实现功能：
1： 配置两个数据源，根据不同的mapper路径使用不同的数据连接
2 ：使用Druid连接池
3：Druid 可监控多个数据源的sql执行操作

分析：

查看mybatis_spring_boot_stater中关于自动装配的类可知【如上图】，需要自定义实现SqlsessionFactory和SqlSessionTemplate的Bean，其中public SqlSessionFactory sqlSessionFactory(DataSource dataSource) 方法依赖于DataSource数据源。所以需要根据不同的数据源配置，自定义配置不同的数据源Bean。然后配置不同的数据源在实现含有SqlsessionFactory 和SqlSessionTemplate的配置。

1 导入依赖

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

  <dependencies>

<!--持久层框架mybatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.2</version>
            <exclusions>
                <!-- 排除默认的 HikariCP 数据源 -->
                <exclusion>
                    <groupId>com.zaxxer</groupId>
                    <artifactId>HikariCP</artifactId>
                </exclusion>
            </exclusions>
        </dependency>


<!--mysql连接-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>

<!--druid数据源-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.21</version>
        </dependency>

<!--监测-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
        </dependency>

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

    </dependencies>

2 application.yml

spring:
  datasource:
    first:
       password: Liuyifei@@
       username: root
       driver-class-name: com.mysql.cj.jdbc.Driver
       url:  jdbc:mysql://localhost:3306/face?useSSL=false&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8
    second:
       password: Liuyifei@@
       username: root
       driver-class-name: com.mysql.cj.jdbc.Driver
       url: jdbc:mysql://localhost:3306/project_guli?useSSL=false&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8

    #   设置druid连接池 通用配置
    druid:
          initial-size: 3
          max-active: 8
          max-wait: 60000
          test-on-borrow: false
          test-on-return: false
          test-while-idle: true
          min-evictable-idle-time-millis: 300000
          pool-prepared-statements: true
          max-pool-prepared-statement-per-connection-size: 20
          # 配置监控统计拦截的filters
          filters: stat,wall,slf4j
          filter:
            stat:
              enabled: true
              log-slow-sql: true
              slow-sql-millis: 5000

          stat-view-servlet:
            login-password: admin
            login-username: admin
            enabled: true
            allow: 10.157.147.149
            url-pattern: /druid/*
            reset-enable: fasle

          web-stat-filter:
            enabled: true
            session-stat-enable: true
            sessionStatMaxCount: 20
            url-pattern: /*
            exclusions: "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*"

3 编码配置Druid数据源

根据application.yml可知，分为数据连接的特殊配置和通用配置。根据springboot和Durid的整合可知，SpringBoot整合Druid数据源（实行监控功能）
spring框架会读取prefix 为spring.datasource.druid的一系列配置信息自动装载成为DruidDataSource的Bean，因此可将通用配置放在spring.datasource.druid下，非通用配置后续再通过setXXX（）进行设置

/**
 * @Author lyf
 * @Date 2023/2/16 - 09:40
 * @Description
 **/
@Data
@ConfigurationProperties(prefix = "spring.datasource.first")
public class FirstDataSourceProperties {

    private String username;
    private String password;
    private String url;
    private String driverClassName;
}

/**
 * @Author lyf
 * @Date 2023/2/16 - 10:11
 * @Description
 **/
@Data
@ConfigurationProperties(prefix = "spring.datasource.second")
public class SecondDataSourceProperties {

    private String username;
    private String password;
    private String url;
    private String driverClassName;
}

/**
 * @Author lyf
 * @Date 2023/2/15 - 16:48
 * @Description 多数据源配置
 * 启用Druid数据源的通用设置和区别配置类数据
 **/
@Configuration
@EnableConfigurationProperties({
        FirstDataSourceProperties.class,
        SecondDataSourceProperties.class
})
public class DatasourceConfiguration {

    FirstDataSourceProperties d1;
    SecondDataSourceProperties d2;
    public DatasourceConfiguration(FirstDataSourceProperties d1,SecondDataSourceProperties d2){
        this.d1=d1;
        this.d2=d2;
    }


