projeto\r\n \u251c\u2500 application\r\n \u2502 \u2514\u2500 dto\r\n \u2502\r\n \u251c\u2500 domain\r\n \u2502 \u2514\u2500 model\r\n \u2502\r\n \u2514\u2500 infrastructure\r\n \u2514\u2500 entity<\/code><\/pre>\n<\/div>\nApplication<\/h3>\n
Respons\u00e1vel pela entrada e sa\u00edda de dados<\/strong> da aplica\u00e7\u00e3o.<\/p>\nExemplos:<\/p>\n
\n- \n
APIs REST<\/p>\n<\/li>\n
- \n
Mensageria<\/p>\n<\/li>\n
- \n
integra\u00e7\u00e3o com outros servi\u00e7os<\/p>\n<\/li>\n<\/ul>\n
Utiliza DTOs<\/strong>.<\/p>\nDomain<\/h3>\n
Aqui vivem as regras de neg\u00f3cio<\/strong>.<\/p>\nEssa camada deve ser independente de frameworks<\/strong>.<\/p>\nUtiliza Model<\/strong>.<\/p>\nInfrastructure<\/h3>\n
Respons\u00e1vel pela comunica\u00e7\u00e3o com recursos externos:<\/p>\n
\n- \n
banco de dados<\/p>\n<\/li>\n
- \n
APIs externas<\/p>\n<\/li>\n
- \n
mensageria<\/p>\n<\/li>\n
- \n
cache<\/p>\n<\/li>\n<\/ul>\n
Utiliza Entities<\/strong>.<\/p>\nFluxo de dados no DDD com DTO, Model e Entity<\/h2>\n
O fluxo t\u00edpico de dados pode ser representado assim:<\/p>\n
![\"\"](\"http:\/\/www.isacaguiar.com.br\/blog\/wp-content\/uploads\/2026\/03\/mermaid-diagram-1.png\")
<\/p>\n
<\/p>\n
Os objetos s\u00e3o convertidos entre si utilizando mappers<\/strong>.<\/p>\n
\nModelando o dom\u00ednio do sistema<\/h2>\n
Nosso exemplo ter\u00e1 tr\u00eas objetos principais.<\/p>\n
![\"\"](\"http:\/\/www.isacaguiar.com.br\/blog\/wp-content\/uploads\/2026\/03\/mermaid-diagram-2.png\")
<\/p>\n
DTOs (Application Layer)<\/h2>\n
DTOs representam os dados de entrada e sa\u00edda da aplica\u00e7\u00e3o<\/strong>.<\/p>\n\n
public record ClientDTO(Long id, String name, String documentNumber) {\r\n}<\/code><\/pre>\n<\/div>\n\n
public record AccountDTO(Long id, ClientDTO client, List items) {\r\n public AccountDTO {\r\n items = items == null ? List.of() : List.copyOf(items);\r\n }\r\n}<\/itembuydto><\/code><\/pre>\n<\/div>\n\n
public record ItemBuyDTO(Long id, String description, BigDecimal value) {\r\n}<\/code><\/pre>\n<\/div>\nDTOs devem ser simples e sem regras de neg\u00f3cio<\/strong>.<\/p>\nModels (Domain Layer)<\/h2>\n
Representa o modelo de dom\u00ednio da aplica\u00e7\u00e3o<\/strong>.<\/p>\nEles costumam ser imut\u00e1veis<\/strong>.<\/p>\n\n
public record Client(Long id, String name, String docNumber) {\r\n}<\/code><\/pre>\n<\/div>\n\n
public record Account(Long id, Client client, List items) {\r\n}<\/itembuy><\/code><\/pre>\n<\/div>\n\n
public record ItemBuy(Long id, String description, BigDecimal value) {\r\n}<\/code><\/pre>\n<\/div>\nEntities (Infrastructure Layer)<\/h2>\n
Entities representam dados persistidos no banco<\/strong>.<\/p>\n\n
