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在Spring Boot中，通过AbstractRoutingDataSource实现多数据源连接是一种常见的做法。这种技术允许你在运行时动态地切换数据源，从而支持对多个数据库的操作。Spring Boot中配置和使用AbstractRoutingDataSource来实现多数据源连接。

1. 添加依赖

pom.xml文件的依赖，比如Spring Data JPA和数据库驱动：

<dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><!-- 其他依赖 -->
</dependencies>

2. 配置数据源属性

在application.yml或application.properties中配置多个数据源的信息。例如：

spring:datasource:primary:url: jdbc:mysql://localhost:3306/primary_dbusername: rootpassword: rootdriver-class-name: com.mysql.cj.jdbc.Driversecondary:url: jdbc:mysql://localhost:3306/secondary_dbusername: rootpassword: rootdriver-class-name: com.mysql.cj.jdbc.Driver

3. 创建数据源配置类

创建两个数据源配置类，分别用于配置主数据源和次数据源。

@Configuration
public class DataSourceConfig {@Bean(name = "primaryDataSource")@ConfigurationProperties(prefix = "spring.datasource.primary")public DataSource primaryDataSource() {return DataSourceBuilder.create().build();}@Bean(name = "secondaryDataSource")@ConfigurationProperties(prefix = "spring.datasource.secondary")public DataSource secondaryDataSource() {return DataSourceBuilder.create().build();}
}

4. 创建自定义数据源路由类

扩展AbstractRoutingDataSource类，并根据上下文信息动态返回数据源。

public class DynamicRoutingDataSource extends AbstractRoutingDataSource {@Overrideprotected Object determineCurrentLookupKey() {return DataSourceContextHolder.getDataSourceType();}
}

5. 创建数据源上下文持有者

用于在运行时设置和获取当前的数据源类型。

public class DataSourceContextHolder {private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();public static void setDataSourceType(String dataSourceType) {contextHolder.set(dataSourceType);}public static String getDataSourceType() {return contextHolder.get();}public static void clearDataSourceType() {contextHolder.remove();}
}

6. 配置多数据源

将数据源配置到Spring上下文中，并指定默认的数据源。

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "com.example.repository",entityManagerFactoryRef = "entityManagerFactory",transactionManagerRef = "transactionManager"
)
public class DataSourceRoutingConfig {@Autowired@Qualifier("primaryDataSource")private DataSource primaryDataSource;@Autowired@Qualifier("secondaryDataSource")private DataSource secondaryDataSource;@Beanpublic DataSource dataSource() {DynamicRoutingDataSource routingDataSource = new DynamicRoutingDataSource();Map<Object, Object> targetDataSources = new HashMap<>();targetDataSources.put("primary", primaryDataSource);targetDataSources.put("secondary", secondaryDataSource);routingDataSource.setTargetDataSources(targetDataSources);routingDataSource.setDefaultTargetDataSource(primaryDataSource);return routingDataSource;}@Beanpublic LocalContainerEntityManagerFactoryBean entityManagerFactory(EntityManagerFactoryBuilder builder) {return builder.dataSource(dataSource()).packages("com.example.entity").persistenceUnit("multiple-pu").build();}@Beanpublic PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {return new JpaTransactionManager(entityManagerFactory);}
}

7. 使用AOP切换数据源

通过AOP在方法执行前设置数据源类型，并在方法执行后清除。

@Aspect
@Component
public class DataSourceAspect {@Before("@annotation(targetDataSource)")public void changeDataSource(JoinPoint point, TargetDataSource targetDataSource) throws Throwable {DataSourceContextHolder.setDataSourceType(targetDataSource.value());}@After("@annotation(targetDataSource)")public void clearDataSource(JoinPoint point, TargetDataSource targetDataSource) {DataSourceContextHolder.clearDataSourceType();}
}

自定义注解TargetDataSource：

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

8. 使用自定义注解切换数据源

在需要使用特定数据源的方法或类上使用@TargetDataSource注解。

@Service
public class UserService {@Autowiredprivate UserRepository userRepository;@TargetDataSource("primary")public User findUserById(Long id) {return userRepository.findById(id).orElse(null);}@TargetDataSource("secondary")public User findUserBySecondaryId(Long id) {// 假设secondary数据库有一个类似的表结构return userRepository.findById(id).orElse(null);}
}

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