How to use Java to operate Redis database

Redis is a memory-based database that interacts with Redis to greatly improve the speed of operation.

First let us create a normal Maven project and add the corresponding dependencies

<dependencies>
		<dependency>
		    <groupId>redis.clients</groupId>
		    <artifactId>jedis</artifactId>
		    <version>3.3.0</version>
		</dependency>
		
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>fastjson</artifactId>
			<version>1.2.72</version>
		</dependency>
  </dependencies>

Then we can use

to test the connection (here I use the local reids service)

//定义主机号、端口号
		HostAndPort hostAndPort = new HostAndPort("127.0.0.1",6379);
		//连接redis服务
		Jedis jedis=new Jedis(hostAndPort);
		//ping一下
		System.out.println("服务正在运行: "+jedis.ping())
		//关闭
		jedis.close();

控制台输出PONG代表连接成功

Next let’s look at the basic operations of Redis’s five major data types

• String type

System.out.println("存入一个数据："+jedis.set("age", "20"));
		System.out.println("存入多个数据："+jedis.mset("name","zhangsan","sex","男"));
		
		System.out.println("获取一个数据："+jedis.get("age"));
		System.out.println("获取多个数据："+jedis.mget("name","sex"));
		
		System.out.println("将指定的字符串拼接在指定数据之后："+jedis.append("name","，你好"));
		
		System.out.println("查看某个数据的长度："+jedis.strlen("name"));
		
		System.out.println("修改某个数据的值并返回修改之前的值："+jedis.getSet("name", "lisi"));
		
		System.out.println("判断某个数据是否存在："+jedis.exists("name"));
		
		System.out.println("为某个数据设置失效时间（单位/s）："+jedis.expire("name", 20));
		
		System.out.println("查看某个数据的剩余生存时间(s)："+jedis.ttl("name"));
		
		System.out.println("删除一个或多个数据："+jedis.del("name","sex"));

View print results

• Set type

System.out.println("向集合添加一个或多个元素："+jedis.sadd("key1", "v1","v2","v3"));
		
		System.out.println("获取集合的元素个数："+jedis.scard("key1"));
		
		System.out.println("返回集合中的所有元素："+jedis.smembers("key1"));
		
		System.out.println("判断指定元素是否存在集合中："+jedis.sismember("key1", "v1"));
		
		System.out.println("移除集合中指定的元素："+jedis.srem("key1", "v3"));
		
		//这里我们在创建一个集合
		System.out.println("向集合添加一个或多个元素："+jedis.sadd("key2", "v2","v3","v4"));
		
		System.out.println("返回集合key1与key2的差集："+jedis.sdiff("key1","key2"));
		System.out.println("返回集合key1与key2的交集："+jedis.sinter("key1","key2"));
		System.out.println("返回集合key1与key2的并集："+jedis.sunion("key1","key2"));

View results

• Hash type

	Map map=new HashMap<>();
		map.put("name", "zhangsan");
		map.put("age", "20");
		map.put("sex", "男");
		
		System.out.println("创建一个哈希表存储一个用户对象："+jedis.hmset("user",map));
		
		System.out.println("获取哈希表中用户的name："+jedis.hget("user", "name"));
		
		System.out.println("查看哈希表中，指定的字段是否存在："+jedis.hexists("user", "name"));
		
		System.out.println("获取哈希表中字段的数量："+jedis.hlen("user"));
		
		System.out.println("获取哈希表中所有字段："+jedis.hkeys("user"));
		
		System.out.println("获取哈希表中所有字段的值："+jedis.hvals("user"));
		
		System.out.println("获取在哈希表中的所有字段和值："+jedis.hgetAll("user"));
		
		System.out.println("删除一个或多个哈希表字段："+jedis.hdel("user","name","age","sex"));

View results

• List type

System.out.println("将一个值插入到列表头部（可以多个值）："+jedis.lpush("city","北京","上海"));
		
		
		System.out.println("将一个值插入到列表尾部（可以多个值）："+jedis.rpush("city","济南","南京"));
		
		
		System.out.println("获取列表指定范围内的元素："+jedis.lrange("city", 0, -1));
		
		
		System.out.println("获取列表长度："+jedis.llen("city"));
		
		
		System.out.println("移出列表的第一个元素，并输出值："+jedis.lpop("city"));
		
		
		System.out.println("移除列表的最后一个元素，并输出值："+jedis.rpop("city"));
		
		
		System.out.println("修改列表中指定索引位置元素的值："+jedis.lset("city", 0, "西藏"));
		
		
		System.out.println("让列表只保留指定区间内的元素，不在指定区间之内的元素都将被删除："+jedis.ltrim("city", 1, 2));

View results

• Sorted Set type

Map<String,Double> scoreMembers=new HashMap<>();
		scoreMembers.put("member1", 1D);
		scoreMembers.put("member2", 2D);
		scoreMembers.put("member3", 3D);
		
		System.out.println("向有序集合添加一个或多个元素，或者更新已存在元素的分数："+jedis.zadd("member", scoreMembers));
		
		System.out.println("获取有序集合的元素个数："+jedis.zcard("member"));
		
		System.out.println("计算在有序集合中指定区间（[socre1,socre2]）分数的成员数："+jedis.zcount("member", 0D, 3D));
		
		System.out.println("通过索引区间返回有序集合指定区间内的元素，从低到高："+jedis.zrange("member", 0,-1));
		
		System.out.println("返回索引区间返回有序集合指定区间内的元素，从高到低："+jedis.zrevrange("member", 0,-1));
		
		System.out.println("返回有序集中指定元素的分数值："+jedis.zscore("member", "member1"));
		
		System.out.println("移除有序集合中的一个或多个元素："+jedis.zrem("member", "member1","member2"));
		
		System.out.println("返回有序集合中指定元素的索引："+jedis.zrank("member", "member3"));

View results

Finally we briefly look at how to operate the database

	System.out.println("清空当前数据库："+jedis.flushDB());
		
		System.out.println("清空所有数据库："+jedis.flushAll());
		
		System.out.println("查看当前数据库存储数据的多少："+jedis.dbSize());
		
		Set<String> keys = jedis.keys("*");
		System.out.println("查看当前数据库存储所有键值："+keys);
		
		System.out.println("选择某个数据库："+jedis.select(0));

View results

In fact, Redis also has three special storage types

• Geospatial                                                   

Mainly used to store geographical location information and operate on the stored information, based on Sorts Set ordered collection

• HyperLogLog
  

is used for cardinality statistics

• Bitmap
  

## records only two states by operating binary (0,1) Information

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