SpringData3.0 新特性详解

// 使用密封类定义实体类型
public sealed interface Customer permits RegularCustomer, PremiumCustomer {
    String getId();
    String getName();
}
public record RegularCustomer(String id, String name, int points) implements Customer {}
public record PremiumCustomer(String id, String name, int tier, List<String> benefits) implements Customer {}

// 统一的反应式仓库接口
public interface ReactiveCrudRepository<T, ID> extends Repository<T, ID> {
    Mono<T> save(T entity);
    Mono<T> findById(ID id);
    Flux<T> findAll();
    Mono<Void> deleteById(ID id);
}

@Service
public class CustomerService {
    private final ReactiveCustomerRepository repository;
    
    @Autowired
    public CustomerService(ReactiveCustomerRepository repository) {
        this.repository = repository;
    }
    
    @Transactional
    public Mono<Customer> createCustomer(Customer customer) {
        return repository.save(customer)
            .doOnSuccess(savedCustomer -> {
                // 业务逻辑
            });
    }
}

@Configuration
public class AsyncConfig {
    @Bean
    public Executor taskExecutor() {
        return Executors.newVirtualThreadPerTaskExecutor();
    }
}

@Service
public class ProductService {
    private final ProductRepository repository;
    
    @Autowired
    public ProductService(ProductRepository repository) {
        this.repository = repository;
    }
    
    @Async
    public CompletableFuture<List<Product>> findProductsByCategory(String category) {
        return CompletableFuture.supplyAsync(() -> 
            repository.findByCategory(category)
        );
    }
}

public interface UserRepository extends JpaRepository<User, Long> {
    // 更简洁的方法命名
    List<User> findByEmailContainingIgnoreCase(String email);
    
    // 支持复杂条件
    List<User> findByAgeGreaterThanAndActiveTrue(int age);
    
    // 支持排序和分页
    Page<User> findByLastName(String lastName, Pageable pageable);
}

public interface OrderRepository extends JpaRepository<Order, Long> {
    // 支持更复杂的 JPQL 查询
    @Query("SELECT o FROM Order o WHERE o.customer.id = :customerId AND o.status = :status")
    List<Order> findByCustomerIdAndStatus(@Param("customerId") Long customerId, @Param("status") String status);
    
    // 支持原生 SQL 查询
    @Query(value = "SELECT * FROM orders WHERE total_amount > :amount", nativeQuery = true)
    List<Order> findOrdersWithAmountGreaterThan(@Param("amount") BigDecimal amount);
}

public interface ProductRepository extends JpaRepository<Product, Long> {
    // 批量保存
    <S extends Product> List<S> saveAll(Iterable<S> entities);
    
    // 批量删除
    void deleteAllInBatch(Iterable<Product> entities);
}

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    @Cacheable("users")
    Optional<User> findById(Long id);
    
    @CacheEvict(value = "users", key = "#user.id")
    <S extends User> S save(S user);
}

@Document(collection = "products")
public class Product {
    @Id
    private String id;
    private String name;
    private BigDecimal price;
    private List<String> tags;
    
    // 构造函数、getter 和 setter
}

public interface ProductRepository extends MongoRepository<Product, String> {
    List<Product> findByTagsContaining(String tag);
    
    @Aggregation(pipeline = {
        "{ '$match': { 'price': { '$gt': ?0 } } }",
        "{ '$group': { '_id': '$category', 'averagePrice': { '$avg': '$price' } } }"
    })
    List<CategoryAveragePrice> calculateAveragePriceByCategory(double minPrice);
}

@Repository
public interface UserRepository extends RedisRepository<User, String> {
    @RedisHash("users")
    List<User> findByLastName(String lastName);
    
    @TimeToLive
    long getTimeToLive();
}

@Configuration
@EnableJpaRepositories(basePackages = "com.example.repositories")
@EntityScan(basePackages = "com.example.entities")
public class JpaConfig {
    // 简化的配置
}

try {
    userRepository.save(user);
} catch (DataIntegrityViolationException e) {
    // 处理数据完整性 violation
} catch (OptimisticLockingFailureException e) {
    // 处理乐观锁失败
} catch (PersistenceException e) {
    // 处理其他持久化异常
}

// 推荐的代码组织结构
com.example
├── entities/          // 实体类
├── repositories/      // 仓库接口
├── services/          // 业务逻辑
└── controllers/       // 控制器