SpringBoot中实现多数据源连接和切换的方案

<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>

spring:
  datasource:
    primary:
      url: jdbc:mysql://localhost:3306/primary_db
      username: root
      password: root
      driver-class-name: com.mysql.cj.jdbc.Driver
    secondary:
      url: jdbc:mysql://localhost:3306/secondary_db
      username: root
      password: root
      driver-class-name: com.mysql.cj.jdbc.Driver

@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();
    }
}

public class DynamicRoutingDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataSourceType();
    }
}

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();
    }
}

@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;

    @Bean
    public 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;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(dataSource())
                .packages("com.example.entity")
                .persistenceUnit("multiple-pu")
                .build();
    }

    @Bean
    public PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}

@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();
    }
}

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

@Service
public class UserService {

    @Autowired
    private 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);
    }
}