Article directory
1. Principle
The core principle of implementing distributed auto-incrementing primary keys based on Redis is INCRthe command. Each call adds 1 to the digital value stored in the corresponding key, so it can easily implement auto-incrementing primary keys similar to Mysql databases.
Disadvantages : Only numeric primary keys are supported. If the cache is lost, the primary key will be duplicated.
[root@Mobile redis-stable]# redis-cli
127.0.0.1:6379> incr mycounter
(error) NOAUTH Authentication required.
127.0.0.1:6379> auth 123456
OK
127.0.0.1:6379> incr mycounter
(integer) 1
127.0.0.1:6379> incr mycounter
(integer) 2
127.0.0.1:6379>
Two, actual combat
The overall project still adoptsspring boot + mybaits-plus + mysql
For other content, please refer to: Mybatis-plus Snowflake Algorithm Generates Id Using Detailed Explanation
This article mainly replaces the default ID generator of the snowflake algorithm with a custom Redis distributed ID generator.
1. New redis dependency in maven
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
2. Redis connection attribute configuration
spring.redis.host=127.0.0.1
spring.redis.port=6379
spring.redis.password=123456
3. Customize Redis primary key generator RedisIdentifierGenerator
@Component
public class RedisIdentifierGenerator implements IdentifierGenerator{
@Resource
RedisTemplate redisTemplate;
@Override
public Number nextId(Object entity) {
//可以将当前传入的class全类名来作为bizKey,或者提取参数来生成bizKey进行分布式Id调用生成.
String bizKey = entity.getClass().getName();
//根据bizKey调用分布式ID生成
return redisTemplate.opsForValue().increment(bizKey);
}
}
4. Specify the generation strategy of the primary key idIdType.ASSIGN_ID
@TableName(value ="user")
@Data
@EqualsAndHashCode
public class User implements Serializable {
/**
* 主键ID
*/
@TableId(value = "id",type = IdType.ASSIGN_ID)
//@TableId(value = "id",type = IdType.AUTO)
private Long id;
/**
* 姓名
*/
private String name;
/**
* 年龄
*/
private Integer age;
/**
* 邮箱
*/
private String email;
@TableField(exist = false)
private static final long serialVersionUID = 1L;
}
5. Test
@Test
public void testInsert() {
System.out.println("----- insert method test ------");
User user = new User();
user.setName("test");
user.setAge(13);
user.setEmail("[email protected]");
userMapper.insert(user);
System.out.println(user.toString());
}
The primary key id is 1 assigned by RedisIdentifierGenerator
