基于springboot多数据源的启动器

一、简述

dynamic-datasource-spring-boot-starter 是一个基于springboot的快速集成多数据源的启动器。其支持 Jdk 1.7+, SpringBoot 1.4.x 1.5.x 2.x.x。

二、准备数据

多数据源适用于多种场景例如：纯粹多库、 读写分离、 一主多从、 混合模式等。这里模拟一个多个库的一个场景，其他场景类似，场景说明：

• 创建两个库，分别为：mydb（以前的库不动）与mybatis_plus（新建）
• 在mydb库创建t_user表，在mybatis_plus库创建表t_product，这样保持每个库一张表，通过一个测试用例分别获取用户数据与商品数据，如果获取到说明多库模拟成功

创建表：

CREATE TABLE `t_product` (
  `id` bigint(20) NOT NULL COMMENT '主键ID',
  `NAME` varchar(30) DEFAULT NULL COMMENT '商品名称',
  `price` int(11) DEFAULT '0' COMMENT '价格',
  `VERSION` int(11) DEFAULT '0' COMMENT '乐观锁版本号',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `t_user` (
  `uid` bigint(20) NOT NULL DEFAULT '0' COMMENT '主键ID',
  `user_name` varchar(30) DEFAULT NULL COMMENT '姓名',
  `age` int(11) DEFAULT NULL COMMENT '年龄',
  `sex` int(11) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL COMMENT '邮箱',
  `is_delete` int(255) DEFAULT '0',
  PRIMARY KEY (`uid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

三、环境搭建

创建一个新的springboot项目

3.1.在pom.xml中引入依赖

 <!--lombok依赖-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
            <scope>provided</scope>
        </dependency>

        <!--引入多数据源驱动-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>3.5.0</version>
        </dependency>

        <!--mybatis-plus启动器-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.2</version>
        </dependency>

        <!--MySQL数据库连接的依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>

3.2.在application.yml中配置多数据源

spring:
  datasource:
    dynamic:
      primary: master #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:
        master:
          url: jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
          username: root
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver # 3.2.0开始支持SPI可省略此配置
        slave_1:
          url: jdbc:mysql://127.0.0.1:3306/mybatis_plus?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
          username: root
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver

3.3.在com.augus.pojo下创建实体类

package com.augus.pojo;

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

@AllArgsConstructor
@NoArgsConstructor
@Data
@TableName("t_user")
public class User implements Serializable {
    //指定id对应的表中主键字段为uid，主键策略为自增
    //@TableId(value = "uid", type = IdType.AUTO)
    @TableId(value = "uid")
    private Long id;
    @TableField(value = "user_name")
    private String name;
    private Integer age;
    private Integer sex;
    private String email;
    private Integer is_delete;
}

package com.augus.pojo;

import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.annotation.Version;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

@AllArgsConstructor
@NoArgsConstructor
@Data
@TableName("t_product")
public class Product implements Serializable {
    private Long id;
    private String name;
    private Integer price;
    private Integer version;
}

3.4.在com.augus.service下创建接口和实现类

 userservice

package com.augus.service;

import com.augus.pojo.User;
import com.baomidou.mybatisplus.extension.service.IService;

//这里接口需要基础IService,泛型需要指定对应的实体类
public interface UserSerivce extends IService<User> {
}

package com.augus.service.impl;

import com.augus.mapper.UserMapper;
import com.augus.pojo.User;
import com.augus.service.UserSerivce;
import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;


@Service
@DS("master") //指定所操作的数据源
public class UserServiceImpl extends ServiceImpl<UserMapper,User> implements UserSerivce {
}

ProductService

package com.augus.service;

import com.augus.pojo.Product;
import com.baomidou.mybatisplus.extension.service.IService;

public interface ProductService extends IService<Product> {
}

package com.augus.service.impl;

import com.augus.mapper.ProductMapper;
import com.augus.pojo.Product;
import com.augus.service.ProductService;
import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;


@Service
@DS("slave_1")
public class ProductServiceImpl extends ServiceImpl<ProductMapper, Product> implements ProductService {

}

四、创建测试类

创建测试，代码如下：

package com.augus;

import com.augus.service.ProductService;
import com.augus.service.UserSerivce;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class MybatisPlusDynamicDataSource {
    @Autowired
    private UserSerivce userSerivce;

    @Autowired
    private ProductService productService;

    @Test
    public void testDynamicDataSource(){
        //分别从user表和product表中获取数据
        System.out.println(userSerivce.getById(1598884966689693697L));
        System.out.println(productService.getById(1));
    }
}

执行后，结果如下，可以使用多个数据源从两个表中读取数据：