1.什么是Redis

一个开源的使用C语言编写、遵守BSD协议、支持网络、可基于内存亦可持久化的日志型、Key-Value数据库，并提供多种语言的API。非关系型数据库，数据之间没有关系，数据存储在内存中
https://www.redis.net.cn
目前Redis支持的键值数据类型如下：

• 字符串类型 string
• 哈希类型 hash
• 列表类型 list
• 集合类型 set
• 有序集合类型 sortedset

Mac在src目录下：
启动服务：redis-server
交互操作：redis-cli

2.持久化 redis.conf中配置。

• RDB：在一定的间隔时间内，检测key的变化情况，然后持久化数据。默认方式。

# Save the DB on disk:
#
#   save <seconds> <changes>
#
#   Will save the DB if both the given number of seconds and the given
#   number of write operations against the DB occurred.
#
#   In the example below the behaviour will be to save:
#   after 900 sec (15 min) if at least 1 key changed
#   after 300 sec (5 min) if at least 10 keys changed
#   after 60 sec if at least 10000 keys changed
#
#   Note: you can disable saving completely by commenting out all "save" lines.
#
#   It is also possible to remove all the previously configured save
#   points by adding a save directive with a single empty string argument
#   like in the following example:
#
#   save ""

save 900 1
save 300 10
save 60 10000

• AOF：日志记录的方式，可以记录每一条命令的操作。可以每一次命令操作后，持久化数据。
  appendonly no（关闭aof） ——> appendonly yes（开启aof）

# AOF and RDB persistence can be enabled at the same time without problems.
# If the AOF is enabled on startup Redis will load the AOF, that is the file
# with the better durability guarantees.
#
# Please check http://redis.io/topics/persistence for more information.

appendonly no

# The name of the append only file (default: "appendonly.aof")

appendfilename "appendonly.aof"

# The fsync() call tells the Operating System to actually write data on disk
# instead of waiting for more data in the output buffer. Some OS will really flush
# data on disk, some other OS will just try to do it ASAP.
#
# Redis supports three different modes:
#
# no: don't fsync, just let the OS flush the data when it wants. Faster.
# always: fsync after every write to the append only log. Slow, Safest.
# everysec: fsync only one time every second. Compromise.
#
# The default is "everysec", as that's usually the right compromise between
# speed and data safety. It's up to you to understand if you can relax this to
# "no" that will let the operating system flush the output buffer when
# it wants, for better performances (but if you can live with the idea of
# some data loss consider the default persistence mode that's snapshotting),
# or on the contrary, use "always" that's very slow but a bit safer than
# everysec.
#
# More details please check the following article:
# http://antirez.com/post/redis-persistence-demystified.html
#
# If unsure, use "everysec".

# appendfsync always 每一次操作都进行持久化
appendfsync everysec 每隔一秒进行一次持久化
# appendfsync no 不进行持久化

3.应用场景

• 缓存（数据查询、短链接、新闻内容、商品内容等）
• 任务队列（秒杀，抢购）
• 榜单/排行榜
• 网站访问统计
• 数据过期处理（短信验证码过期）
• 分布式集群架构中的session分离
• 聊天室的在线好友列表

4.连接池

public class RedisUtils {

    private RedisUtils(){}

    private static JedisPool jedisPool = null;

    static {

        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(50);
        config.setMaxIdle(10);

        jedisPool = new JedisPool(config,"localhost",6379);
    }

    static public Jedis getRedis () {

        return jedisPool.getResource();
    }
}

5.示例：

//    https://www.redis.net.cn
//    https://mvnrepository.com/artifact/redis.clients/jedis
//    https://www.redis.net.cn/tutorial/3507.html
    @Test
    public void test1 () {

        RedisUtils.getRedis().set("oneKey","some thing");

        String oneValue = RedisUtils.getRedis().get("oneKey");
        //some thing
        System.out.println(oneValue);

        RedisUtils.getRedis().del("oneKey");

        RedisUtils.getRedis().hset("oneHashKey","name","zhangsan");

        String hNameValue = RedisUtils.getRedis().hget("oneHashKey","name");
        //zhangsan
        System.out.println(hNameValue);

        RedisUtils.getRedis().hdel("oneHashKey","name");

        //list,左侧添加,结果打印应该是cba,因为是依次添加
        RedisUtils.getRedis().lpush("oneListKey","a","b","c");
        //list,右侧添加
        RedisUtils.getRedis().rpush("oneListKey","a","b","c");

        //0到-1 查询所有
        List<String> oneListValues = RedisUtils.getRedis().lrange("oneListKey",0,-1);
        //[c, b, a, a, b, c]
        System.out.println(oneListValues);

        String rOne = RedisUtils.getRedis().rpop("oneListKey");
        //c
        System.out.println(rOne);

        RedisUtils.getRedis().sadd("oneSetKey","a","b","c");

        RedisUtils.getRedis().srem("oneSetKey","a");

        Set<String> oneSetValues = RedisUtils.getRedis().smembers("oneSetKey");
        //[c, b]
        System.out.println(oneSetValues);

        //有序set 一般用在排行榜

        RedisUtils.getRedis().zadd("oneSortedSetKey",100,"a");
        RedisUtils.getRedis().zadd("oneSortedSetKey",80,"b");
        RedisUtils.getRedis().zadd("oneSortedSetKey",90,"c");

        Set<String> oneSortedSetValues = RedisUtils.getRedis().zrange("oneSortedSetKey",0,-1);
        //[b, c, a] 按照score的数值从低到高排列的结果
        System.out.println(oneSortedSetValues);

        Double bScore = RedisUtils.getRedis().zscore("oneSortedSetKey","b");
        //80.0
        System.out.println(bScore);

        //插入一个key,过期时间10秒，一般用在 验证码
        RedisUtils.getRedis().setex("oneOverTimeKey",10,"oneOverTimeValue");

        //查询所有的键 指令 keys *
        RedisUtils.getRedis().keys("*");

        //获取指定key的类型 指令 type key
        RedisUtils.getRedis().type("oneHashKey");

        //删除指定key 指令 del key
        RedisUtils.getRedis().del("oneHashKey");

        //close() 关闭 归还到连接池中
    }