业务系统复杂程度增加，为了解决数据库I/O瓶颈，很自然会进行拆库拆表分服务来应对。这就会出现一个系统中可能会访问多处数据库，需要配置多个数据源。

第一种场景：项目服务从其它多处数据库取基础数据进行业务处理，因此各库之间不会出现重表等情况。

第二种场景：为了减轻写入压力进行读写分库，读走从库，写为主库。此种表名等信息皆为一致。

第三种场景：以上两种皆有。对于某些业务需要大数据量的汇总统计，希望不影响正常业务必须走从库（表信息一致），某些配置信息不存在读写压力，出现不分库（表信息不一致）

项目源代码：

https://github.com/zzsong/springboot-multiple-datasource.git

有三个目录：

one:
直接使用多@Bean配置，@MapperScan来路径区分读何库

two:
使用注解的方式来标识走何dataSource,AOP拦截注入动态数据源

third:
使用spring的Bean命名策略进行区分数据来源

项目技术选型： springBoot2.2.5 + mybatis + druid + mysql

先看主要的pom包

<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.2.5.RELEASE</version> <relativePath/> </parent> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jdbc</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jdbc</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.1.2</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.19</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.21</version> </dependency>

application.yml

spring: datasource: druid: core: url: jdbc:mysql:///kc_core?characterEncoding=utf-8&serverTimezone=Asia/Shanghai username: root password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver type: com.alibaba.druid.pool.DruidDataSource schedule: url: jdbc:mysql:///kc_schedule?characterEncoding=utf-8&serverTimezone=Asia/Shanghai username: root password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver type: com.alibaba.druid.pool.DruidDataSource

mysql新版本必须带有serverTimezone，不然会报连接异常。

第一种：通过@MapperScans 扫描匹配相关的数据源

@Configuration@MapperScans({ @MapperScan(basePackages = "com.zss.one.mapper.core", sqlSessionTemplateRef = "coreSqlSessionTemplate",sqlSessionFactoryRef = "coreSqlSessionFactory"), @MapperScan(basePackages = "com.zss.one.mapper.schedule", sqlSessionTemplateRef = "scheduleSqlSessionTemplate",sqlSessionFactoryRef = "scheduleSqlSessionFactory")})public class MybatisOneConfig { @Bean @ConfigurationProperties(prefix = "spring.datasource.druid.core") public DataSource coreDataSource(){ return DruidDataSourceBuilder.create().build(); } @Bean public SqlSessionFactory coreSqlSessionFactory(@Qualifier("coreDataSource") DataSource coreDataSource) throws Exception { SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean(); sessionFactory.setDataSource(coreDataSource); sessionFactory.getObject().getConfiguration().setJdbcTypeForNull(null); sessionFactory.getObject().getConfiguration().setMapUnderscoreToCamelCase(true); return sessionFactory.getObject(); } @Bean public SqlSessionTemplate coreSqlSessionTemplate(@Qualifier("coreSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception { return new SqlSessionTemplate(sqlSessionFactory); } //======schedule======== @Bean @ConfigurationProperties(prefix = "spring.datasource.druid.schedule") public DataSource scheduleDataSource(){ return DruidDataSourceBuilder.create().build(); } @Bean public SqlSessionFactory scheduleSqlSessionFactory(@Qualifier("scheduleDataSource") DataSource coreDataSource) throws Exception { SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean(); sessionFactory.setDataSource(coreDataSource); sessionFactory.getObject().getConfiguration().setJdbcTypeForNull(null); sessionFactory.getObject().getConfiguration().setMapUnderscoreToCamelCase(true); return sessionFactory.getObject(); } @Bean public SqlSessionTemplate scheduleSqlSessionTemplate(@Qualifier("scheduleSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception { return new SqlSessionTemplate(sqlSessionFactory); }}

