<dependency>
    <groupId>org.apache.shardingsphere</groupId>
    <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
    <version>5.1.2</version> <!-- 選擇合適的版本 -->
</dependency>

spring:
  shardingsphere:
    datasource:
      names: master,slave0,slave1
      master:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        jdbc-url: jdbc:mysql://localhost:3306/master_db?serverTimezone=UTC&useSSL=false
        username: root
        password: root
      slave0:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        jdbc-url: jdbc:mysql://localhost:3306/slave0_db?serverTimezone=UTC&useSSL=false
        username: root
        password: root
      slave1:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        jdbc-url: jdbc:mysql://localhost:3306/slave1_db?serverTimezone=UTC&useSSL=false
        username: root
        password: root
 
    rules:
      replica-query:
        data-sources:
          pr_ds:
            primary-data-source-name: master
            replica-data-source-names:
              - slave0
              - slave1
            load-balancer-name: round_robin  # 負載均衡策略
        load-balancers:
          round_robin:
            type: ROUND_ROBIN  # 輪詢負載均衡策略

@Configuration
public class TransactionConfig {
 
    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

@Service
public class UserService {
 
    @Autowired
    private UserMapper userMapper;
 
    @Transactional
    public void createUser(User user) {
        userMapper.insert(user);  // 插入操作會走主庫
    }
 
    public User getUserById(Long id) {
        return userMapper.selectById(id);  // 查詢操作會走從庫
    }
}