\uc548\ub155\ud558\uc138\uc694! \uc774\ubc88 \uae00\uc5d0\uc11c\ub294 \uc2a4\ud504\ub9c1 \ubd80\ud2b8\ub97c \uc774\uc6a9\ud55c \ubc31\uc5d4\ub4dc \uac1c\ubc1c \uacfc\uc815\uc5d0\uc11c \ud575\uc2ec\uc801\uc778 \uc5ed\ud560\uc744 \ub2f4\ub2f9\ud558\ub294 \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\uc5d0 \ub300\ud574 \uc0c1\uc138\ud558\uac8c \uc54c\uc544\ubcf4\uaca0\uc2b5\ub2c8\ub2e4. JPA\ub294 \uc790\ubc14 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc640\uc758 \uc0c1\ud638\uc791\uc6a9\uc744 \ud6a8\uc728\uc801\uc73c\ub85c \ucc98\ub9ac\ud560 \uc218 \uc788\uac8c \ud574\uc8fc\ub294 ORM(Object-Relational Mapping) \uae30\uc220\uc785\ub2c8\ub2e4.<\/p>\n<\/header>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub294 \uc2a4\ud504\ub9c1 \ud504\ub808\uc784\uc6cc\ud06c\uc640 JPA(Java Persistence API)\ub97c \ud1b5\ud569\ud558\uc5ec \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 CRUD(Create, Read, Update, Delete) \uc791\uc5c5\uc744 \ub354 \uc27d\uac8c \uc218\ud589\ud560 \uc218 \uc788\ub3c4\ub85d \ub9cc\ub4e0 \ubaa8\ub4c8\uc785\ub2c8\ub2e4. \uae30\ubcf8\uc801\uc73c\ub85c JPA\ub97c \uc0ac\uc6a9\ud560 \ub54c \uadc0\ucc2e\uc740 \uc124\uc815\uacfc \ucf54\ub4dc\ub97c \ucd5c\uc18c\ud654\ud558\uace0, \uac1c\ubc1c\uc790\uac00 \ubcf4\ub2e4 \uc801\uc740 \ub178\ub825\uc73c\ub85c \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc640 \uc0c1\ud638\uc791\uc6a9\ud560 \uc218 \uc788\uac8c \ud574\uc90d\ub2c8\ub2e4.<\/p>\n JPA\ub294 \uc5d4\ud2f0\ud2f0 \ud074\ub798\uc2a4\uc640 \ub370\uc774\ud130\ubca0\uc774\uc2a4 \ud14c\uc774\ube14 \uac04\uc758 \ub9e4\ud551\uc744 \uc9c0\uc6d0\ud558\ub294\ub370, \uc774\ub97c \ud1b5\ud574 SQL \ucffc\ub9ac \uc5c6\uc774\ub3c4 \ub370\uc774\ud130\ubca0\uc774\uc2a4\ub97c \uc27d\uac8c \uc870\uc791\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub294 JPA\uc758 \uc778\ud130\ud398\uc774\uc2a4\ub97c \uc81c\uacf5\ud558\uc5ec \uac1c\ubc1c\uc790\uac00 \uc2e4\uc81c\ub85c \ud65c\uc6a9\ud560 \uc218 \uc788\uac8c \ud569\ub2c8\ub2e4.<\/p>\n<\/section>\n ORM(Object-Relational Mapping)\uc740 \uac1d\uccb4 \uc9c0\ud5a5 \ud504\ub85c\uadf8\ub798\ubc0d \uc5b8\uc5b4\uc5d0\uc11c \uc0ac\uc6a9\ud558\ub294 \uac1d\uccb4\uc640 \uad00\uacc4\ud615 \ub370\uc774\ud130\ubca0\uc774\uc2a4 \uac04\uc758 \ub370\uc774\ud130 \ubcc0\ud658\uc744 \uc790\ub3d9\uc73c\ub85c \ucc98\ub9ac\ud574\uc8fc\ub294 \uae30\uc220\uc785\ub2c8\ub2e4. \uad00\uacc4\ud615 \ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \ud14c\uc774\ube14 \uad6c\uc870\ub85c \ub370\uc774\ud130\ub97c \uc800\uc7a5\ud558\ub294 \ubc18\uba74, \uac1d\uccb4 \uc9c0\ud5a5 \ud504\ub85c\uadf8\ub798\ubc0d\uc5d0\uc11c\ub294 \ud074\ub798\uc2a4\uc640 \uac1d\uccb4\ub85c \ub370\uc774\ud130\ub97c \ucc98\ub9ac\ud569\ub2c8\ub2e4. ORM\uc740 \uc774 \ub450 \uac00\uc9c0 \uac04\uadf9\uc744 \uba54\uc6cc\uc8fc\ub294 \uc5ed\ud560\uc744 \ud569\ub2c8\ub2e4.