mybatisplus 怎么配置多数据源

Mybatis-Plus 支持多数据源配置。可以使用 Spring Boot 的多数据源配置，也可以通过 Mybatis-Plus 提供的 `MybatisSqlSessionFactoryBean` 实现多数据源配置。

下面是使用 `MybatisSqlSessionFactoryBean` 实现多数据源配置的示例：

1. 创建数据源配置类

@Configuration
public class DataSourceConfig {
    
    @Bean("db1")
    @ConfigurationProperties(prefix = "spring.datasource.db1")
    public DataSource db1() {
        return DataSourceBuilder.create().build();
    }
    
    @Bean("db2")
    @ConfigurationProperties(prefix = "spring.datasource.db2")
    public DataSource db2() {
        return DataSourceBuilder.create().build();
    }
}

2. 创建 Mybatis Sql Session Factory Bean

@Configuration
public class MybatisConfig {
    
    @Bean
    @Primary
    public MybatisSqlSessionFactoryBean db1SqlSessionFactory(@Qualifier("db1") DataSource dataSource) {
        MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/db1/*.xml"));
        return sqlSessionFactoryBean;
    }
    
    @Bean
    public MybatisSqlSessionFactoryBean db2SqlSessionFactory(@Qualifier("db2") DataSource dataSource) {
        MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/db2/*.xml"));
        return sqlSessionFactoryBean;
    }
    
    @Bean
    public SqlSessionTemplate db1SqlSessionTemplate(@Qualifier("db1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
    
    @Bean
    public SqlSessionTemplate db2SqlSessionTemplate(@Qualifier("db2SqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

3. 配置多数据源事务管理器

@Configuration
@EnableTransactionManagement
public class TransactionConfig {
    
    @Bean
    public DataSourceTransactionManager db1TransactionManager(@Qualifier("db1") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
    
    @Bean
    public DataSourceTransactionManager db2TransactionManager(@Qualifier("db2") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

4. 配置数据源选择切换器

@Configuration
public class DataSourceSwitchConfig {
    
    @Bean
    @Primary
    public DataSource dataSource(@Qualifier("db1") DataSource db1, @Qualifier("db2") DataSource db2) {
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(DataSourceType.DB1.name(), db1);
        targetDataSources.put(DataSourceType.DB2.name(), db2);
        dynamicDataSource.setTargetDataSources(targetDataSources);
        dynamicDataSource.setDefaultTargetDataSource(db1);
        return dynamicDataSource;
    }
    
    @Bean
    public DataSourceContextHolder dataSourceContextHolder() {
        return new DataSourceContextHolder();
    }
    
    @Bean
    @Primary
    public DataSourceTransactionManager transactionManager(@Qualifier("dataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
    
    @Bean
    public AspectJExpressionPointcutAdvisor dataSourceSwitchAdvisor(@Qualifier("dataSource") DataSource dataSource) {
        AspectJExpressionPointcutAdvisor advisor = new AspectJExpressionPointcutAdvisor();
        advisor.setExpression("execution(public * com.example.demo.*.service.*.*(..))");
        advisor.setAdvice(new DataSourceSwitchAdvice(dataSource));
        return advisor;
    }
}

其中，`DynamicDataSource` 是继承自 `AbstractRoutingDataSource` 的动态数据源，`DataSourceType` 是枚举类型，用于定义数据源类型，`DataSourceContextHolder` 是用于存储当前数据源类型的上下文，`DataSourceSwitchAdvice` 是用于切换数据源的 AOP 切面。