首先创建一个SpringWeb项目——dynamicdb（spring-boot2.5.7）

然后引入相关依赖lombok、swagger2、mybatis-plus，如下：

<?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 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>2.5.7</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.example</groupId><artifactId>dynamicdb</artifactId><version>0.0.1-SNAPSHOT</version><name>dynamicdb</name><description>dynamicdb</description><properties><java.version>8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>
​<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.28</version><scope>compile</scope></dependency><dependency><groupId>io.springfox</groupId><artifactId>springfox-swagger2</artifactId><version>2.9.2</version></dependency><dependency><groupId>io.springfox</groupId><artifactId>springfox-swagger-ui</artifactId><version>2.9.2</version></dependency><!-- mybatis-plus 依赖 --><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.4.2</version></dependency><dependency><groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!-- sqlSessionTemplate 依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!-- spring-boot dynamic 动态数据库依赖-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>dynamic-datasource-spring-boot-starter</artifactId>
<version>2.5.6</version>
</dependency>
<!-- druid 动态简易使用依赖 @DS("db1")-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.20</version>
</dependency>  
</dependencies>
​
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
​
</project>

然后在包dynamicdb下面创建controller、mapper、dbmodel， 然后在resource下面创建mapper文件夹及问题，如下图：

然后配置application，启用swagger2和添加mapper扫描，如下：

@EnableSwagger2 @Log4j2 @SpringBootApplication @MapperScan("com.example.dynamicdb.mapper") public class DynamicdbApplication { ​ public static void main(String[] args) { SpringApplication.run(DynamicdbApplication.class, args); } }

然后编辑resources下的application.yml，如下：

server:port: 8082servlet:context-path: /api
spring:servlet:multipart:max-file-size: 50MBmax-request-size: 50MBdatasource:dynamic: #使用动态数据库配置primary: db1 # 配置默认数据库datasource:db1: # 数据源1driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost/db1username: rootpassword: 1qaz!QAZdb2: # 数据源2driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost/db2username: rootpassword: 1qaz!QAZdruid:initial-size: 1max-active: 20min-idle: 1max-wait: 60000autoconfigure:exclude: com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure # 去除druid配置 
mybatis-plus:mapper-locations: classpath:mapper/*.xml #指定resources下的mapper文件夹下是存储映射XML的文件夹然后创建SqlSessionController，使用SqlSession来加载Mapper，代码如下：

@RestController
public class SqlSessionController {
​
​@Autowiredprivate SqlSession sqlSession;
​@GetMapping(value = "/SqlSession/normalSql")@ResponseBody@ApiOperation(value = "默认查询，从主数据库查询", notes = "当前配置的主数据是db1-primary: db1")public List<user> normalSql() {//读取第一个数据库的值UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<user> users = mapper.test();return users;}@GetMapping(value = "/SqlSession/data_from_db1")@ResponseBody@DS("db1")@ApiOperation(value = "从db1数据库查询数据", notes = "查询db1")public List<user> data_from_db1() {//读取第一个数据库的值UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<user> users = mapper.test();return users;}
​@GetMapping(value = "/SqlSession/data_from_db2")@ResponseBody@DS("db2")@ApiOperation(value = "从db2数据库查询数据", notes = "查询db2")public List<user> data_from_db2(Integer id) {//读取第二个数据库的值UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<user> users = mapper.test();return users;}
}

代码中使用 @DS("db1")来指定该接口内使用的数据库。

再创建一个MapperController，测试使用Mapper直接访问数据库，如下

@RestController
public class MapperController {
​@Autowiredprivate UserMapper userMapper;
​@GetMapping(value = "/Mapper/normalSql")@ResponseBody@ApiOperation(value = "使用Mapper查询，从主数据库查询", notes = "当前配置的主数据是db1-primary: db1")public List<user> normalSql() {//读取第一个数据库的值List<user> users = userMapper.test();return users;}
}