@Getter\r\n@Setter\r\n@Entity\r\n@NoArgsConstructor\r\npublic class ClientEntity {\r\n\r\n @Id\r\n @GeneratedValue(strategy = GenerationType.SEQUENCE)\r\n @Column(nullable = false)\r\n private Long id;\r\n\r\n private String name;\r\n\r\n private String docNumber;\r\n\r\n}<\/code><\/pre>\n<\/div>\n\n
@Getter\r\n@Setter\r\n@Entity\r\npublic class AccountEntity {\r\n\r\n @Id\r\n @GeneratedValue(strategy = GenerationType.SEQUENCE)\r\n @Column(nullable = false)\r\n private Long id;\r\n\r\n @ManyToOne\r\n private ClientEntity client;\r\n\r\n private List items;\r\n\r\n}<\/itembuyentity><\/code><\/pre>\n<\/div>\n\n
@Getter\r\n@Setter\r\n@Entity\r\npublic class ItemBuyEntity {\r\n @Id\r\n @GeneratedValue(strategy = GenerationType.SEQUENCE)\r\n @Column(nullable = false)\r\n private Long id;\r\n\r\n private String description;\r\n private BigDecimal value;\r\n}<\/code><\/pre>\n<\/div>\nMapStruct no DDD com Java e Spring<\/h2>\n
Para converter objetos entre camadas, podemos utilizar MapStruct<\/strong>, que gera c\u00f3digo automaticamente.<\/p>\nExemplo:<\/p>\n
\n
@Mapper(componentModel = \"spring\")\r\npublic interface ClientMapper {\r\n\r\n @Mapping(target = \"docNumber\", source = \"documentNumber\")\r\n Client dtoToModel(ClientDTO dto);\r\n\r\n ClientEntity modelToEntity(Client vo);\r\n\r\n @Mapping(target = \"documentNumber\", source = \"docNumber\")\r\n ClientDTO modelToDto(Client vo);\r\n\r\n Client entityToModel(ClientEntity entity);\r\n\r\n}<\/code><\/pre>\n<\/div>\nA anota\u00e7\u00e3o:<\/p>\n
\n
@Mapping(target = \"docNumber\", source = \"documentNumber\")<\/code><\/pre>\n<\/div>\nindica que:<\/p>\n
\n
DTO.documentNumber -> Model.docNumber<\/code><\/pre>\n<\/div>\nQuando os nomes dos atributos s\u00e3o iguais, n\u00e3o precisamos utilizar @Mapping<\/code>.<\/p>\nExemplo:<\/p>\n
\n
nome -> nome<\/code><\/pre>\n<\/div>\nMapStruct faz esse mapeamento automaticamente.<\/p>\n
Testando o Mapper<\/h2>\n
Podemos validar o comportamento com testes unit\u00e1rios.<\/p>\n
\n
@SpringJUnitConfig(classes = {\r\n ClientMapperImpl.class\r\n})\r\nclass ClientMapperTest {\r\n\r\n @Autowired\r\n private ClientMapper mapper;\r\n\r\n @Test\r\n void shouldConvertDtoToModel() {\r\n ClientDTO dto = new ClientDTO(null, \"Maria\", \"12345678900\");\r\n\r\n Client model = mapper.dtoToModel(dto);\r\n\r\n assertAll(\r\n () -> assertNull(model.id()),\r\n () -> assertEquals(\"Maria\", model.name()),\r\n () -> assertEquals(\"12345678900\", model.docNumber())\r\n );\r\n }\r\n\r\n @Test\r\n void shouldConvertModelToEntity() {\r\n Client model = new Client(null, \"Maria\", \"12345678900\");\r\n\r\n ClientEntity entity = mapper.modelToEntity(model);\r\n\r\n assertAll(\r\n () -> assertNull(entity.getId()),\r\n () -> assertEquals(\"Maria\", entity.getName()),\r\n () -> assertEquals(\"12345678900\", entity.getDocNumber())\r\n );\r\n }\r\n\r\n @Test\r\n void