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We have created two configuration files and now we will use @Import annotation toimport an AppConfiguration2file into a main AppConfigurationconfig file.

@Configuration
public class AppConfiguration2 {
 
 @Bean(name="twitterService")
 public MessageService twitterService(){
 return new TwitterService();
 }
 
 @Bean
 public MessageProcessor messageProcessor(){
 return new MessageProcessorImpl(twitterService());
 }
}

Let's create main app Java-based configuration class.

@Configuration
@ComponentScan("com.javadevsguide.springframework.di")
@Import(AppConfiguration2.class)
public class AppConfiguration {
 @Bean(name="emailService")
 public MessageService emailService(){
 return new EmailService();
 }
 
 @Bean(name="smsService")
 public MessageService smsService(){
 return new SMSService();
 }
}

Create MessageService interface and it's multiple implementations.

public interface MessageService {
 public void sendMsg(String message);
}

public class SMSService implements MessageService{
 public void sendMsg(String message) {
 System.out.println(message);
 }
}

public class EmailService implements MessageService{
 public void sendMsg(String message) {
 System.out.println(message);
 }
}

public class TwitterService implements MessageService{
 public void sendMsg(String message) {
 System.out.println(message);
 }
}

public interface MessageProcessor {
 public void processMsg(String message);
}

public class MessageProcessorImpl implements MessageProcessor {
 private MessageService messageService;
 @Autowired
 public MessageProcessorImpl(@Qualifier("TwitterService") MessageService messageService) {
 this.messageService = messageService;
 }
 public void processMsg(String message) {
 messageService.sendMsg(message);
 }
}

Let's test this application :

public class TestApplication {
 public static void main(String[] args) {
 ApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfiguration.class);
 MessageProcessor userService = applicationContext.getBean(MessageProcessor.class);
 userService.processMsg("twitter message sending ");
 }
}

Output:

twitter message sending 

>> Spring Java Based Configuration Basics
In this article, we will briefly look into basics of Spring Java-based container configuration.

>> Spring Java Based Configuration Example
In this post, we will demonstrate the usage of Spring Java-based container configuration.

>> Spring @Bean Annotation with Example
In this article, we will discuss Spring Java configuration based @Bean annotation with examples. We will also discuss different scenarios of how and when to use @Bean annotation.

>> Spring @Configuration Annotation with Example
In this article, we will discuss a very important Spring Java based configuration annotation that is a @Configuration annotation with examples.

>> Spring @Import Annotation with Example
In this article, we will discuss how to use Spring @Import annotation with examples.

>> Spring @ImportResource Annotation Example