[feat] 메일 발송 기능 구현

build.gradle

@@ -39,7 +39,9 @@ dependencies {
 	implementation 'org.springframework.boot:spring-boot-starter-data-redis'
 	implementation 'org.springframework.boot:spring-boot-starter-security'
 	implementation 'org.springframework.boot:spring-boot-starter-validation'
+	implementation 'org.springframework.boot:spring-boot-starter-mail'
 	implementation 'org.springframework.boot:spring-boot-starter-web'
+	implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
 	compileOnly 'org.projectlombok:lombok'
 	developmentOnly 'org.springframework.boot:spring-boot-devtools'
 	runtimeOnly 'com.oracle.database.jdbc:ojdbc11'
@@ -53,6 +55,9 @@ dependencies {
 	implementation 'com.google.auth:google-auth-library-oauth2-http:0.20.0'
 
 
+
+
+
 	implementation 'io.jsonwebtoken:jjwt-api:0.12.6'
 	runtimeOnly 'io.jsonwebtoken:jjwt-impl:0.12.6'
 	runtimeOnly 'io.jsonwebtoken:jjwt-jackson:0.12.6'

src/main/java/dmu/dasom/api/domain/applicant/repository/ApplicantRepository.java

@@ -1,18 +1,25 @@
 package dmu.dasom.api.domain.applicant.repository;
 
 import dmu.dasom.api.domain.applicant.entity.Applicant;
+import dmu.dasom.api.domain.applicant.enums.ApplicantStatus;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 
+import java.util.List;
+
 import java.util.Optional;
 
 public interface ApplicantRepository extends JpaRepository<Applicant, Long> {
 
     @Query("SELECT a FROM Applicant a ORDER BY a.id DESC")
     Page<Applicant> findAllWithPageRequest(final Pageable pageable);
 
+    // 상태별 지원자 조회
+    List<Applicant> findByStatus(ApplicantStatus status);
+    List<Applicant> findByStatusIn(List<ApplicantStatus> statuses);
+
     Optional<Applicant> findByStudentNo(final String studentNo);
 
 }

src/main/java/dmu/dasom/api/domain/applicant/service/ApplicantService.java

@@ -4,6 +4,7 @@
 import dmu.dasom.api.domain.applicant.dto.ApplicantDetailsResponseDto;
 import dmu.dasom.api.domain.applicant.dto.ApplicantResponseDto;
 import dmu.dasom.api.domain.applicant.dto.ApplicantStatusUpdateRequestDto;
+import dmu.dasom.api.domain.email.enums.MailType;
 import dmu.dasom.api.global.dto.PageResponse;
 
 public interface ApplicantService {
@@ -16,4 +17,6 @@ public interface ApplicantService {
 
     ApplicantDetailsResponseDto updateApplicantStatus(final Long id, final ApplicantStatusUpdateRequestDto request);
 
+    void sendEmailsToApplicants(MailType mailType);
+
 }

src/main/java/dmu/dasom/api/domain/applicant/service/ApplicantServiceImpl.java

@@ -5,18 +5,26 @@
 import dmu.dasom.api.domain.applicant.dto.ApplicantResponseDto;
 import dmu.dasom.api.domain.applicant.dto.ApplicantStatusUpdateRequestDto;
 import dmu.dasom.api.domain.applicant.entity.Applicant;
+import dmu.dasom.api.domain.applicant.enums.ApplicantStatus;
 import dmu.dasom.api.domain.applicant.repository.ApplicantRepository;
 import dmu.dasom.api.domain.common.exception.CustomException;
 import dmu.dasom.api.domain.common.exception.ErrorCode;
+import dmu.dasom.api.domain.email.enums.MailType;
+import dmu.dasom.api.domain.email.service.EmailService;
 import dmu.dasom.api.global.dto.PageResponse;
+import jakarta.mail.MessagingException;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.util.Optional;
 
+import java.util.List;
+
+@Slf4j
 @RequiredArgsConstructor
 @Service
 @Transactional
@@ -25,6 +33,7 @@ public class ApplicantServiceImpl implements ApplicantService {
     private final static int DEFAULT_PAGE_SIZE = 20;
 
     private final ApplicantRepository applicantRepository;
+    private final EmailService emailService;
 
     // 지원자 저장
     @Override
@@ -73,6 +82,35 @@ public ApplicantDetailsResponseDto updateApplicantStatus(final Long id, final Ap
         return applicant.toApplicantDetailsResponse();
     }
 