第二种是动态数据源模式，通过AOP切入注解引导使用何数据源。用自定义注解@interface来标识方法走对应的数据源。

注意事项：类中的方法再调用带数据源的方法，不能被AOP切入

@Target({ElementType.METHOD, ElementType.TYPE})@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface TargetDataSource { String value();}

extends spring的动态DataSource路由来匹配

public class DynamicDataSource extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return DataSourceContextRouting.getDataSourceName(); }}@Configuration//@EnableConfigurationProperties(MybatisProperties.class)//不要使用此公共配置，Configuration会破坏相关dataSource的配置@MapperScan("com.zss.two.mapper")public class MybatisConfig { @Bean @ConfigurationProperties(prefix = "spring.datasource.druid.core") public DataSource coreDataSource() { return DruidDataSourceBuilder.create().build(); } @Bean @ConfigurationProperties(prefix = "spring.datasource.druid.schedule") public DataSource scheduleDataSource() { return DruidDataSourceBuilder.create().build(); } @Autowired @Qualifier("coreDataSource") private DataSource coreDataSource; @Autowired @Qualifier("scheduleDataSource") private DataSource scheduleDataSource; @Bean public DynamicDataSource dataSource() { Map<Object, Object> targetDataSources = new HashMap<>(); targetDataSources.put(DataSourceConstants.CORE_DATA_SOURCE, coreDataSource); targetDataSources.put(DataSourceConstants.SCHEDULE_DATA_SOURCE, scheduleDataSource); DynamicDataSource dataSource = new DynamicDataSource(); //设置数据源映射 dataSource.setTargetDataSources(targetDataSources);//// 设置默认数据源，当无法映射到数据源时会使用默认数据源 dataSource.setDefaultTargetDataSource(coreDataSource); dataSource.afterPropertiesSet(); return dataSource; } /** * 根据数据源创建SqlSessionFactory */ @Bean public SqlSessionFactory sqlSessionFactory(DynamicDataSource dataSource) throws Exception { SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean(); sessionFactory.setDataSource(dataSource); sessionFactory.getObject().getConfiguration().setJdbcTypeForNull(null); sessionFactory.getObject().getConfiguration().setMapUnderscoreToCamelCase(true); return sessionFactory.getObject(); } @Bean public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) throws Exception { return new SqlSessionTemplate(sqlSessionFactory); }

第三种，自定义Bean命名策略，按beanName进行自动匹配使用数据源

@Componentpublic class CoreBeanNameGenerator implements BeanNameGenerator { @Override public String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) { return "core"+ ClassUtils.getShortName(definition.getBeanClassName()); }}@Componentpublic class ScheduleBeanNameGenerator implements BeanNameGenerator { @Override public String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) { return "schedule"+ ClassUtils.getShortName(definition.getBeanClassName()); }}

使用mybatis MapperScannerConfigurer自动扫描，将Mapper接口生成注入到spring

@Bean public MapperScannerConfigurer coreMapperScannerConfig(CoreBeanNameGenerator coreBeanNameGenerator){ MapperScannerConfigurer configurer = new MapperScannerConfigurer(); configurer.setNameGenerator(coreBeanNameGenerator); configurer.setBasePackage("com.zss.third.mapper.core,com.zss.third.mapper.order"); configurer.setSqlSessionFactoryBeanName("coreSqlSessionFactory"); configurer.setSqlSessionTemplateBeanName("coreSqlSessionTemplate"); return configurer; } @Bean public MapperScannerConfigurer scheduleMapperScannerConfig(ScheduleBeanNameGenerator scheduleBeanNameGenerator){ MapperScannerConfigurer configurer = new MapperScannerConfigurer(); configurer.setNameGenerator(scheduleBeanNameGenerator); configurer.setBasePackage("com.zss.third.mapper.schedule,com.zss.third.mapper.order"); configurer.setSqlSessionFactoryBeanName("scheduleSqlSessionFactory"); configurer.setSqlSessionTemplateBeanName("scheduleSqlSessionTemplate"); return configurer; }

到此，三种多数据源匹配主要点介绍完，详细直接下载github项目。 在resources/db含有相关测试表及数据脚本。

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