shouldConvertModelToDto() {\r\n Client model = new Client(null, \"Maria\", \"12345678900\");\r\n\r\n ClientDTO dto = mapper.modelToDto(model);\r\n\r\n assertAll(\r\n () -> assertNull(dto.id()),\r\n () -> assertEquals(\"Maria\", dto.name()),\r\n () -> assertEquals(\"12345678900\", dto.documentNumber())\r\n );\r\n }\r\n\r\n @Test\r\n void shouldConvertEntityToModel() {\r\n ClientEntity entity = new ClientEntity();\r\n entity.setName(\"Maria\");\r\n entity.setDocNumber(\"12345678900\");\r\n\r\n Client model = mapper.entityToModel(entity);\r\n\r\n assertAll(\r\n () -> assertNull(model.id()),\r\n () -> assertEquals(\"Maria\", model.name()),\r\n () -> assertEquals(\"12345678900\", model.docNumber())\r\n );\r\n }\r\n\r\n @Test\r\n void shouldReturnNullWhenDtoIsNull() {\r\n assertNull(mapper.dtoToModel(null));\r\n }\r\n\r\n @Test\r\n void shouldReturnNullWhenModelIsNull() {\r\n assertNull(mapper.modelToEntity(null));\r\n assertNull(mapper.modelToDto(null));\r\n }\r\n\r\n @Test\r\n void shouldReturnNullWhenEntityIsNull() {\r\n assertNull(mapper.entityToModel(null));\r\n }\r\n}<\/code><\/pre>\n<\/div>\n\n
@SpringJUnitConfig(classes = {\r\n AccountMapperImpl.class,\r\n ClientMapperImpl.class\r\n})\r\nclass AccountMapperTest {\r\n\r\n @Autowired\r\n private AccountMapper mapper;\r\n\r\n @Test\r\n void shouldConvertDtoToModel() {\r\n ClientDTO clientDTO = new ClientDTO(1L, \"Maria\", \"12345678900\");\r\n ItemBuyDTO itemBuyDTO_1 = new ItemBuyDTO(1L, \"Produto Alfa\", new BigDecimal(\"10.00\"));\r\n ItemBuyDTO itemBuyDTO_2 = new ItemBuyDTO(2L, \"Produto Bravo\", new BigDecimal(\"20.00\"));\r\n AccountDTO accountDTO = new AccountDTO(1L, clientDTO, List.of(itemBuyDTO_1, itemBuyDTO_2));\r\n\r\n Account model = mapper.dtoToModel(accountDTO);\r\n\r\n assertAll(\r\n () -> assertEquals(1L, model.id()),\r\n () -> assertEquals(\"Maria\", model.client().name()),\r\n () -> assertEquals(\"12345678900\", model.client().docNumber()),\r\n () -> assertEquals(\"Produto Alfa\", model.items().get(0).description())\r\n );\r\n }\r\n\r\n @Test\r\n void shouldConvertModelToEntity() {\r\n Client client = new Client(1L, \"Maria\", \"12345678900\");\r\n ItemBuy itemBuy_1 = new ItemBuy(1L, \"Produto Alfa\", new BigDecimal(\"10.00\"));\r\n ItemBuy itemBuy_2 = new ItemBuy(2L, \"Produto Bravo\", new BigDecimal(\"20.00\"));\r\n Account account = new Account(null, client, List.of(itemBuy_1, itemBuy_2));\r\n\r\n AccountEntity entity = mapper.modelToEntity(account);\r\n\r\n assertAll(\r\n () -> assertNull(entity.getId()),\r\n () -> assertEquals(2, entity.getItems().size())\r\n );\r\n }\r\n\r\n @Test\r\n void shouldConvertModelToDto() {\r\n Client client = new Client(1L, \"Maria\", \"12345678900\");\r\n ItemBuy itemBuy_1 = new ItemBuy(1L, \"Produto Alfa\", new BigDecimal(\"10.00\"));\r\n