+    @Override
+    public void sendEmailsToApplicants(MailType mailType) {
+        List<Applicant> applicants;
+
+        // MailType에 따라 지원자 조회
+        switch (mailType) {
+            case DOCUMENT_RESULT:
+                applicants = applicantRepository.findAll();
+                break;
+            case FINAL_RESULT:
+                applicants = applicantRepository.findByStatusIn(
+                        List.of(ApplicantStatus.INTERVIEW_FAILED,
+                                ApplicantStatus.INTERVIEW_PASSED)
+                );
+                break;
+            default:
+                throw new CustomException(ErrorCode.INTERNAL_SERVER_ERROR);
+        }
+
+        for (Applicant applicant : applicants) {
+            try {
+                emailService.sendEmail(applicant.getEmail(), applicant.getName(), mailType);
+            } catch (MessagingException e) {
+                System.err.println("Failed to send email to: " + applicant.getEmail());
+            }
+        }
+    }
+
+
     // Repository에서 ID로 지원자 조회
     private Applicant findById(final Long id) {
         return applicantRepository.findById(id)

src/main/java/dmu/dasom/api/domain/common/exception/ErrorCode.java

@@ -20,6 +20,8 @@ public enum ErrorCode {
     WRITE_FAIL(400, "C011", "데이터를 쓰는데 실패하였습니다."),
     EMPTY_RESULT(400, "C012", "조회 결과가 없습니다."),
     DUPLICATED_STUDENT_NO(400, "C013", "이미 등록된 학번입니다."),
+    SEND_EMAIL_FAIL(400, "C014", "이메일 전송에 실패하였습니다."),
+    MAIL_TYPE_NOT_VALID(400, "C015", "메일 타입이 올바르지 않습니다.")
     ;
 
     private final int status;

src/main/java/dmu/dasom/api/domain/email/enums/MailType.java

@@ -0,0 +1,6 @@
+package dmu.dasom.api.domain.email.enums;
+
+public enum MailType {
+    DOCUMENT_RESULT, // 서류 합격
+    FINAL_RESULT // 최종 합격
+}

src/main/java/dmu/dasom/api/domain/email/service/EmailService.java

@@ -0,0 +1,62 @@
+package dmu.dasom.api.domain.email.service;
+
+import dmu.dasom.api.domain.common.exception.CustomException;
+import dmu.dasom.api.domain.common.exception.ErrorCode;
+import dmu.dasom.api.domain.email.enums.MailType;
+import jakarta.mail.MessagingException;
+import jakarta.mail.internet.MimeMessage;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.mail.javamail.JavaMailSender;
+import org.springframework.mail.javamail.MimeMessageHelper;
+import org.springframework.stereotype.Service;
+import org.thymeleaf.TemplateEngine;
+import org.thymeleaf.context.Context;
+
+@RequiredArgsConstructor
+@Service
+public class EmailService {
+
+    private JavaMailSender javaMailSender;
+    private TemplateEngine templateEngine;
+    @Value("${spring.mail.username}")
+    private String from;
+
+    public void sendEmail(String to, String name, MailType mailType) throws MessagingException {
+        if (mailType == null){
+            throw new CustomException(ErrorCode.MAIL_TYPE_NOT_VALID);
+        }
+        // 메일 제목 및 템플릿 설정
+        String subject;
+        String templateName = switch (mailType) {
+            case DOCUMENT_RESULT -> {
+                subject = "서류 합격 안내";
+                yield "document-pass-template";
+            }
+            case FINAL_RESULT -> {
+                subject = "최종 합격 안내";
+                yield "final-pass-template";
+            }
+            default -> throw new IllegalStateException("Unexpected value: " + mailType);
+        };
+
+        // HTML 템플릿에 전달할 데이터 설정
+        Context context = new Context();
+        context.setVariable("name", name); // 지원자 이름 전달
+
+        // HTML 템플릿 처리
+        String htmlBody = templateEngine.process(templateName, context);
+
+        // 이메일 생성 및 전송
+        MimeMessage message = javaMailSender.createMimeMessage();
+        MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
+
+        helper.setTo(to);
+        helper.setSubject(subject);
+        helper.setText(htmlBody, true);
+        helper.setFrom(from);
+
+        javaMailSender.send(message);
+    }
+
+}

src/main/java/dmu/dasom/api/global/admin/controller/AdminController.java

@@ -4,8 +4,10 @@
 import dmu.dasom.api.domain.applicant.dto.ApplicantResponseDto;
 import dmu.dasom.api.domain.applicant.dto.ApplicantStatusUpdateRequestDto;
 import dmu.dasom.api.domain.applicant.service.ApplicantService;
+import dmu.dasom.api.domain.email.enums.MailType;
 import dmu.dasom.api.global.dto.PageResponse;
 import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.Parameter;
 import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.ExampleObject;
 import io.swagger.v3.oas.annotations.media.Schema;
@@ -79,4 +81,34 @@ public ResponseEntity<ApplicantDetailsResponseDto> updateApplicantStatus(@PathVa
         return ResponseEntity.ok(applicantService.updateApplicantStatus(id, request));
     }
 
