feat: 닉네임 조회 기능 구현

build.gradle

@@ -22,8 +22,11 @@ repositories {
 }
 
 dependencies {
+	implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
 	implementation 'org.springframework.boot:spring-boot-starter-web'
 	compileOnly 'org.projectlombok:lombok'
+	implementation 'mysql:mysql-connector-java:8.0.33'
+	runtimeOnly 'com.mysql:mysql-connector-j'
 	annotationProcessor 'org.projectlombok:lombok'
 	testImplementation 'org.springframework.boot:spring-boot-starter-test'
 }

src/main/java/com/app3/server/user/controller/UserController.java

@@ -0,0 +1,28 @@
+package com.app3.server.user.controller;
+
+import com.app3.server.user.controller.dto.response.UserGetResponse;
+import com.app3.server.user.repository.UserJpaRepository;
+import com.app3.server.user.service.UserService;
+import jakarta.persistence.EntityNotFoundException;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/user")
+@RequiredArgsConstructor
+public class UserController {
+
+    private final UserService userService;
+
+    // 목록 조회
+    @GetMapping("/{id}")
+    public ResponseEntity<UserGetResponse> getUserProfile(@PathVariable Long id) {
+        return ResponseEntity.ok(userService.getUserById(id));
+    }
+}

src/main/java/com/app3/server/user/controller/dto/response/UserGetResponse.java

@@ -0,0 +1,15 @@
+package com.app3.server.user.controller.dto.response;
+
+import com.app3.server.user.domain.User;
+
+public record UserGetResponse (
+        String nickname
+) {
+    public static UserGetResponse of(User user) {
+        return new UserGetResponse(
+                user.getNickname()
+        );
+    }
+}
+
+

src/main/java/com/app3/server/user/domain/User.java

@@ -0,0 +1,28 @@
+package com.app3.server.user.domain;
+
+import lombok.AccessLevel;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+
+@Entity
+@Getter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class User {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+    private String nickname;
+
+
+    @Builder
+    public User(String nickname) {
+        this.nickname = nickname;
+    }
+}

src/main/java/com/app3/server/user/repository/UserJpaRepository.java

@@ -0,0 +1,13 @@
+package com.app3.server.user.repository;
+
+
+import com.app3.server.user.domain.User;
+import jakarta.persistence.EntityNotFoundException;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface UserJpaRepository extends JpaRepository<User, Long> {
+    default User findByIdOrThrow(Long id) {
+        return findById(id).orElseThrow(
+                () -> new EntityNotFoundException("회원이 존재하지 않습니다."));
+    }
+}

src/main/java/com/app3/server/user/service/UserService.java

@@ -0,0 +1,23 @@
+package com.app3.server.user.service;
+
+import com.app3.server.user.controller.dto.response.UserGetResponse;
+import com.app3.server.user.domain.User;
+import com.app3.server.user.repository.UserJpaRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Transactional
+@Service
+@RequiredArgsConstructor
+public class UserService {
+    private final UserJpaRepository userJpaRepository;
+
+    public UserGetResponse getUserById(Long id) {
+        return UserGetResponse.of(userJpaRepository.findByIdOrThrow(id));
+    }
+}
+

src/main/resources/application-local.yaml

@@ -0,0 +1,15 @@
+spring:
+  datasource:
+    driver-class-name: com.mysql.cj.jdbc.Driver
+    url: jdbc:mysql://localhost:3306/demo?serverTimezone=UTC&characterEncoding=UTF-8
+    username: root
+    password: sb03sb04!!
+
+  config:
+    activate:
+      on-profile: dev
+
+  jpa:
+    database-platform: org.hibernate.dialect.MySQL8Dialect
+    hibernate:
+      ddl-auto: create