfig {

    public H2Configurer databaseConfig() {
        return new H2Configurer();

AppConfig is the application configuration class. It is decorated with the @Configuration annotation, which is a specialization of the @Component.

@ComponentScan(basePackages = "com.zetcode")
@PropertySource(value = "application.properties")
public class AppConfig {

Component scanning is enabled with @ComponentScan and the resources are loaded with @PropertySource.

public H2Configurer databaseConfig() {
    return new H2Configurer();

With @Bean annotation, we create a H2Configurer bean.

package com.zetcode.config;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class H2Configurer {

    private static final Logger logger = LoggerFactory.getLogger(H2Configurer.class);

    public H2Configurer() {

        logger.info("Configuring H2 database");

The H2Configurer simply logs a message.

package com.zetcode;

import com.zetcode.config.AppConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.stereotype.Component;

public class Application {

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

    public static void main(String[] args) {

        var ctx = new AnnotationConfigApplicationContext(AppConfig.class);
        var app = ctx.getBean(Application.class);



    private String applicationName;

    private String database;

    private void run() {

        logger.info("Application name: {}", applicationName);
        logger.info("Database: {}", database);


The application class prints the application properties. The properties are injected into the attributes with @Value.

var ctx = new AnnotationConfigApplicationContext(AppConfig.class);

The AppConfig is loaded into the application context.

$ mvn -q exec:java
20:07:39.769 INFO  com.zetcode.config.H2Configurer - Configuring H2 database 
20:07:39.801 INFO  com.zetcode.Application - Application name: My application 
20:07:39.816 INFO  com.zetcode.Application - Database: H2 

We run the application.

In this article we have configured a Spring application with @Configuration.


My name is Jan Bodnar and I am a passionate programmer with many years of programming experience. I have been writing programming articles since 2007. So far, I have written over 1400 articles and 8 e-books. I have over eight years of experience in teaching programming.

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