33-redis分布式缓存---缓存优化策略

/
/
/
/
/

package com.study.cache;

import com.study.util.ApplicationContextUtils;
import org.apache.ibatis.cache.Cache;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import org.springframework.util.DigestUtils;

//自定义redis缓存
public class RedisCache implements Cache {

    //当前放入缓存的mapper.xml文件的namespace
    private final String id;

    //必须存在一个构造方法
    public RedisCache(String id){
        this.id = id;
    }

    //返回cache的唯一标识
    @Override
    public String getId() {
        return this.id;
    }

    //缓存中放入值
    @Override
    public void putObject(Object key, Object value) {
        System.out.println("key:" + key.toString());
        System.out.println("value：" + value);

        //通过我们的ApplicationContextUtils类获取我们的RedisTemplate
        RedisTemplate redisTemplate = (RedisTemplate) ApplicationContextUtils.getBean("redisTemplate");
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());

        //我们使用我们redis的hash来存放我们的数据，因为key  hashKey   hashValue
        //key存放我们mapper的namespace，即我们这里的id     hashKey存放我们的数据的key，hashValue存放我们数据的值
        redisTemplate.opsForHash().put(id,getKeyToMd5(key.toString()),value);
    }

    //缓存中获取值
    @Override
    public Object getObject(Object key) {
        System.out.println("key: " + key);
        //获取我们的RedisTemplate
        RedisTemplate redisTemplate = (RedisTemplate) ApplicationContextUtils.getBean("redisTemplate");
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setKeySerializer(new StringRedisSerializer());

        return redisTemplate.opsForHash().get(id, getKeyToMd5(key.toString()));
    }

    //这个方法为mybatis的保留方法，以后可能会实现
    @Override
    public Object removeObject(Object key) {
        System.out.println("根据指定key删除缓存");
        return null;
    }

    @Override
    public void clear() {
        System.out.println("清空缓存");
        //获取我们的RedisTemplate
        RedisTemplate redisTemplate = (RedisTemplate) ApplicationContextUtils.getBean("redisTemplate");
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setKeySerializer(new StringRedisSerializer());

        //删除我们的id即namaspace即可
        redisTemplate.delete(id);
    }

    //用来计算缓存的数量
    @Override
    public int getSize() {
        //获取hash中key value数量
        return getRedisTemplate().opsForHash().size(id).intValue();
    }

    //获取我们的RedisTemplate
    private RedisTemplate getRedisTemplate(){
        RedisTemplate redisTemplate = (RedisTemplate) ApplicationContextUtils.getBean("redisTemplate");
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setKeySerializer(new StringRedisSerializer());

        return redisTemplate;
    }

    //对key进行md5加密
    private String getKeyToMd5(String key){
        String s = DigestUtils.md5DigestAsHex(key.getBytes());

        return s;
    }
}