業(yè)務系統(tǒng)復雜程度增加，為了解決數(shù)據(jù)庫I/O瓶頸，很自然會進行拆庫拆表分服務來應對。這就會出現(xiàn)一個系統(tǒng)中可能會訪問多處數(shù)據(jù)庫，需要配置多個數(shù)據(jù)源。

第一種場景：項目服務從其它多處數(shù)據(jù)庫取基礎數(shù)據(jù)進行業(yè)務處理，因此各庫之間不會出現(xiàn)重表等情況。

第二種場景：為了減輕寫入壓力進行讀寫分庫，讀走從庫，寫為主庫。此種表名等信息皆為一致。

第三種場景：以上兩種皆有。對于某些業(yè)務需要大數(shù)據(jù)量的匯總統(tǒng)計，希望不影響正常業(yè)務必須走從庫（表信息一致），某些配置信息不存在讀寫壓力，出現(xiàn)不分庫（表信息不一致）

項目源代碼：

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

有三個目錄：

one: 直接使用多@Bean配置，@MapperScan來路徑區(qū)分讀何庫

two: 使用注解的方式來標識走何dataSource,AOP攔截注入動態(tài)數(shù)據(jù)源

third: 使用spring的Bean命名策略進行區(qū)分數(shù)據(jù)來源

項目技術選型： 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新版本必須帶有serverTimezone，不然會報連接異常。

第一種：通過@MapperScans 掃描匹配相關的數(shù)據(jù)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); }}

第二種是動態(tài)數(shù)據(jù)源模式，通過AOP切入注解引導使用何數(shù)據(jù)源。用自定義注解@interface來標識方法走對應的數(shù)據(jù)源。

注意事項：類中的方法再調(diào)用帶數(shù)據(jù)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的動態(tài)DataSource路由來匹配

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會破壞相關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(); //設置數(shù)據(jù)源映射 dataSource.setTargetDataSources(targetDataSources);//// 設置默認數(shù)據(jù)源，當無法映射到數(shù)據(jù)源時會使用默認數(shù)據(jù)源 dataSource.setDefaultTargetDataSource(coreDataSource); dataSource.afterPropertiesSet(); return dataSource; } /** * 根據(jù)數(shù)據(jù)源創(chuàng)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); }

第三種，自定義Bean命名策略，按beanName進行自動匹配使用數(shù)據(jù)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自動掃描，將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，三種多數(shù)據(jù)源匹配主要點介紹完，詳細直接下載github項目。 在resources/db含有相關測試表及數(shù)據(jù)腳本。

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