feat: 회원 등록 기능 추가

src/main/java/org/c4marathon/assignment/controller/UserController.java

@@ -0,0 +1,25 @@
+package org.c4marathon.assignment.controller;
+
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.c4marathon.assignment.dto.request.PostUserReq;
+import org.c4marathon.assignment.service.UserService;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/v1/users")
+@RequiredArgsConstructor
+public class UserController {
+    private final UserService userService;
+
+    @PostMapping()
+    public ResponseEntity<Void> registerUser(@RequestBody @Valid PostUserReq postUserReq) {
+        userService.registerUser(postUserReq);
+        return ResponseEntity.status(HttpStatus.CREATED).build();
+    }
+}

src/main/java/org/c4marathon/assignment/dto/request/PostUserReq.java

@@ -0,0 +1,20 @@
+package org.c4marathon.assignment.dto.request;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+
+public record PostUserReq(
+        @Size(max = 100)
+        @NotBlank
+        String username,
+
+        @Email
+        @NotBlank
+        String email,
+
+        @Size(max = 100)
+        @NotBlank
+        String nickname
+) {
+}

src/main/java/org/c4marathon/assignment/repository/UserJpaRepository.java

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+package org.c4marathon.assignment.repository;
+
+import org.c4marathon.assignment.entity.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface UserJpaRepository extends JpaRepository<User, Long> {
+	boolean existsByEmail(String email);
+}

src/main/java/org/c4marathon/assignment/repository/UserRepository.java

@@ -0,0 +1,20 @@
+package org.c4marathon.assignment.repository;
+
+import lombok.RequiredArgsConstructor;
+
+import org.c4marathon.assignment.entity.User;
+import org.springframework.stereotype.Repository;
+
+@Repository
+@RequiredArgsConstructor
+public class UserRepository {
+	private final UserJpaRepository userJpaRepository;
+
+	public boolean isEmailExist(String email) {
+		return userJpaRepository.existsByEmail(email);
+	}
+
+	public User save(User user) {
+		return userJpaRepository.save(user);
+	}
+}

src/main/java/org/c4marathon/assignment/service/UserService.java

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+package org.c4marathon.assignment.service;
+
+import lombok.RequiredArgsConstructor;
+import org.c4marathon.assignment.dto.request.PostUserReq;
+import org.c4marathon.assignment.entity.Account;
+import org.c4marathon.assignment.entity.User;
+import org.c4marathon.assignment.exception.CustomException;
+import org.c4marathon.assignment.exception.ErrorCode;
+import org.c4marathon.assignment.repository.AccountRepository;
+import org.c4marathon.assignment.repository.UserRepository;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+public class UserService {
+    private final UserRepository userRepository;
+    private final AccountRepository accountRepository;
+
+    @Transactional
+    public void registerUser(PostUserReq postUserReq) {
+        if (isEmailExist(postUserReq.email())) {
+            throw new CustomException(ErrorCode.DUPLICATED_EMAIL);
+        }
+
+        User user = userRepository.save(User.builder()
+                .username(postUserReq.username())
+                .email(postUserReq.email())
+                .nickname(postUserReq.nickname())
+                .build());
+
+        Account mainAccount = new Account(user.getId());
+        accountRepository.save(mainAccount);
+    }
+
+    public boolean isEmailExist(String email) {
+        return userRepository.isEmailExist(email);
+    }
+}