[Spring guide] Caching Data with Spring

https://spring.io/guides/gs/caching/

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틀린 해석이 있다면 알려주세요 💐

 

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github에 이미 소스가 아주 예쁘게 올라가 있어서 굳이 할 필요는 없지만 쭈욱 읽어보면서 핵심 기능들에 대한 코드를 정리해볼 생각이다

전체 파일 소스는 위의 출처 링크에서 깃허브로 들어가면 볼 수 있다

각 코드 부분에 대한 설명도 잘 적혀있어서 참고하기 좋았다

 

 

@SpringBootApplication is a convenience annotation that adds all of the following:

• @Configuration: Tags the class as a source of bean definitions for the application context.
• @EnableAutoConfiguration: Tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings. For example, if spring-webmvc is on the classpath, this annotation flags the application as a web application and activates key behaviors, such as setting up a DispatcherServlet.
• @ComponentScan: Tells Spring to look for other components, configurations, and services in the com/example package, letting it find the controllers.

 

You also need a CommandLineRunner that injects the BookRepository and calls it several times with different arguments. The following listing (from src/main/java/com/example/caching/AppRunner.java) shows that class:

Spring Boot Reference Documentation

 

 

 

 

package com.example.caching;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

@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"));
  }

}

 

캐싱을 사용하지 않을 경우 똑같은 요청에도 같은 데이터를 여러번 가져오게 된다

 

 

 

 

 

 

 

간단한 주석처리만으로 데이터 캐싱이 된다

package com.example.caching;

import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Component;

@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);
    }
  }

}

 

 

 

캐싱이 잘 관리되고 있는지 보려면 commandLineRunner 나 테스트를 아주 잘 작성할 필요가 있을 것 같다