<\/p>\n JPA(Java Persistence API)\ub294 \uc790\ubc14 \uc9c4\uc601\uc5d0\uc11c ORM\uc744 \uc704\ud55c \uc778\ud130\ud398\uc774\uc2a4\uc785\ub2c8\ub2e4. JPA\ub294 \ub370\uc774\ud130\ubca0\uc774\uc2a4 \uc791\uc5c5\uc5d0 \ud544\uc694\ud55c API\ub97c \uc815\uc758\ud558\uc5ec \uac1c\ubc1c\uc790\uac00 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc640 \uc0c1\ud638\uc791\uc6a9\ud560 \uc218 \uc788\ub3c4\ub85d \ub3d5\uc2b5\ub2c8\ub2e4. JPA\ub294 \ub2e4\uc74c\uacfc \uac19\uc740 \uc8fc\uc694 \uac1c\ub150\uc744 \ud3ec\ud568\ud569\ub2c8\ub2e4:<\/p>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub294 JPA\uc758 \uae30\ub2a5\uc744 \ud655\uc7a5\ud558\uc5ec \ub2e4\uc74c\uacfc \uac19\uc740 \uc8fc\uc694 \ud2b9\uc9d5\uc744 \uc81c\uacf5\ud569\ub2c8\ub2e4:<\/p>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub97c \uc0ac\uc6a9\ud558\uae30 \uc704\ud574\uc11c\ub294 \uc2a4\ud504\ub9c1 \ubd80\ud2b8 \ud504\ub85c\uc81d\ud2b8\ub97c \uc124\uc815\ud574\uc57c \ud569\ub2c8\ub2e4.<\/p>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub97c \ud504\ub85c\uc81d\ud2b8\uc5d0 \ucd94\uac00\ud558\uae30 \uc704\ud574 pom.xml \ud30c\uc77c\uc5d0 \ub2e4\uc74c \uc758\uc874\uc131\uc744 \ucd94\uac00\ud569\ub2c8\ub2e4:<\/p>\n \ub370\uc774\ud130\ubca0\uc774\uc2a4 \uc5f0\uacb0\uc744 \uc704\ud574 application.properties \ud30c\uc77c\uc5d0 \ub2e4\uc74c\uacfc \uac19\uc740 \uc124\uc815\uc744 \ucd94\uac00\ud569\ub2c8\ub2e4:<\/p>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub97c \uc0ac\uc6a9\ud558\uae30 \uc704\ud574 \uc5d4\ud2f0\ud2f0 \ud074\ub798\uc2a4\ub97c \uc815\uc758\ud558\uace0, \uc774\ub97c \ub2e4\ub8e8\uae30 \uc704\ud55c \ub9ac\ud3ec\uc9c0\ud1a0\ub9ac\ub97c \uc0dd\uc131\ud569\ub2c8\ub2e4.<\/p>\n \uc544\ub798\ub294 \uac04\ub2e8\ud55c ‘User’ \uc5d4\ud2f0\ud2f0\ub97c \uc815\uc758\ud55c \uc608\uc785\ub2c8\ub2e4:<\/p>\n \ub9ac\ud3ec\uc9c0\ud1a0\ub9ac \uc778\ud130\ud398\uc774\uc2a4\ub294 JpaRepository\ub97c \uc0c1\uc18d\ubc1b\uc544 CRUD \uc791\uc5c5\uc744 \uc218\ud589\ud569\ub2c8\ub2e4:<\/p>\n \ub9ac\ud3ec\uc9c0\ud1a0\ub9ac\ub97c \uc0ac\uc6a9\ud558\uc5ec \ube44\uc988\ub2c8\uc2a4 \ub85c\uc9c1\uc744 \ucc98\ub9ac\ud558\ub294 \uc11c\ube44\uc2a4 \ud074\ub798\uc2a4\uc640 \uc774\ub97c \ud638\ucd9c\ud558\ub294 REST API\ub97c \uad6c\ud604\ud558\ub294 \ucee8\ud2b8\ub864\ub7ec \ud074\ub798\uc2a4\ub97c \ucd94\uac00\ud569\ub2c8\ub2e4.<\/p>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub97c \ud1b5\ud574 \uc2e4\uc81c \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c \uc5b4\ub5bb\uac8c \ub370\uc774\ud130\ub97c \ucc98\ub9ac\ud558\ub294\uc9c0\uc5d0 \ub300\ud55c \uc608\uc2dc\ub97c \uc0b4\ud3b4\ubcf4\uaca0\uc2b5\ub2c8\ub2e4.<\/p>\n \uc0ac\uc6a9\uc790\ub97c \uc0dd\uc131\ud558\uae30 \uc704\ud574 REST API \uc694\uccad\uc744 \ubcf4\ub0c5\ub2c8\ub2e4:<\/p>\n \ud2b9\uc815 \uc0ac\uc6a9\uc790\uc758 \uc815\ubcf4\ub97c \uc870\ud68c\ud558\ub294 \uc694\uccad\uc744 \ubcf4\ub0c5\ub2c8\ub2e4:<\/p>\n \uc704\uc758 \uc694\uccad\uc744 \ud1b5\ud574 ID\uac00 1\uc778 \uc0ac\uc6a9\uc790\uc758 \uc815\ubcf4\ub97c JSON \ud615\ud0dc\ub85c \ubc1b\uc744 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/p>\n<\/section>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub97c \uc0ac\uc6a9\ud560 \ub54c \uc131\ub2a5 \uc774\uc288\ub97c \ud574\uacb0\ud558\uae30 \uc704\ud55c \uba87 \uac00\uc9c0 \ubc29\ubc95\uc744 \uc54c\uc544\ubcf4\uaca0\uc2b5\ub2c8\ub2e4.