Spring Boot MyBatis配置Druid多数据源

回顾在Spring中配置MyBatis SqlSessionFactory的配置：

<!-- mybatis 的SqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean" scope="prototype">
    <property name="dataSource" ref="dataSource"/>
    <property name="configLocation" value="classpath:mybatis-config.xml"/>
</bean>

所以实际上在Spring Boot中配置MyBatis多数据源的关键在于创建SqlSessionFactory的时候为其分配不同的数据源。

引入依赖

先根据https://mrbird.cc/%E5%BC%80%E5%90%AFSpring-Boot.html开启一个最简单的Spring Boot应用，然后引入如下依赖：

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.1</version>
</dependency>

<!-- oracle驱动 -->
<dependency>
    <groupId>com.oracle</groupId>
    <artifactId>ojdbc6</artifactId>
    <version>6.0</version>
</dependency>

<!-- mysql驱动 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

<!-- druid数据源驱动 -->
<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>druid-spring-boot-starter</artifactId>
   <version>1.1.6</version>
</dependency>

多数据源配置

在Spring Boot配置文件application.yml中配置多数据源和Spring Boot JdbcTemplate配置Druid多数据源一致。

然后根据application.yml创建两个数据源配置类MysqlDatasourceConfig和OracleDatasourceConfig：

MysqlDatasourceConfig：

@Configuration
@MapperScan(basePackages = MysqlDatasourceConfig.PACKAGE, sqlSessionFactoryRef = "mysqlSqlSessionFactory")
public class MysqlDatasourceConfig {

    // mysqldao扫描路径
    static final String PACKAGE = "com.springboot.mysqldao";
    // mybatis mapper扫描路径
    static final String MAPPER_LOCATION = "classpath:mapper/mysql/*.xml";
    
    @Primary
    @Bean(name = "mysqldatasource")
    @ConfigurationProperties("spring.datasource.druid.mysql")
    public DataSource mysqlDataSource() {
        return DruidDataSourceBuilder.create().build();
    }
    
    @Bean(name = "mysqlTransactionManager")
    @Primary
    public DataSourceTransactionManager mysqlTransactionManager() {
        return new DataSourceTransactionManager(mysqlDataSource());
    }
    
    @Bean(name = "mysqlSqlSessionFactory")
    @Primary
    public SqlSessionFactory mysqlSqlSessionFactory(@Qualifier("mysqldatasource") DataSource dataSource)
            throws Exception {
        final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        sessionFactory.setDataSource(dataSource);
        //如果不使用xml的方式配置mapper，则可以省去下面这行mapper location的配置。
        sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources(MysqlDatasourceConfig.MAPPER_LOCATION));
        return sessionFactory.getObject();
    }
}

上面代码配置了一个名为mysqldatasource的数据源，对应application.yml中spring.datasource.druid.mysql前缀配置的数据库。然后创建了一个名为mysqlSqlSessionFactory的Bean，并且注入了mysqldatasource。与此同时，还分别定了两个扫描路径PACKAGE和MAPPER_LOCATION，前者为Mysql数据库对应的mapper接口地址，后者为对应的mapper xml文件路径。

@Primary标志这个Bean如果在多个同类Bean候选时，该Bean优先被考虑。多数据源配置的时候，必须要有一个主数据源，用@Primary标志该Bean。

同理，接着配置Oracle数据库对应的配置类：

OracleDatasourceConfig：

@Configuration
@MapperScan(basePackages = OracleDatasourceConfig.PACKAGE, 
    sqlSessionFactoryRef = "oracleSqlSessionFactory")
public class OracleDatasourceConfig {
	
    // oracledao扫描路径
    static final String PACKAGE = "com.springboot.oracledao"; 
    // mybatis mapper扫描路径
    static final String MAPPER_LOCATION = "classpath:mapper/oracle/*.xml";
    
    @Bean(name = "oracledatasource")
    @ConfigurationProperties("spring.datasource.druid.oracle")
    public DataSource oracleDataSource() {
        return DruidDataSourceBuilder.create().build();
    }
    
    @Bean(name = "oracleTransactionManager")
    public DataSourceTransactionManager oracleTransactionManager() {
        return new DataSourceTransactionManager(oracleDataSource());
    }
    
    @Bean(name = "oracleSqlSessionFactory")
    public SqlSessionFactory oracleSqlSessionFactory(@Qualifier("oracledatasource") DataSource dataSource) 
          throws Exception {
        final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        sessionFactory.setDataSource(dataSource);
        //如果不使用xml的方式配置mapper，则可以省去下面这行mapper location的配置。
        sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources(OracleDatasourceConfig.MAPPER_LOCATION));
        return sessionFactory.getObject();
    }
}

测试

配置完多数据源，接下来分别在com.springboot.mysqldao路径和com.springboot.oracledao路径下创建两个mapper接口：

MysqlStudentMapper：

package com.springboot.mysqldao;

import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface MysqlStudentMapper {
    List<Map<String, Object>> getAllStudents();
}

OracleStudentMapper：

package com.springboot.oracledao;

import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface OracleStudentMapper {
    List<Map<String, Object>> getAllStudents();
}

接着创建mapper接口对应的实现：

在src/main/resource/mapper/mysql/路径下创建MysqlStudentMapper.xml：

<?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.springboot.mysqldao.MysqlStudentMapper">  
    <select id="getAllStudents" resultType="java.util.Map">
        select * from student
    </select>
</mapper>

在src/main/resource/mapper/oracle/路径下创建OracleStudentMapper.xml：

<?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.springboot.oracledao.OracleStudentMapper">  
    <select id="getAllStudents" resultType="java.util.Map">
        select * from student
    </select>
</mapper>