Spring Boot多数据源配置实战：Druid+MyBatisPlus整合指南

1. 项目概述在微服务架构盛行的当下Spring Boot项目经常需要同时连接多个数据库实例。最近在重构一个老旧的会员系统时就遇到了需要同时操作MySQL用户库和TiDB交易库的场景。经过多次踩坑终于实现了基于DruidMyBatisPlus的稳定多数据源方案。这个方案最大的特点在于完全兼容Spring Boot自动配置特性支持Druid连接池的各项监控指标保留MyBatisPlus的所有便捷操作事务管理清晰可控特别提醒多数据源配置中最容易犯的错误就是混淆Mapper接口和XML文件的路径配置这会导致经典的Invalid bound statement异常。2. 核心配置解析2.1 依赖管理关键点在pom.xml中需要特别注意这些依赖项properties spring-boot.version2.7.12/spring-boot.version druid.version1.2.16/druid.version mybatis-plus.version3.5.3.1/mybatis-plus.version /properties dependencies !-- 核心starter -- dependency groupIdcom.alibaba/groupId artifactIddruid-spring-boot-starter/artifactId version${druid.version}/version /dependency !-- MyBatisPlus必须单独指定版本 -- dependency groupIdcom.baomidou/groupId artifactIdmybatis-plus-boot-starter/artifactId version${mybatis-plus.version}/version exclusions exclusion groupIdcom.zaxxer/groupId artifactIdHikariCP/artifactId /exclusion /exclusions /dependency /dependencies这里有个重要细节MyBatisPlus默认使用HikariCP需要通过exclusions强制移除否则会与Druid产生冲突。2.2 配置文件陷阱application.yml的配置需要特别注意格式spring: datasource: master: type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/master?useSSLfalse username: root password: 123456 druid: initial-size: 5 max-active: 20 validation-query: SELECT 1 slave: type: com.alibaba.druid.pool.DruidDataSource driver-class-name: com.mysql.cj.jdbc.Driver jdbc-url: jdbc:mysql://localhost:3306/slave?useSSLfalse username: root password: 123456 druid: initial-size: 3 max-active: 15致命陷阱第一个数据源用url属性后续数据源必须用jdbc-url否则启动时会报jdbcUrl is required错误。这是Spring Boot自动配置机制的特殊要求。3. 数据源配置实战3.1 主数据源配置Configuration MapperScan(basePackages com.example.mapper.master, sqlSessionFactoryRef masterSqlSessionFactory) public class MasterDataSourceConfig { Bean Primary ConfigurationProperties(spring.datasource.master) public DataSource masterDataSource() { return DruidDataSourceBuilder.create().build(); } Bean Primary public SqlSessionFactory masterSqlSessionFactory( Qualifier(masterDataSource) DataSource dataSource) throws Exception { MybatisSqlSessionFactoryBean sessionFactory new MybatisSqlSessionFactoryBean(); sessionFactory.setDataSource(dataSource); sessionFactory.setMapperLocations( new PathMatchingResourcePatternResolver() .getResources(classpath:mapper/master/*.xml)); // 关键注入MyBatisPlus配置 MybatisConfiguration configuration new MybatisConfiguration(); configuration.setMapUnderscoreToCamelCase(true); configuration.setDefaultScriptingLanguage(MybatisXMLLanguageDriver.class); sessionFactory.setConfiguration(configuration); sessionFactory.setPlugins(new MybatisPlusInterceptor()); return sessionFactory.getObject(); } // 其他必要bean... }3.2 从数据源配置Configuration MapperScan(basePackages com.example.mapper.slave, sqlSessionFactoryRef slaveSqlSessionFactory) public class SlaveDataSourceConfig { Bean ConfigurationProperties(spring.datasource.slave) public DataSource slaveDataSource() { return DruidDataSourceBuilder.create().build(); } Bean public SqlSessionFactory slaveSqlSessionFactory( Qualifier(slaveDataSource) DataSource dataSource) throws Exception { MybatisSqlSessionFactoryBean sessionFactory new MybatisSqlSessionFactoryBean(); sessionFactory.setDataSource(dataSource); sessionFactory.setMapperLocations( new PathMatchingResourcePatternResolver() .getResources(classpath:mapper/slave/*.xml)); // 复用主数据源的MyBatisPlus配置 MybatisConfiguration configuration new MybatisConfiguration(); configuration.setMapUnderscoreToCamelCase(true); sessionFactory.setConfiguration(configuration); sessionFactory.setPlugins(new MybatisPlusInterceptor()); return sessionFactory.getObject(); } // 其他必要bean... }4. 事务管理方案4.1 单数据源事务直接在Service方法上使用Transactional即可Service RequiredArgsConstructor public class OrderService { private final OrderMapper orderMapper; // 主库Mapper Transactional public void createOrder(Order order) { orderMapper.insert(order); } }4.2 跨数据源事务需要引入JTA实现如AtomikosBean public JtaTransactionManager transactionManager() { return new JtaTransactionManager(); } // 使用时指定事务管理器 Transactional(transactionManager transactionManager) public void crossDatabaseOperation() { masterMapper.insert(...); slaveMapper.update(...); }性能警告分布式事务会显著降低系统吞吐量建议通过最终一致性方案替代。5. 监控配置技巧Druid的监控面板配置Bean public ServletRegistrationBeanStatViewServlet druidServlet() { ServletRegistrationBeanStatViewServlet reg new ServletRegistrationBean(); reg.setServlet(new StatViewServlet()); reg.addUrlMappings(/druid/*); reg.addInitParameter(loginUsername, admin); reg.addInitParameter(loginPassword, admin); return reg; } Bean public FilterRegistrationBeanWebStatFilter filterRegistrationBean() { FilterRegistrationBeanWebStatFilter reg new FilterRegistrationBean(); reg.setFilter(new WebStatFilter()); reg.addUrlPatterns(/*); reg.addInitParameter(exclusions, *.js,*.gif,*.jpg,*.css,/druid/*); return reg; }访问http://localhost:8080/druid即可查看SQL监控、URI监控等数据。6. 常见问题排查6.1 Mapper绑定失败错误现象BindingException: Invalid bound statement (not found)解决方案检查MapperScan的basePackages是否包含对应Mapper接口检查setMapperLocations路径是否包含XML文件确认XML中的namespace与Mapper接口全限定名一致6.2 事务不生效可能原因方法不是public自调用this.method()异常被catch未抛出数据库引擎不支持事务如MyISAM6.3 连接泄漏Druid监控面板查看activeCount持续增长检查代码中是否忘记关闭Connection/Statement/ResultSet7. 性能优化建议连接池参数调优druid: min-idle: 5 max-active: 50 max-wait: 3000 time-between-eviction-runs-millis: 60000 min-evictable-idle-time-millis: 300000MyBatisPlus二级缓存Bean public MybatisPlusInterceptor mybatisPlusInterceptor() { MybatisPlusInterceptor interceptor new MybatisPlusInterceptor(); interceptor.addInnerInterceptor(new PaginationInnerInterceptor()); interceptor.addInnerInterceptor(new CachingInnerInterceptor()); return interceptor; }SQL监控慢查询阈值druid: filter: stat: log-slow-sql: true slow-sql-millis: 10008. 扩展思考对于更复杂的多租户场景可以考虑动态数据源路由AbstractRoutingDataSourceSchema级别隔离MyBatisPlus租户插件在K8s环境中部署时建议使用ConfigMap管理数据源配置为每个Pod设置合理的连接池大小实现健康检查接口监控连接状态