参考资料:

1. Spring Boot 2.x基础教程：MyBatis的多数据源配置

一. 配置文件

spring:
  datasource:
    # 数据源1
    primary:
      jdbc-url: jdbc:mysql://localhost/myblog?useUnicode=true&characterEncoding=utf-8
      username: root
      password: mysql
      driver-class-name: com.mysql.cj.jdbc.Driver
    # 数据源2
    secondary:
      jdbc-url: jdbc:mysql://localhost/pythonblog?useUnicode=true&characterEncoding=utf-8
      username: root
      password: mysql
      driver-class-name: com.mysql.cj.jdbc.Driver

⏹同时连接了Mysql中的两个数据库,myblog和pythonblog

二. 多数据源配置类

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 javax.sql.DataSource;

@Configuration
public class DataSourceConfiguration {

    // Primary注解是在没有指明使用哪个数据源的时候指定默认使用的主数据源
    @Primary
    @Bean("primaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    public DataSource primaryDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean("secondaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.secondary")
    public DataSource secondaryDataSource() {
        return DataSourceBuilder.create().build();
    }
}

三. 多数据源Mybatis配置

⭕注意事项:

• 3.1 primary数据源配置和3.2 secondary数据源配置是两种不同的配置方式,都能实现多数据源的效果.此处使用两种不同的方式进行配置,只是为了展示不同的配置方式.
• sqlSessionFactoryBean.setMapperLocations适用于Mybatis的Mapper接口文件和 .xml文件不在同一个目录下的情况,用于指定 .xml文件 所在的文件路径.
• @Primary注解用于指定默认的数据源.

3.1 primary数据源配置

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.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.annotation.Resource;
import javax.sql.DataSource;

@Configuration
@MapperScan(
		// 指定该数据源扫描指定包下面的Mapper接口文件
        basePackages = "com.example.jmw.mapper",
        sqlSessionFactoryRef = "sqlSessionFactoryPrimary",
        sqlSessionTemplateRef = "sqlSessionTemplatePrimary")
publc class DataSourcePrimaryConfig {
	
	// 注入数据源1
    @Resource
    private DataSource primaryDataSource;

    @Bean
    @Primary
    public SqlSessionFactory sqlSessionFactoryPrimary() throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(primaryDataSource);
        return sqlSessionFactoryBean.getObject();
    }

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

3.2 secondary数据源配置

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

@Configuration
@MapperScan(
        basePackages = "com.example.jmw.mapper1",
        sqlSessionFactoryRef = "sqlSessionFactorySecondary")
public class DataSourceSecondaryConfig {

    // mapper扫描xml文件的路径
    private static final String MAPPER_LOCATION = "classpath:mapper1/*.xml";

    private DataSource secondaryDataSource;
	
	// 通过构造方法进行注入
    public DataSourceSecondaryConfig(@Qualifier("secondaryDataSource") DataSource secondaryDataSource) {
        this.secondaryDataSource = secondaryDataSource;
    }

    @Bean
    public SqlSessionFactory sqlSessionFactorySecondary() throws Exception {

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();

        // 指定数据源
        sqlSessionFactoryBean.setDataSource(secondaryDataSource);
        /*
			获取xml文件资源对象
			当Mapper接口所对应的.xml文件与Mapper接口文件分离,存储在 resources 
			文件夹下的时候,需要手动指定.xml文件所在的路径
		*/ 
        Resource[] resources = new PathMatchingResourcePatternResolver().getResources(MAPPER_LOCATION);
        sqlSessionFactoryBean.setMapperLocations(resources);

        return sqlSessionFactoryBean.getObject();
    }

    @Bean
    public DataSourceTransactionManager SecondaryDataSourceManager() {
        return new DataSourceTransactionManager(secondaryDataSource);
    }
}

四. 效果

import com.example.jmw.mapper.I18nMessageMapper;
import com.example.jmw.mapper1.BlogTagMapper;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.annotation.Resource;
import java.util.List;

@Controller
@RequestMapping("/test12")
public class Test12Controller {
	
	// 数据源1Mapper注入
	@Resource
    private I18nMessageMapper i18nMessageMapper;
	
	// 数据源2Mapper注入
    @Resource
    private BlogTagMapper blogTagMapper;

    @GetMapping("/selectManyDataSourceData")
    @ResponseBody
    public void selectManyDataSourceData() {
		
		// 查询数据源1中的数据
        List<I18MessageEnttiy> allLocaleMessage = i18nMessageMapper.getAllLocaleMessage();
        System.out.println(allLocaleMessage);
		
		// 查询数据源2中的数据
        List<BlogTag> allBlogTag = blogTagMapper.getAllBlogTag();
        System.out.println(allBlogTag);
    }
}