详解Redis缓存预热的实现方法

public abstract class AbstractCache {
    /**
     * 缓存
     */
    protected abstract void init();
    /**
     * 获取缓存
     *
     * @param <T>
     * @return
     */
    public abstract <T> T get();
    /**
     * 清理缓存
     */
    public abstract void clear();
    /**
     * 重新加载
     */
    public void reload() {
        clear();
        init();
    }
}

@Component
public class ApplicationContextUtil implements ApplicationContextAware {
    private static ApplicationContext applicationContext;
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        ApplicationContextUtil.applicationContext = applicationContext;
    }
    /**
     * 获取上下文
     * @return
     */
    public static ApplicationContext getContext() {
        return applicationContext;
    }
}

@Component
@ConditionalOnProperty(name = {"cache.init.enable"}, havingValue = "true", matchIfMissing = false)
public class CachePreheatHandler implements CommandLineRunner {
    /**
     * 缓存预热
     * @param args
     * @throws Exception
     */
    @Override
    public void run(String... args) throws Exception {
        ApplicationContext context = ApplicationContextUtil.getContext();
        Map<String, AbstractCache> beansOfType = context.getBeansOfType(AbstractCache.class);
        for (Map.Entry<String, AbstractCache> cacheEntry : beansOfType.entrySet()) {
            AbstractCache cache = context.getBean(cacheEntry.getValue().getClass());
            cache.init();
        }
    }
}

cache.init.enable=true

@Component
@RequiredArgsConstructor
public class NewsCache extends AbstractCache {
    private static final String NEWS_KEY = "news";
    private final RedisTemplate<String, Object> redisTemplate;
    private final NewsService newsService;
    @Override
    protected void init() {
        if (Boolean.FALSE.equals(redisTemplate.hasKey(NEWS_KEY))) {
            redisTemplate.opsForValue().set(NEWS_KEY, newsService.list(), 30, TimeUnit.MINUTES);
        }
    }
    @Override
    public <T> T get() {
        if (Boolean.FALSE.equals(redisTemplate.hasKey(NEWS_KEY))) {
            reload();
        }
        return (T) redisTemplate.opsForValue().get(NEWS_KEY);
    }
    @Override
    public void clear() {
        redisTemplate.delete(NEWS_KEY);
    }
}

@RestController
@RequestMapping("/news")
@RequiredArgsConstructor
public class NewsController {
    private final NewsCache newsCache;
    @GetMapping("/cache")
    public List<News> list() {
        return newsCache.get();
    }
}