常规思路：

package com.macro.mall.controller;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;

public class TestRedis2 {
    @Autowired
    private RedisTemplate redisTemplate;
    
    public void test(){
        long l = System.currentTimeMillis();
        String redisTestLongKey = "test-long-key";
        redisTemplate.opsForValue().set(redisTestLongKey,l);
        long o = (long) redisTemplate.opsForValue().get(redisTestLongKey);
        System.out.println(o);
    }
    
}

运行之后报错：Integer 不能转化为Long。

优化思路：

package com.macro.mall.controller;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;

public class TestRedis2 {
    @Autowired
    private RedisTemplate redisTemplate;

    public void test(){
        long l = System.currentTimeMillis();
        String redisTestLongKey = "test-long-key";
        redisTemplate.opsForValue().set(redisTestLongKey,l);
        Object obj =  redisTemplate.opsForValue().get(redisTestLongKey);
        Long result = null;
        if (obj instanceof Integer){
            result = ((Integer)obj).longValue();
        }else {
            result = (Long) obj;
        }
        System.out.println(result);
    }

}

总结：reids在存入long类型时，会转为int类型，导致在从reids中取值时int转long类型报错。

因此在取值时，做下类型特殊转换即可。