How to configure multiple databases in MyBatis?

To configure multiple databases in MyBatis, you can follow these steps:

Create multiple data source configurations: For each database, you will need to create a data source configuration in the MyBatis configuration file. You can define a data source using the `` element, which includes database connection information such as URL, username, and password. Set a unique id for each data source so you can refer to them in subsequent steps.

   <!-- 数据库 1 的数据源配置 -->
   <dataSource id="dataSource1" type="com.example.DataSourceType">
       <!-- 数据库连接信息 -->
   </dataSource>
   
   <!-- 数据库 2 的数据源配置 -->
   <dataSource id="dataSource2" type="com.example.DataSourceType">
       <!-- 数据库连接信息 -->
   </dataSource>

Create multiple SqlSessionFactoryBeans: Create a SqlSessionFactoryBean for each data source, and inject the corresponding data source configuration into each SqlSessionFactoryBean separately.

   @Configuration
   public class MyBatisConfig {
   
       @Autowired
       @Qualifier("dataSource1")
       private DataSource dataSource1;
   
       @Autowired
       @Qualifier("dataSource2")
       private DataSource dataSource2;
   
       @Bean
       public SqlSessionFactoryBean sqlSessionFactoryBean1() throws IOException {
           SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
           sqlSessionFactoryBean.setDataSource(dataSource1);
           // 其他配置...
           return sqlSessionFactoryBean;
       }
   
       @Bean
       public SqlSessionFactoryBean sqlSessionFactoryBean2() throws IOException {
           SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
           sqlSessionFactoryBean.setDataSource(dataSource2);
           // 其他配置...
           return sqlSessionFactoryBean;
       }
   
       // 其他配置...
   }

3. Create multiple MapperScannerConfigurers: Create a MapperScannerConfigurer for each SqlSessionFactoryBean, and inject the corresponding SqlSessionFactoryBean into each MapperScannerConfigurer separately.

   @Configuration
   public class MyBatisConfig {
   
       // ...
   
       @Bean
       public MapperScannerConfigurer mapperScannerConfigurer1() {
           MapperScannerConfigurer scannerConfigurer = new MapperScannerConfigurer();
           scannerConfigurer.setBasePackage("com.example.mapper1");
           scannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactoryBean1");
           return scannerConfigurer;
       }
   
       @Bean
       public MapperScannerConfigurer mapperScannerConfigurer2() {
           MapperScannerConfigurer scannerConfigurer = new MapperScannerConfigurer();
           scannerConfigurer.setBasePackage("com.example.mapper2");
           scannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactoryBean2");
           return scannerConfigurer;
       }
   
       // ...
   }

Using different namespaces in MyBatis mapping files: When writing SQL mapping files, it is necessary to use different namespaces to distinguish different databases. This can be specified by adding `` or `` in the mapping file.

   <!-- 数据库 1 的映射文件 -->
   <mapper namespace="com.example.mapper1">
       <!-- SQL语句 -->
   </mapper>
   
   <!-- 数据库 2 的映射文件 -->
   <mapper namespace="com.example.mapper2">
       <!-- SQL语句 -->
   </mapper>

By following the steps above, you can configure multiple databases in MyBatis, and differentiate them using different data sources, SessionFactories, and namespaces.