ItemBuy itemBuy_2 = new ItemBuy(2L, \"Produto Bravo\", new BigDecimal(\"20.00\"));\r\n Account account = new Account(null, client, List.of(itemBuy_1, itemBuy_2));\r\n\r\n AccountDTO dto = mapper.modelToDto(account);\r\n\r\n assertAll(\r\n () -> assertNull(dto.id()),\r\n () -> assertEquals(\"Maria\", dto.client().name()),\r\n () -> assertEquals(\"12345678900\", dto.client().documentNumber()),\r\n () -> assertEquals(2, dto.items().size())\r\n\r\n );\r\n }\r\n\r\n @Test\r\n void shouldConvertEntityToModel() {\r\n ClientEntity clientEntity = new ClientEntity();\r\n clientEntity.setId(1L);\r\n clientEntity.setName(\"Maria\");\r\n clientEntity.setDocNumber(\"12345678900\");\r\n\r\n ItemBuyEntity itemBuy_1 = new ItemBuyEntity();\r\n itemBuy_1.setId(1L);\r\n itemBuy_1.setDescription(\"Produto Alfa\");\r\n itemBuy_1.setValue(new BigDecimal(\"10.00\"));\r\n ItemBuyEntity itemBuy_2 = new ItemBuyEntity();\r\n itemBuy_2.setId(2L);\r\n itemBuy_2.setDescription(\"Produto Bravo\");\r\n itemBuy_2.setValue(new BigDecimal(\"20.00\"));\r\n\r\n AccountEntity entity = new AccountEntity();\r\n entity.setId(1L);\r\n entity.setClient(clientEntity);\r\n entity.setItems(List.of(itemBuy_1, itemBuy_2));\r\n\r\n Account model = mapper.entityToModel(entity);\r\n\r\n assertAll(\r\n () -> assertEquals(1L, model.id()),\r\n () -> assertEquals(\"Maria\", model.client().name()),\r\n () -> assertEquals(\"12345678900\", model.client().docNumber()),\r\n () -> assertEquals(2, model.items().size())\r\n );\r\n }\r\n\r\n @Test\r\n void shouldReturnNullWhenDtoIsNull() {\r\n assertNull(mapper.dtoToModel(null));\r\n }\r\n\r\n @Test\r\n void shouldReturnNullWhenModelIsNull() {\r\n assertNull(mapper.modelToEntity(null));\r\n assertNull(mapper.modelToDto(null));\r\n }\r\n\r\n @Test\r\n void shouldReturnNullWhenEntityIsNull() {\r\n assertNull(mapper.entityToModel(null));\r\n }\r\n\r\n\r\n}<\/code><\/pre>\n<\/div>\nMapStruct vs ModelMapper<\/h2>\n
Uma d\u00favida comum \u00e9 qual biblioteca utilizar para mapeamento.<\/p>\n
\n
\n
\n\n\n| Caracter\u00edstica<\/th>\n | MapStruct<\/th>\n | ModelMapper<\/th>\n<\/tr>\n<\/thead>\n |
\n\n| Gera\u00e7\u00e3o de c\u00f3digo<\/td>\n | Compile time<\/td>\n | Runtime<\/td>\n<\/tr>\n |
\n| Performance<\/td>\n | Muito alta<\/td>\n | M\u00e9dia<\/td>\n<\/tr>\n |
\n| Seguran\u00e7a de tipos<\/td>\n | Alta<\/td>\n | M\u00e9dia<\/td>\n<\/tr>\n |
\n| Uso em projetos enterprise<\/td>\n | Muito comum<\/td>\n | Menos comum<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n Por gerar c\u00f3digo em tempo de compila\u00e7\u00e3o<\/strong>, MapStruct costuma ser a escolha preferida em sistemas Spring Boot de alta escala<\/strong>.<\/p>\nErros comuns ao usar DTO e Entity<\/h2>\nAlguns erros muito comuns em projetos Java:<\/p>\n |