Redis系列之实现分布式自增主键

软件环境

• JDK 1.8
• SpringBoot 2.2.1
• Maven 3.2+
• Mysql 8.0.26
• redis 6.2.14
• Mybatis Plus 3.4.3.4
• 开发工具

• IntelliJ IDEA
• smartGit

一、实现原理

使用Redis来实现分布式的主键自增主要是依赖于Redis的INCR命令，调用INCR命令的对应key，其数值是实现递增加一，所以利用这个性质，将redis独立部署起来就可以实现分布式环境的自增ID，如图，使用INCR命令的例子

二、实践

本博客写一个基于redis、mybatis-plus的例子，主要介绍一下redis分布式ID的基本使用

首先，快速新建一个Spring Initializr项目，service url就选择这个https://start.aliyun.com，spring官网的url

选择jdk的版本，maven类型的项目

选择需要的依赖，选择之后，新生成的项目就会自动加上需要的maven配置，主要选择一下spring data redis的依赖

mybatis plus是没有搜到的，所以手动加一下

<dependency>
     <groupId>com.baomidou</groupId>
     <artifactId>mybatis-plus-boot-starter</artifactId>
     <version>3.4.3.4</version>
</dependency>
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
    <version>3.4.1</version>
</dependency>
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter-test</artifactId>
    <version>3.4.3.4</version>
</dependency>

项目pom.xml文件参考

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>springboot-redis</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-redis</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <mybatis.plus.version>3.4.3.4</mybatis.plus.version>
        <dynamic.datasource.version>3.4.1</dynamic.datasource.version>
        <mysql.connector.version>8.0.21</mysql.connector.version>
        <java.version>8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>${mybatis.plus.version}</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>${dynamic.datasource.version}</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter-test</artifactId>
            <version>${mybatis.plus.version}</version>
        </dependency>


        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.connector.version}</version>
        </dependency>

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.7.11</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

application.yml配置文件参考

spring:
  redis:
    host: 127.0.0.1
    port: 6379
    password:
    database: 0
  datasource:
    dynamic:
      primary: shop #设置默认的数据源或者数据源组,默认值即为master
      strict: false #严格匹配数据源,默认false. true未匹配到指定数据源时抛异常,false使用默认数据源
      datasource:
        shop:
          url: jdbc:mysql://127.0.0.1:3306/shop?useUnicode=true&characterEncoding=utf-8
          username: root
          password:
          driver-class-name: com.mysql.jdbc.Driver # 3.2.0开始支持SPI可省略此配置
          schema: classpath:db/schema-mysql.sql
          data: classpath:db/data-mysql.sql
      


mybatis-plus:
  type-aliases-package: com.example.redis.*.*.model
  mapper-locations: classpath*:mapper/*/*.xml
  global-config:
    db-config:
      logic-not-delete-value: 1
      logic-delete-value: 0
  configuration:
    map-underscore-to-camel-case: true
    default-statement-timeout: 60
    cache-enabled: true
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

自定义redis主键生成器RedisIdentifierGenerator

package com.example.redis.common.handlers;

import com.baomidou.mybatisplus.core.incrementer.IdentifierGenerator;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

/**
 * <pre>
 *      Redis分布式ID生成器
 * </pre>
 *
 * <pre>
 * @author nicky
 * 修改记录
 *    修改后版本:     修改人：  修改日期: 2023/11/07 14:18  修改内容:
 * </pre>
 */
@Component
public class RedisIdentifierGenerator implements IdentifierGenerator {

    @Resource
    private RedisTemplate redisTemplate;

    @Override
    public Number nextId(Object entity) {
        String key = entity.getClass().getName();
        return redisTemplate.opsForValue().increment(key);
    }

}

加一个baseDO类，type设置为type = IdType.ASSIGN_ID

package com.example.redis.model;


import com.baomidou.mybatisplus.annotation.*;
import lombok.Data;

import java.time.LocalDateTime;

@Data
public class BaseDO {


    @TableId(value = "id", type = IdType.ASSIGN_ID)
    private Long id;

    @TableField(value = "create_time", fill = FieldFill.INSERT)
    private LocalDateTime createTime;

    @TableField(value = "modify_time", fill = FieldFill.INSERT_UPDATE)
    private LocalDateTime modifyTime;

    @TableLogic(value = "0", delval = "1")
    @TableField(value = "is_deleted", select = false)
    private Boolean deleted;

}

写一个测试类，运行一下看看：

package com.example.redis.controller;

import cn.hutool.core.bean.BeanUtil;
import com.example.redis.common.rest.ResultBean;
import com.example.redis.model.UserDO;
import com.example.redis.model.dto.UserDto;
import com.example.redis.service.IUserService;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@RestController
@RequestMapping(value = "/api")
public class UserController {

    @Resource
    private IUserService userService;

    @PostMapping(value = "/user")
    public ResultBean<UserDO> save(@RequestBody UserDto userDto) {
        UserDO user = BeanUtil.copyProperties(userDto , UserDO.class);
        boolean flag = userService.save(user);
        if (flag) return ResultBean.ok(user);
        return ResultBean.badRequest("新增失败");
    }


}

查看控制台日志，可以看到自增的主键生成

存在redis里的主键