+    @Operation(
+            summary = "메일 전송",
+            description = "지원자들에게 서류 결과 또는 최종 결과 이메일을 발송합니다."
+    )
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "메일 전송 성공"),
+            @ApiResponse(responseCode = "400", description = "잘못된 요청",
+                    content = @Content(
+                            mediaType = "application/json",
+                            schema = @Schema(implementation = ErrorResponse.class),
+                            examples = {
+                                    @ExampleObject(
+                                            name = "전송 실패",
+                                            value = "{ \"code\": \"C014\", \"message\": \"이메일 전송에 실패하였습니다.\" }"
+                                    )
+                            }
+                    )
+            )
+    })
+    @PostMapping("/applicants/send-email")
+    public ResponseEntity<Void> sendEmailsToApplicants(
+            @RequestParam
+            @Parameter(description = "메일 발송 타입", examples = {
+                    @ExampleObject(name = "서류 합격 메일", value = "DOCUMENT_PASS"),
+                    @ExampleObject(name = "최종 결과 메일", value = "FINAL_RESULT")
+            }) MailType mailType) {
+        applicantService.sendEmailsToApplicants(mailType);
+        return ResponseEntity.ok().build();
+    }
+
 }

src/main/resources/application-credentials.yml

@@ -15,6 +15,17 @@ spring:
     redis:
       host: ${REDIS_HOST}
       port: ${REDIS_PORT}
+  mail:
+    host: smtp.gmail.com
+    port: 587
+    username: ${MAIL_USERNAME}
+    password: ${MAIL_PASSWORD}
+    properties:
+      mail:
+        smtp:
+          auth: true
+          starttls:
+            enable: true
 jwt:
   secret: ${JWT_SECRET}
   access-token-expiration: ${JWT_ACCESS_TOKEN_EXPIRATION}

src/main/resources/template/email-template.html

@@ -0,0 +1,79 @@
+<!DOCTYPE html>
+<html lang="ko">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>지원 결과 확인</title>
+    <style>
+        body {
+            font-family: Arial, sans-serif;
+            background-color: #1a1a1a;
+            color: #ffffff;
+            margin: 0;
+            padding: 0;
+        }
+        .container {
+            max-width: 600px;
+            margin: 0 auto;
+            padding: 20px;
+            background-color: #1a1a1a;
+            border-radius: 8px;
+            text-align: center;
+        }
+        .header {
+            font-size: 24px;
+            font-weight: bold;
+            color: #00B493;
+            margin-bottom: 20px;
+        }
+        .sub-header {
+            font-size: 16px;
+            background-color: #00B493;
+            padding: 10px;
+            border-radius: 5px;
+            margin-bottom: 20px;
+        }
+        .content {
+            font-size: 14px;
+            line-height: 1.8;
+        }
+        .content p {
+            margin-bottom: 10px;
+        }
+        .highlight {
+            color: #00B493;
+        }
+        .button {
+            display: inline-block;
+            background-color: #00B493;
+            color: #ffffff;
+            padding: 12px 24px;
+            border-radius: 5px;
+            text-decoration: none;
+            font-size: 16px;
+        }
+        .button:hover {
+            background-color: #00B493;
+        }
+    </style>
+</head>
+<body>
+<div class="container">
+    <!-- Header Section -->
+    <div class="header">DASOM</div>
+
+    <!-- Sub-header Section -->
+    <div class="sub-header">컴퓨터소프트웨어공학과 전공동아리 다솜<br>34기 서류 합격자 조회</div>
+
+    <!-- Content Section -->
+    <div class="content">
+        <p>안녕하세요, <span class="highlight" th:text="${name}"></span>님.</p>
+        <p>학번 마지막 <span class="highlight">4자리</span> + 전화번호 마지막 <span class="highlight">4자리</span>를 입력하여<br>지원 결과를 확인할 수 있습니다.</p>
+        <p>예시) <span class="highlight">08470542</span></p>
+
+        <!-- Button -->
+        <a href="https://example.com/result" class="button">결과 확인하기</a>
+    </div>
+</div>
+</body>
+</html>