🔧Cấu Hình Spring Boot Kết Nối Hai Database PostgreSQL

📌 1. Cấu hình application.yml

Thêm thông tin kết nối cho 2 database vào application.yml:

spring:
  datasource:
    primary:
      url: jdbc:postgresql://localhost:5432/db_primary
      username: user_primary
      password: pass_primary
      driver-class-name: org.postgresql.Driver
    secondary:
      url: jdbc:postgresql://localhost:5432/db_secondary
      username: user_secondary
      password: pass_secondary
      driver-class-name: org.postgresql.Driver
  jpa:
    properties:
      hibernate:
        dialect: org.hibernate.dialect.PostgreSQLDialect
    hibernate:
      ddl-auto: update

---

🏗 2. Cấu hình Primary Database

📌 Tạo file PrimaryDatabaseConfig.java:

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
    basePackages = "com.example.repository.primary",
    entityManagerFactoryRef = "primaryEntityManagerFactory",
    transactionManagerRef = "primaryTransactionManager"
)
public class PrimaryDatabaseConfig {

    @Primary
    @Bean(name = "primaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    public DataSource dataSource() {
        return DataSourceBuilder.create().build();
    }

    @Primary
    @Bean(name = "primaryEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            EntityManagerFactoryBuilder builder, @Qualifier("primaryDataSource") DataSource dataSource) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.model.primary")
                .persistenceUnit("primary")
                .build();
    }

    @Primary
    @Bean(name = "primaryTransactionManager")
    public PlatformTransactionManager transactionManager(
            @Qualifier("primaryEntityManagerFactory") EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}

---

🏗 3. Cấu hình Secondary Database

📌 Tạo file SecondaryDatabaseConfig.java:

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
    basePackages = "com.example.repository.secondary",
    entityManagerFactoryRef = "secondaryEntityManagerFactory",
    transactionManagerRef = "secondaryTransactionManager"
)
public class SecondaryDatabaseConfig {

    @Bean(name = "secondaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.secondary")
    public DataSource dataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "secondaryEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            EntityManagerFactoryBuilder builder, @Qualifier("secondaryDataSource") DataSource dataSource) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.model.secondary")
                .persistenceUnit("secondary")
                .build();
    }

    @Bean(name = "secondaryTransactionManager")
    public PlatformTransactionManager transactionManager(
            @Qualifier("secondaryEntityManagerFactory") EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}

---

📂 4. Tạo Entity & Repository cho từng database

🏛 Primary Database

Entity:

@Entity
@Table(name = "users")
public class PrimaryUser {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
}

Repository:

@Repository
public interface PrimaryUserRepository extends JpaRepository<PrimaryUser, Long> {
}

🏛 Secondary Database

Entity:

@Entity
@Table(name = "customers")
public class SecondaryUser {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String email;
}

Repository:

@Repository
public interface SecondaryUserRepository extends JpaRepository<SecondaryUser, Long> {
}

---

⚙️ 5. Sử dụng Service để thao tác với 2 database

@Service
public class UserService {
    private final PrimaryUserRepository primaryUserRepository;
    private final SecondaryUserRepository secondaryUserRepository;

    @Autowired
    public UserService(PrimaryUserRepository primaryUserRepository, SecondaryUserRepository secondaryUserRepository) {
        this.primaryUserRepository = primaryUserRepository;
        this.secondaryUserRepository = secondaryUserRepository;
    }

    @Transactional("primaryTransactionManager")
    public void saveToPrimaryDB(PrimaryUser user) {
        primaryUserRepository.save(user);
    }

    @Transactional("secondaryTransactionManager")
    public void saveToSecondaryDB(SecondaryUser user) {
        secondaryUserRepository.save(user);
    }
}

---

📌 6. Kết luận

✅ Bước	🎯 Hành động
1	Cấu hình 2 DataSource trong application.yml
2	Tạo PrimaryDatabaseConfig để cấu hình database chính
3	Tạo SecondaryDatabaseConfig để cấu hình database phụ
4	Tạo Entity & Repository riêng cho mỗi database
5	Sử dụng @Transactional để thao tác đúng database

🚀 Sau khi hoàn thành, Spring Boot sẽ kết nối & thao tác được với cả 2 database PostgreSQL!