<\/p>\n N+1 \ubb38\uc81c\ub294 \uc5f0\uad00\ub41c \uc5d4\ud2f0\ud2f0\ub97c \ucffc\ub9ac\ud560 \ub54c \ubc1c\uc0dd\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \uc774\ub97c \ud574\uacb0\ud558\uae30 \uc704\ud574 FetchType.LAZY\uc640 FetchType.EAGER\ub97c \uc801\uc808\ud788 \ud65c\uc6a9\ud574\uc57c \ud569\ub2c8\ub2e4.<\/p>\n \ub370\uc774\ud130\uac00 \ub9ce\uc744 \uacbd\uc6b0 \ubc30\uce58 \ucc98\ub9ac\ub97c \ud1b5\ud574 \uc131\ub2a5\uc744 \uac1c\uc120\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \uc774\ub294 \ud55c \ubc88\uc5d0 \ub300\ub7c9\uc758 \ub370\uc774\ud130\ub97c \ucc98\ub9ac\ud558\uc5ec \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 \ubd80\ud558\ub97c \uc904\uc774\ub294 \ubc29\ubc95\uc785\ub2c8\ub2e4.<\/p>\n<\/section>\n \uc774\ubc88 \uac15\uc88c\uc5d0\uc11c\ub294 \uc2a4\ud504\ub9c1 \ubd80\ud2b8\ub97c \uae30\ubc18\uc73c\ub85c \ud55c \ubc31\uc5d4\ub4dc \uac1c\ubc1c\uc5d0\uc11c \ud575\uc2ec\uc801\uc778 \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\uc5d0 \ub300\ud55c \uac1c\ub150\uacfc \uc0ac\uc6a9\ubc95, \uadf8\ub9ac\uace0 \ud658\uacbd \uc124\uc815 \ubc29\ubc95\uc5d0 \ub300\ud574 \uc0b4\ud3b4\ubcf4\uc558\uc2b5\ub2c8\ub2e4. \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub294 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc640\uc758 \ud1b5\uc2e0\uc744 \ub2e8\uc21c\ud654\ud558\uace0, \uac1c\ubc1c\uc790\uc758 \uc0dd\uc0b0\uc131\uc744 \ud06c\uac8c \ud5a5\uc0c1\uc2dc\ucf1c\uc8fc\ub294 \ub3c4\uad6c\uc785\ub2c8\ub2e4.<\/p>\n \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\uc758 \ub2e4\uc591\ud55c \uae30\ub2a5\uc744 \ud65c\uc6a9\ud558\uc5ec \ub354\uc6b1 \ud6a8\uc728\uc801\uc778 \ubc31\uc5d4\ub4dc \uc2dc\uc2a4\ud15c\uc744 \uad6c\ucd95\ud574\ubcf4\uc138\uc694. \ucd94\uac00\uc801\uc778 \uc9c8\ubb38\uc774\ub098 \ud53c\ub4dc\ubc31\uc774 \uc788\uc73c\uc2dc\uba74 \ub313\uae00\ub85c \ub0a8\uaca8\uc8fc\uc2dc\uae30 \ubc14\ub78d\ub2c8\ub2e4. \uac10\uc0ac\ud569\ub2c8\ub2e4!<\/p>\n<\/section>\n<\/article>\n <\/body><\/p>\n","protected":false},"excerpt":{"rendered":"1. \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\ub780?<\/h2>\n
2. JPA\uc758 \uae30\ubcf8 \uac1c\ub150<\/h2>\n
2.1 ORM\uc774\ub780?<\/h3>\n
2.2 JPA\uc758 \uc815\uc758<\/h3>\n
\n
3. \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\uc758 \ud2b9\uc9d5<\/h2>\n
\n
4. \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA \ud658\uacbd \uc124\uc815<\/h2>\n
4.1 Maven \uc758\uc874\uc131 \ucd94\uac00<\/h3>\n
\n
