SpringBoot配置多数据源

项目框架：SpringBoot + MyBatis + Mysql
项目连接两个数据库源。
1、application.yml配置

• 使用DruidDataSource
• 主数据库为primary，副数据库为secondary，名称可以自己定义，只要和后续的配置文件config相对应即可

spring:
  datasource:
      type: com.alibaba.druid.pool.DruidDataSource
      #druid相关配置
      druid:
        #监控统计拦截的filters
        filters: stat
        #配置初始化大小/最小/最大
        initial-size: 5
        min-idle: 5
        max-active: 100
        #获取连接等待超时时间
        max-wait: 60000
        #间隔多久进行一次检测，检测需要关闭的空闲连接
        time-between-eviction-runs-millis: 60000
        #一个连接在池中最小生存的时间
        min-evictable-idle-time-millis: 300000
        validation-query: SELECT 'x'
        test-while-idle: true
        test-on-borrow: false
        test-on-return: false
        #打开PSCache，并指定每个连接上PSCache的大小。oracle设为true，mysql设为false。分库分表较多推荐设置为false
        pool-prepared-statements: false
        max-pool-prepared-statement-per-connection-size: 20
      primary:
        driver-class-name: com.mysql.jdbc.Driver
        jdbc-url: jdbc:mysql://10.0.254.101:3306/test001?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&useSSL=false # 测试
        username: root
        password: 123456
      secondary:
        driver-class-name: com.mysql.jdbc.Driver
        jdbc-url: jdbc:mysql://10.0.254.102:3306/test001?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&useSSL=false # 测试
        username: root
        password: 123456

2、在config包下新增配置文件：PrimaryDataSourceConfig和SecondaryDataSourceConfig，结构如下：

PrimaryDataSourceConfig：

```java
@Configuration
@MapperScan(basePackages = "com.test.dao.primary", sqlSessionTemplateRef = "primarySqlSessionTemplate")
public class PrimaryDataSourceConfig {

    private static final String MAPPER_LOCATION = "classpath:mapper/primary/*.xml";

    @Bean(name = "primaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    @Primary
    public DataSource testDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "primarySqlSessionFactory")
    @Primary
    public SqlSessionFactory testSqlSessionFactory(@Qualifier("primaryDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        //设置mapper配置文件
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(MAPPER_LOCATION));
        return bean.getObject();
    }

    @Bean(name = "primaryTransactionManager")
    @Primary
    public DataSourceTransactionManager testTransactionManager(@Qualifier("primaryDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "primarySqlSessionTemplate")
    @Primary
    public SqlSessionTemplate testSqlSessionTemplate(@Qualifier("primarySqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

SecondaryDataSourceConfig：

@Configuration
@MapperScan(basePackages = "com.test.dao.secondary", sqlSessionTemplateRef = "secondarySqlSessionTemplate")
public class SecondaryDataSourceConfig {

    private static final String MAPPER_LOCATION = "classpath:mapper/secondary/*.xml";

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

    @Bean(name = "secondarySqlSessionFactory")
    public SqlSessionFactory testSqlSessionFactory(@Qualifier("secondaryDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        //设置mapper配置文件
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(MAPPER_LOCATION));
        return bean.getObject();
    }

    @Bean(name = "secondaryTransactionManager")
    public DataSourceTransactionManager testTransactionManager(@Qualifier("secondaryDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "secondarySqlSessionTemplate")
    public SqlSessionTemplate testSqlSessionTemplate(@Qualifier("secondarySqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

3、dao层文件结构如下所示，要分开来存放，因为上面配置了basePackages

StudentDao示例代码如下：
StudentDao：

@Repository
public interface StudentDao {
    int selectStudentById(Long id);
}

4、Mapper文件
结构如下，一样需要分文件夹，因为在上述配置文件中指定了mapper文件夹MAPPER_LOCATION ：

5、StudentMapper.xml文件示例：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.test.dao.primary.StudentDao">
    <select id="selectStudentById" parameterType="java.lang.Long"  resultType="com.test.entity.Student">
        select *
        from student
        where id = #{id}
    </select>
</mapper>