SpringBoot 3.x+Mybatis Plus多数据源极简配置

1. 创建项目

创建一个名为mybatis-plus-demo的项目，使用Maven+JDK17。不会的请看 IntelliJ IDEA快速创建Spring Boot项目，最终项目结构，如下图。

2. 编写代码

根据最终项目结构，从下往上依次列出各个文件的代码。

2.1 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>mybatis-plus-demo</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><!--  为Spring Boot项目提供一系列默认的配置和依赖管理--><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>3.3.2</version><relativePath/></parent><dependencies><!--  Spring Boot核心依赖--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><!-- Spring Boot单元测试和集成测试的依赖--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><!-- Spring Boot构建Web应用程序的依赖--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!-- mysql驱动--><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId></dependency><!-- mybatis-plus核心依赖--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-spring-boot3-starter</artifactId><version>3.5.7</version></dependency><!--  动态数据源依赖--><dependency><groupId>com.baomidou</groupId><artifactId>dynamic-datasource-spring-boot3-starter</artifactId><version>4.3.1</version></dependency></dependencies></project>

2.2 application.properties

# 默认的数据源
spring.datasource.dynamic.primary=master
# 严格匹配数据源,默认false
spring.datasource.dynamic.strict=false
# 取消druid自动配置
spring.autoconfigure.exclude=com.alibaba.druid.spring.boot3.autoconfigure.DruidDataSourceAutoConfigure# 主库
spring.datasource.dynamic.datasource.master.url=jdbc:mysql://127.0.0.1:33066/test
spring.datasource.dynamic.datasource.master.username=root
spring.datasource.dynamic.datasource.master.password=123456
# 从库
spring.datasource.dynamic.datasource.slave.url=jdbc:mysql://127.0.0.1:33067/test
spring.datasource.dynamic.datasource.slave.username=root
spring.datasource.dynamic.datasource.slave.password=123456
#显示sql
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

2.3 mapper/UserMapperSlave.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.example.mapper.UserMapperSlave"><select id="selectAllPage" parameterType="java.util.Map" resultType="java.util.Map">select * from t_user_a<where><if test="param.name != null and param.name != ''">INSTR(CONCAT(IFNULL(name,'')),#{param.name})>0</if></where></select></mapper>

2.4 org/example/Main.java

package org.example;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.transaction.annotation.EnableTransactionManagement;@EnableTransactionManagement // 启用事务管理
@MapperScan("org.example.mapper") // 扫描mapper
@SpringBootApplication
public class Main {public static void main(String[] args) {SpringApplication.run(Main.class, args);}}

2.5 org/example/mapper/UserMapperSlave.java

注意@DS(“slave”)注解，与配置文件中数据源名称相对应

package org.example.mapper;import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.annotations.Param;
import org.example.entity.User;import java.util.List;
import java.util.Map;@DS("slave")
public interface UserMapperSlave extends BaseMapper<User> {@MapKey("")List<Map<String, Object>> selectAllPage(Page<?> page, @Param("param") Map<String, Object> param);
}

2.6 org/example/mapper/UserMapperMaster.java

package org.example.mapper;import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.example.entity.User;@DS("master")
public interface UserMapperMaster extends BaseMapper<User> {}

2.7 org/example/entity/User.java

package org.example.entity;import com.baomidou.mybatisplus.annotation.*;import java.util.Date;@TableName("t_user_a")
public class User {@TableId(type = IdType.ASSIGN_ID)private Long id;private String name;private String phone;@TableField(fill = FieldFill.INSERT)private Date createTime;@TableField(fill = FieldFill.INSERT_UPDATE)private Date updateTime;public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getPhone() {return phone;}public void setPhone(String phone) {this.phone = phone;}public Date getCreateTime() {return createTime;}public void setCreateTime(Date createTime) {this.createTime = createTime;}public Date getUpdateTime() {return updateTime;}public void setUpdateTime(Date updateTime) {this.updateTime = updateTime;}}

2.8 org/example/controller/UserController.java

package org.example.controller;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.example.entity.User;
import org.example.mapper.UserMapperMaster;
import org.example.mapper.UserMapperSlave;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;@Controller
@RequestMapping("/UserController")
public class UserController {@Autowiredprivate UserMapperMaster userMapperMaster;@Autowiredprivate UserMapperSlave userMapperSlave;@RequestMapping(value = "/insertMaster")@ResponseBody@Transactionalpublic Object insertMaster() {for (int i = 0; i < 20; i++) {User user = new User();user.setName("张"+i);user.setPhone(new Date().getTime()+"");userMapperMaster.insert(user);}return "数据插入成功";}@RequestMapping(value = "/listAllMaster")@ResponseBodypublic Object listAllMaster() {QueryWrapper<User> q = new QueryWrapper<>();q.like("name", "张1");List<User> list = userMapperMaster.selectList(q);return list;}@RequestMapping(value = "/listAllSlave")@ResponseBodypublic Object listAllSlave() {QueryWrapper<User> q = new QueryWrapper<>();q.like("name", "张1");List<User> list = userMapperSlave.selectList(q);return list;}@RequestMapping(value = "/listPageSlave")@ResponseBodypublic Object listPageSlave() {Page<?> page = new Page<>(1, 3);Map<String, Object> param = new HashMap<>();param.put("name", "张");List<Map<String, Object>> list = userMapperSlave.selectAllPage(page, param);return list;}}

2.9 org/example/conf/MyMetaObjectHandler.java

package org.example.conf;import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;import java.util.Date;/*MyBatis-Plus 提供了一个便捷的自动填充功能，用于在插入或更新数据时自动填充某些字段，如创建时间、更新时间等*/
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {@Overridepublic void insertFill(MetaObject metaObject) {this.setFieldValByName("createTime", new Date(), metaObject);this.setFieldValByName("updateTime", new Date(), metaObject);}@Overridepublic void updateFill(MetaObject metaObject) {this.setFieldValByName("updateTime", new Date(), metaObject);}
}

3.0 org/example/conf/MybatisPlusConfig.java

package org.example.conf;import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;/*MyBatis-Plus 配置*/
@Configuration
public class MybatisPlusConfig {/*** 添加分页插件*/@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor() {MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));return interceptor;}}

3. 测试

3.1 创建表

分别在两个数据库创建表t_user_a。

-- test.t_user_a definitionCREATE TABLE `t_user_a` (`id` bigint(20) NOT NULL,`name` varchar(255) DEFAULT NULL,`phone` varchar(255) DEFAULT NULL,`create_time` datetime DEFAULT NULL,`update_time` datetime DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

3.2 master插入数据

启动项目，然后访问：http://localhost:8080/UserController/insertMaster，可以看到master数据库已经插入成功。

3.3 slave查询数据

访问：http://localhost:8080/UserController/listAllSlave，可以看到从slave数据库查询出来的数据。由于我这里做了MySQL主从复制，因此没有手动往slave添加数据，您可以自行插入几条数据测试。不会MySQL主从复制的请看MySQL主从复制。

INSERT INTO test.t_user_a
(id, name, phone, create_time, update_time)
VALUES(0, '张1', '1724409931630', '2024-08-23 18:45:31', '2024-08-23 18:45:31');