    @ConfigurationProperties("spring.datasource.druid")
    @Primary
    @Bean
    public DruidDataSource firstDatasource(){
        //通过spring.datasource.druid 加载通用配置
        DruidDataSource source = new DruidDataSource();
        
        //设置数据源的特殊配置
        source.setUsername(d1.getUsername());
        source.setPassword(d1.getPassword());
        source.setUrl(d1.getUrl());
        source.setDriverClassName(d1.getDriverClassName());
        return source;
    }


    @ConfigurationProperties("spring.datasource.druid")
    @Bean
    public DruidDataSource secondDatasource(){
        //通过spring.datasource.druid 加载通用配置
        DruidDataSource source = new DruidDataSource();
        //设置数据源的特殊配置
        source.setUsername(d2.getUsername());
        source.setPassword(d2.getPassword());
        source.setUrl(d2.getUrl());
        source.setDriverClassName(d2.getDriverClassName());
        return source;   
    }

}

使用@ConfigurationProperties注解将配置信息与JavaBean进行绑定。
@EnableConfigurationProperties和@ConfigurationProperties的用法可参考我的上一篇文章 注解ConfigurationProperties、EnableConfigurationProperties的用法
当前配置中仅有数据源的连接信息不同，可通过DruidDataSource 的setXXX()方法进行属性的设定，如有其它的特殊的配置可根据application.yml的配置进行设定

4 Mybatis配置实现不同Mapper路径使用不同的数据源

/**
 * @Author lyf
 * @Date 2023/2/15 - 16:52
 * @Description
 * com.example.multimybatisdatasourcedemo.mapper.mapper1 下使用数据源1
 **/
@MapperScan(
        basePackages = "com.example.multimybatisdatasourcedemo.mapper.mapper1",
        sqlSessionFactoryRef = "sqlSessionFactoryPrimary",
        sqlSessionTemplateRef = "sqlSessionTemplatePrimary")
@Configuration
public class FirstMybatisConfiguration {

    private DataSource firstDatasource;

    /**
     * 构造函数，注入第一个数据源
     * @param firstDatasource
     */
    public FirstMybatisConfiguration(@Qualifier("firstDatasource") DataSource firstDatasource) {
        this.firstDatasource = firstDatasource;
    }

    @Bean
    public SqlSessionFactory sqlSessionFactoryPrimary() throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(firstDatasource);
        return bean.getObject();
    }

    @Bean
    public SqlSessionTemplate sqlSessionTemplatePrimary() throws Exception {
        return new SqlSessionTemplate(sqlSessionFactoryPrimary());
    }

}

/**
 * @Author lyf
 * @Date 2023/2/15 - 16:52
 * @Description
 * com.example.multimybatisdatasourcedemo.mapper.mapper2 下使用数据源2
 **/
@MapperScan(
        basePackages = "com.example.multimybatisdatasourcedemo.mapper.mapper2",
        sqlSessionFactoryRef = "sqlSessionFactorySecond",
        sqlSessionTemplateRef = "sqlSessionTemplateSecond")
@Configuration
public class SecondMybatisConfiguration {

    private DataSource secondDatasource;

    /**
     * 构造函数，注入第二个数据源
     * @param secondDatasource
     */
    public SecondMybatisConfiguration(@Qualifier("secondDatasource") DataSource secondDatasource) {
        this.secondDatasource = secondDatasource;
    }

    @Bean
    public SqlSessionFactory sqlSessionFactorySecond() throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(secondDatasource);
        return bean.getObject();
    }

    @Bean
    public SqlSessionTemplate sqlSessionTemplateSecond() throws Exception {
        return new SqlSessionTemplate(sqlSessionFactorySecond());
    }

}

能够做到多个数据源的关键点 就是每个数据源所扫描的mapper包不一样，谁扫描到哪个mapper那么该mapper就用哪个数据源,同时都扫到了，就用添加@Primary 的数据源。
用 @Primary 标志该 Bean。标志这个 Bean 如果在多个同类 Bean 候选时，该 Bean优先被考虑。本文抢到mybatis的配置，所以忽略Mapper的编写和Controller的代码编写