Spring Java configuration lets you configure your application using Java classes instead of XML.
The main annotations are:
@Configuration— marks a class as a Spring configuration class@Bean— declares a Spring bean manually@ComponentScan— tells Spring where to find annotated components@PropertySource— loads external properties@Enable...annotations — enable specific Spring features, such as MVC, transactions, JPA, etc.
1. Create a configuration class
import org.springframework.context.annotation.Configuration;
@Configuration
public class AppConfig {
}
@Configuration tells Spring that this class contains bean definitions and application setup.
2. Define beans manually with @Bean
Use @Bean when you want Spring to manage an object that you create yourself.
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class AppConfig {
@Bean
public MyService myService() {
return new MyService();
}
}
Spring will create and manage the MyService instance.
By default, the bean name is the method name: myService.
3. Use component scanning
Instead of defining every bean manually, you can let Spring discover classes annotated with:
@Component@Service@Repository@Controller@RestController
Example:
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@Configuration
@ComponentScan("com.example.app")
public class AppConfig {
}
Then Spring can find beans like this:
import org.springframework.stereotype.Service;
@Service
public class MyService {
public void doWork() {
System.out.println("Working...");
}
}
4. Inject dependencies through constructors
Java configuration works together with dependency injection.
import org.springframework.stereotype.Repository;
@Repository
public class UserRepository {
public String findNameById(Long id) {
return "Alice";
}
}
import org.springframework.stereotype.Service;
@Service
public class UserService {
private final UserRepository userRepository;
public UserService(UserRepository userRepository) {
this.userRepository = userRepository;
}
public String getUserName(Long id) {
return userRepository.findNameById(id);
}
}
If both classes are discovered by component scanning, Spring automatically injects UserRepository into UserService.
5. Bootstrapping Spring manually
For a non-Spring Boot application, you can start the Spring container like this:
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext context =
new AnnotationConfigApplicationContext(AppConfig.class);
MyService myService = context.getBean(MyService.class);
myService.doWork();
}
}
6. Configure Spring MVC with Java configuration
For Spring MVC, use @EnableWebMvc and implement WebMvcConfigurer.
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
@EnableWebMvc
@ComponentScan("com.example.app")
public class WebConfig implements WebMvcConfigurer {
}
Example controller:
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@GetMapping("/hello")
public String hello() {
return "Hello from Spring MVC";
}
}
7. Load properties
You can load a properties file with @PropertySource.
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
@Configuration
@PropertySource("classpath:application.properties")
public class AppConfig {
}
Then inject values with @Value:
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component
public class AppInfo {
private final String appName;
public AppInfo(@Value("${app.name}") String appName) {
this.appName = appName;
}
}
Example application.properties:
app.name=My Spring App
8. Enable transactions
If you use database transactions, enable them with @EnableTransactionManagement.
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@EnableTransactionManagement
public class PersistenceConfig {
}
Then use @Transactional on services:
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
@Service
public class OrderService {
@Transactional
public void placeOrder() {
// database operations
}
}
Typical setup
A common Java configuration setup looks like this:
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@ComponentScan("com.example.app")
@PropertySource("classpath:application.properties")
@EnableTransactionManagement
public class AppConfig {
}
For Spring MVC:
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
@EnableWebMvc
@ComponentScan("com.example.app")
public class WebConfig implements WebMvcConfigurer {
}
Summary
To configure Spring using Java configuration:
- Create a class annotated with
@Configuration. - Add
@ComponentScanto discover annotated classes. - Use
@Beanmethods for manually created beans. - Use constructor injection for dependencies.
- Add feature-specific annotations such as
@EnableWebMvc,@EnableTransactionManagement, or JPA-related configuration as needed.
In most modern Spring applications, Java configuration plus component scanning replaces XML configuration almost entirely.