引用: https://www.cnblogs.com/weigy/p/12857531.html

整体项目搭建：

数据源1：DataSource1Config

package com.test.config;

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.boot.jdbc.DataSourceBuilder;
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.mapper.db1", sqlSessionTemplateRef = "db1SqlSessionTemplate")
public class DataSource1Config {

    /**
     * 生成数据源.  @Primary 注解声明为默认数据源
     */
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.db1")
    @Primary
    public DataSource db1DataSource() {
//        return DataSourceBuilder.create().build();
        //要返回：return new DruidDataSource() 否则不使用Druid链接池
        return new DruidDataSource();
    }

    @Bean(name = "db1SqlSessionFactory")
    @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();
    }

    /**
     * 配置事务管理
     */
    @Primary
    @Bean(name = "db1TransactionManager")
    public DataSourceTransactionManager db1TransactionManager(@Qualifier("db1DataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "db1SqlSessionTemplate")
    @Primary
    public SqlSessionTemplate db1SqlSessionTemplate(@Qualifier("db1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }

}

数据源2： DataSource2Config

package com.test.config;

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.boot.jdbc.DataSourceBuilder;
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.mapper.db2", sqlSessionTemplateRef = "db2SqlSessionTemplate")
public class DataSource2Config {

    /**
     * 生成数据源.  @Primary 注解声明为默认数据源
     */
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.db2")
    @Primary
    public DataSource db2DataSource() {
//        return DataSourceBuilder.create().build();
        //要返回：return new DruidDataSource() 否则不使用Druid链接池
        return new DruidDataSource();
    }

    @Bean(name = "db2SqlSessionFactory")
    @Primary
    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();
    }

    /**
     * 配置事务管理
     */
    @Primary
    @Bean(name = "db2TransactionManager")
    public DataSourceTransactionManager db2TransactionManager(@Qualifier("db2DataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

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

}

application.properties

###DB1数据库####
spring.datasource.db1.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.db1.username=root
spring.datasource.db1.password=root
spring.datasource.db1.url=jdbc:mysql://192.1.177:3306/db1?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull
spring.datasource.db1.type=com.alibaba.druid.pool.DruidDataSource


######db2数据库#####
spring.datasource.db2.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.db2.username=root
spring.datasource.db2.password=root
spring.datasource.db2.url=jdbc:mysql://192.1.161.177:3306/db2?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull
spring.datasource.db2.type=com.alibaba.druid.pool.DruidDataSource

maven依赖：

 <dependency>
     <groupId>org.mybatis.spring.boot</groupId>
     <artifactId>mybatis-spring-boot-starter</artifactId>
     <version>2.1.2</version>
 </dependency>
 <dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>druid-spring-boot-starter</artifactId>
     <version>1.1.16</version>
 </dependency>
 <dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-web</artifactId>
 </dependency>