<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-cache</artifactId>
</dependency>

public class Book {

private String isbn;
private String title;

public Book(String isbn, String title) {
 this.isbn = isbn;
 this.title = title;
}
….getter 
….setter

} 

public interface BookRepository {

 Book getByIsbn(String isbn);

}

@Component
public class SimpleBookRepository implements BookRepository {

 @Override

 public Book getByIsbn(String isbn) {
  simulateSlowService();
  return new Book(isbn, "Some book");
 }

 // Don't do this at home
 private void simulateSlowService() {
  try {
   long time = 3000L;
   Thread.sleep(time);
  } catch (InterruptedException e) {
   throw new IllegalStateException(e);
  }
 }

}

@Component
public class AppRunner implements CommandLineRunner {

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

 private final BookRepository bookRepository;

 public AppRunner(BookRepository bookRepository) {
  this.bookRepository = bookRepository;
 }

 @Override
 public void run(String... args) throws Exception {
  logger.info(".... Fetching books");
  logger.info("isbn-1234 -->" + bookRepository.getByIsbn("isbn-1234"));
  logger.info("isbn-4567 -->" + bookRepository.getByIsbn("isbn-4567"));
  logger.info("isbn-1234 -->" + bookRepository.getByIsbn("isbn-1234"));
  logger.info("isbn-4567 -->" + bookRepository.getByIsbn("isbn-4567"));
  logger.info("isbn-1234 -->" + bookRepository.getByIsbn("isbn-1234"));
  logger.info("isbn-1234 -->" + bookRepository.getByIsbn("isbn-1234"));
 }

}

2014-06-05 12:15:35.783 … : …. Fetching books

2014-06-05 12:15:40.783 … : isbn-1234 –> >Book{isbn='isbn-1234', title='Some book'}

2014-06-05 12:15:43.784 … : isbn-1234 –>Book{isbn='isbn-1234', title='Some book'}

2014-06-05 12:15:46.786 … : isbn-1234 –>Book{isbn='isbn-1234', title='Some book'}

@SpringBootApplication
@EnableCaching
public class DemoApplication {

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

@Component
public class SimpleBookRepository implements BookRepository {

 @Override
 @Cacheable("books")
 public Book getByIsbn(String isbn) {
  simulateSlowService();
  return new Book(isbn, "Some book");
 }

 // Don't do this at home
 private void simulateSlowService() {
  try {
   long time = 3000L;
   Thread.sleep(time);
  } catch (InterruptedException e) {
   throw new IllegalStateException(e);
  }
 }

}

isbn-1234 –>Book{isbn='isbn-1234', title='Some book'} 
2017-04-23 18:17:09.479 INFO 8054 — [ main] forezp.AppRunner : isbn-4567 –>Book{isbn='isbn-4567', title='Some book'} 
2017-04-23 18:17:09.480 INFO 8054 — [ main] forezp.AppRunner : isbn-1234 –>Book{isbn='isbn-1234', title='Some book'} 
2017-04-23 18:17:09.480 INFO 8054 — [ main] forezp.AppRunner : isbn-4567 –>Book{isbn='isbn-4567', title='Some book'} 
2017-04-23 18:17:09.481 INFO 8054 — [ main] forezp.AppRunner : isbn-1234 –>Book{isbn='isbn-1234', title='Some book'} 
2017-04-23 18:17:09.481 INFO 8054 — [ main] forezp.AppRunner : isbn-1234 –>Book{isbn='isbn-1234', title='Some book'}