<dependency>\n <groupId>org.springframework.boot<\/groupId>\n <artifactId>spring-boot-starter-data-jpa<\/artifactId>\n<\/dependency>\n\n<dependency>\n <groupId>com.h2database<\/groupId>\n <artifactId>h2<\/artifactId>\n <scope>runtime<\/scope>\n<\/dependency><\/code>\n <\/pre>\n4.2 application.properties \uc124\uc815<\/h3>\n
\n
spring.datasource.url=jdbc:h2:mem:testdb\nspring.datasource.driver-class-name=org.h2.Driver\nspring.datasource.username=sa\nspring.datasource.password=password\nspring.h2.console.enabled=true\nspring.jpa.hibernate.ddl-auto=update<\/code>\n <\/pre>\n<\/section>\n5. \uc5d4\ud2f0\ud2f0 \ud074\ub798\uc2a4 \ubc0f \ub9ac\ud3ec\uc9c0\ud1a0\ub9ac \uc0dd\uc131<\/h2>\n
5.1 \uc5d4\ud2f0\ud2f0 \ud074\ub798\uc2a4 \uc815\uc758<\/h3>\n
\n
import javax.persistence.*;\n\n@Entity\n@Table(name=\"users\")\npublic class User {\n @Id\n @GeneratedValue(strategy = GenerationType.IDENTITY)\n private Long id;\n\n private String name;\n private String email;\n\n \/\/ Getters and Setters\n}<\/code>\n <\/pre>\n5.2 \ub9ac\ud3ec\uc9c0\ud1a0\ub9ac \uc778\ud130\ud398\uc774\uc2a4 \uc815\uc758<\/h3>\n
\n
import org.springframework.data.jpa.repository.JpaRepository;\n\npublic interface UserRepository extends JpaRepository<User, Long> {\n User findByEmail(String email);\n}<\/code>\n <\/pre>\n<\/section>\n6. \uc11c\ube44\uc2a4 \ud074\ub798\uc2a4 \ubc0f \ucee8\ud2b8\ub864\ub7ec \uc0dd\uc131<\/h2>\n
6.1 \uc11c\ube44\uc2a4 \ud074\ub798\uc2a4 \uc815\uc758<\/h3>\n
\n
import org.springframework.beans.factory.annotation.Autowired;\nimport org.springframework.stereotype.Service;\nimport java.util.List;\n\n@Service\npublic class UserService {\n @Autowired\n private UserRepository userRepository;\n\n public List<User> findAll() {\n return userRepository.findAll();\n }\n\n public User findById(Long id) {\n return userRepository.findById(id).orElse(null);\n }\n\n public User save(User user) {\n return userRepository.save(user);\n }\n}<\/code>\n <\/pre>\n6.2 \ucee8\ud2b8\ub864\ub7ec \ud074\ub798\uc2a4 \uc815\uc758<\/h3>\n
\n
import org.springframework.beans.factory.annotation.Autowired;\nimport org.springframework.web.bind.annotation.*;\n\nimport java.util.List;\n\n@RestController\n@RequestMapping(\"\/api\/users\")\npublic class UserController {\n @Autowired\n private UserService userService;\n\n @GetMapping\n public List<User> getAllUsers() {\n return userService.findAll();\n }\n\n @PostMapping\n public User createUser(@RequestBody User user) {\n return userService.save(user);\n }\n}<\/code>\n <\/pre>\n<\/section>\n7. \uc2a4\ud504\ub9c1 \ub370\uc774\ud130 JPA\uc758 \uc0ac\uc6a9 \uc608\uc2dc<\/h2>\n
7.1 \uc0ac\uc6a9\uc790 \uc0dd\uc131 \uc694\uccad<\/h3>\n
\n
POST \/api\/users\nContent-Type: application\/json\n\n{\n \"name\": \"\ud64d\uae38\ub3d9\",\n \"email\": \"hong@example.com\"\n}<\/code>\n <\/pre>\n7.2 \uc0ac\uc6a9\uc790 \uc870\ud68c \uc694\uccad<\/h3>\n
\n
GET \/api\/users\/1<\/code>\n <\/pre>\n8. \uc131\ub2a5 \ucd5c\uc801\ud654<\/h2>\n
8.1 N+1 \ubb38\uc81c \ud574\uacb0<\/h3>\n
8.2 \ubc30\uce58 \ucc98\ub9ac<\/h3>\n
9. \uacb0\ub860<\/h2>\n