入口类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication; 
 
@SpringBootApplication
public class CenterApplication {

    public static void main(String[] args) {
        SpringApplication.run(CenterApplication.class, args);
    }

}

数据源配置类

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.type.JdbcType;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.sql.DataSource;

 
@EnableTransactionManagement
@Configuration
public class DruidConfig {
    private static final Logger logger = LoggerFactory.getLogger(DruidConfig.class); 

    @Bean
    public ServletRegistrationBean<StatViewServlet> druidServlet() {
        logger.info("init Druid Servlet Configuration ");
        ServletRegistrationBean<StatViewServlet> servletRegistrationBean = new ServletRegistrationBean<>(new StatViewServlet(), "/druid/*");
        // IP白名单
        servletRegistrationBean.addInitParameter("allow", "*");
        // IP黑名单(共同存在时，deny优先于allow)
        servletRegistrationBean.addInitParameter("deny", "192.168.1.111");
        //控制台管理用户
        servletRegistrationBean.addInitParameter("loginUsername", "admin");
        servletRegistrationBean.addInitParameter("loginPassword", "111111");
        //是否能够重置数据 禁用HTML页面上的“Reset All”功能
        servletRegistrationBean.addInitParameter("resetEnable", "false");
        return servletRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean<WebStatFilter> filterRegistrationBean() {
        FilterRegistrationBean<WebStatFilter> filterRegistrationBean = new FilterRegistrationBean<>(new WebStatFilter());
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
        return filterRegistrationBean;
    }

// @Primary 主数据必须写，不写会报错
    @Primary
    @Bean(name = "master") 
    public DataSource masterDataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://ip:port/xl_master?useUnicode=true&characterEncoding=utf-8&useSSL=false&autoReconnect=true&serverTimezone=Asia/Shanghai&allowMultiQueries=true");
        dataSource.setUsername("test");
        dataSource.setPassword("test");
        return dataSource;
    }


    @Bean(name = "db1") 
    public DataSource db1DataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://ip:port/db1?useUnicode=true&characterEncoding=utf-8&useSSL=false&autoReconnect=true&serverTimezone=Asia/Shanghai&allowMultiQueries=true");
        dataSource.setUsername("test");
        dataSource.setPassword("test");
        return dataSource;
    }

// 主数据源 sessionFactory @Primary 主数据必须写，不写会报错
    @Primary
    @Bean("masterSqlSessionFactory")
    public SqlSessionFactory masterSqlSessionFactory(@Qualifier("master") DataSource masterDataSource) throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
        sqlSessionFactory.setDataSource(masterDataSource);
       //master 对应的mapper xml 位置
        sqlSessionFactory.setMapperLocations(new 
PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml"));
        MybatisConfiguration configuration = new MybatisConfiguration();
        configuration.setJdbcTypeForNull(JdbcType.NULL);
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.setCacheEnabled(false);
        sqlSessionFactory.setConfiguration(configuration);
        //添加分页功能
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        sqlSessionFactory.setPlugins(interceptor);
        return sqlSessionFactory.getObject();
    }

// 主数据扫描器
    @Bean("masterMapperScanner")
    public MapperScannerConfigurer masterMapperScanner(@Qualifier("masterSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        MapperScannerConfigurer scanner = new MapperScannerConfigurer();
        scanner.setSqlSessionFactory(sqlSessionFactory);
      // 扫描包的路径
        scanner.setBasePackage("com.test.master");
        return scanner;
    }

// db1的 sessionFactory 
    @Bean("db1SqlSessionFactory")
    public SqlSessionFactory db1SqlSessionFactory(@Qualifier("db1") DataSource db1DataSource) throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
        sqlSessionFactory.setDataSource(db1DataSource);
 //master 对应的mapper xml 位置
        sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:db1/*.xml"));
        MybatisConfiguration configuration = new MybatisConfiguration();
        configuration.setJdbcTypeForNull(JdbcType.NULL);
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.setCacheEnabled(false);
        sqlSessionFactory.setConfiguration(configuration);
        //分页
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        sqlSessionFactory.setPlugins(interceptor);
        return sqlSessionFactory.getObject();
    }

    @Bean("db1MapperScanner")
    public MapperScannerConfigurer db1MapperScanner(@Qualifier("db1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        MapperScannerConfigurer scanner = new MapperScannerConfigurer();
        scanner.setSqlSessionFactory(sqlSessionFactory);
 // 包的路径
        scanner.setBasePackage("com.test.db1");
        return scanner;
    }
}

使用

使用不需要做任何调整，正常引入Mapper使用即可，这个方法是在mybatise plus 实例化mapper时，将数据源注入，这样mapper实例在创建的时候，就已经有对应的数据源了，不存在切换问题，也不存在资源竞争

缺点

因为MapperScanner 初始化的时间早于配置文件读取时间，所以配置只能用另外的文件，不能放在application.yml 里面