1、配置文件

spring:
  datasource:
    db1:
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: root
      password: 123456
      url: jdbc:mysql://127.0.0.1:3306/db1?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
      type: com.alibaba.druid.pool.DruidDataSource
    db2:
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: root
      password: 123456
      url: jdbc:mysql://127.0.0.1:3306/db2?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
      type: com.alibaba.druid.pool.DruidDataSource

2、数据源配置类

2.1、DB1（主数据源使用@Primary）

package com.test.muchdb.datasource;

import com.alibaba.druid.pool.DruidDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
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.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "com.test.muchdb.mapper.db1",sqlSessionTemplateRef = "db1SqlSessionTemplate")
public class DataSource1Config {

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.db1")
    @Primary
    public DataSource db1DataSource() {
        return new DruidDataSource();
    }

    @Bean
    @Primary
    public SqlSessionFactory db1SqlSessionFactory(@Qualifier("db1DataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/db1/*.xml"));
        return bean.getObject();
    }

    @Bean
    @Primary
    public DataSourceTransactionManager db1TransactionManager(@Qualifier("db1DataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
    @Bean
    @Primary
    public SqlSessionTemplate db1SqlSessionTemplate(@Qualifier("db1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }

}

2.2、DB2

package com.test.muchdb.datasource;

import com.alibaba.druid.pool.DruidDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "com.test.muchdb.mapper.db2",sqlSessionTemplateRef = "db2SqlSessionTemplate")
public class DataSource2Config {

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.db2")
    public DataSource db2DataSource() {
        return new DruidDataSource();
    }

    @Bean
    public SqlSessionFactory db2SqlSessionFactory(@Qualifier("db2DataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/db2/*.xml"));
        return bean.getObject();
    }

    @Bean
    public DataSourceTransactionManager db2TransactionManager(@Qualifier("db2DataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean
    public SqlSessionTemplate db2SqlSessionTemplate(@Qualifier("db2SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }

}

3、提示

非主数据源必须要在@Transactional注解中指定数据源，否则事务不起作用。主数据库不需要。

@Transactional("db2TransactionManager")