examcloud-components/src/main/java/cn/com/qmth/examcloud/web/cache/RandomObjectRedisCache.java

package cn.com.qmth.examcloud.web.cache;

import org.apache.commons.lang3.StringUtils;
import org.assertj.core.util.Arrays;

import cn.com.qmth.examcloud.commons.exception.ExamCloudRuntimeException;
import cn.com.qmth.examcloud.web.redis.RedisClient;
import cn.com.qmth.examcloud.web.support.SpringContextHolder;

/**
 * 随机redis缓存
 *
 * @author WANGWEI
 * @date 2019年4月25日
 * @Copyright (c) 2018-? http://qmth.com.cn All Rights Reserved.
 * @param <T>
 */
public abstract class RandomObjectRedisCache<T extends RandomCacheBean> implements ObjectCache<T> {

	private RedisClient redisClient;

	private RedisClient getRedisClient() {
		if (null == redisClient) {
			redisClient = SpringContextHolder.getBean(RedisClient.class);
		}
		return redisClient;
	}

	protected abstract String getKeyPrefix();

	protected abstract int getTimeout();

	protected String buildKey(Object... keys) {
		String key = getKeyPrefix() + StringUtils.join(Arrays.asList(keys), '_');
		return key;
	}

	private T getFromCache(String key) {
		Object object = getRedisClient().get(key, Object.class);
		@SuppressWarnings("unchecked")
		T t = (T) object;
		return t;
	}

	@Override
	public T get(Object... keys) {
		String key = buildKey(keys);
		T t = getFromCache(key);

		if (null == t) {
			refresh(keys);
		}
		t = getFromCache(key);
		return t;
	}

	@Override
	public void remove(Object... keys) {
		String key = buildKey(keys);
		getRedisClient().delete(key);
	}

	@Override
	public void refresh(Object... keys) {
		String key = buildKey(keys);
		T t = null;
		try {
			t = loadFromResource(keys);
		} catch (Exception e) {
			throw new ExamCloudRuntimeException("fail to load data. key=" + key, e);
		}
		if (null != t) {
			getRedisClient().set(key, t, getTimeout());
		} else {
			getRedisClient().delete(key);
		}
	}

}