[Spring Boot] Gmail SMTP 사용하기

◎ Gmail 설정

• 참고 자료

◎ property 설정

mail:
  smtp:
    host: smtp.gmail.com
    port: 587
    username: {{ gmail-ID }}
    password: {{ 기기용 앱 비밀번호 }}
    auth: true
    starttls:
      enable: true

◎ Email 보내기

• Configuration

  @Configuration
  public class EmailConfiguration {
  
      @Value("${mail.smtp.host}")
      private String host;
      @Value("${mail.smtp.port}")
      private int port;
      @Value("${mail.smtp.username}")
      private String username;
      @Value("${mail.smtp.password}")
      private String password;
      @Value("${mail.smtp.auth}")
      private String auth;
      @Value("${mail.smtp.starttls.enable}")
      private String tlsEnable;
  
      // EmailSendable은 상황마다 다르게 설정 
      @Bean
      @Primary
      public EmailSendable simpleEmailSender(){
          return new SimpleEmailSender(javaMailSender());
      }
  
      @Bean
      public JavaMailSender javaMailSender() {
          JavaMailSenderImpl mailSender = new JavaMailSenderImpl();
          mailSender.setHost(host);
          mailSender.setPort(port);
          mailSender.setUsername(username);
          mailSender.setPassword(password);
  
          Properties props = mailSender.getJavaMailProperties();
          props.put("mail.smtp.auth", auth);
          props.put("mail.smtp.starttls.enable", tlsEnable);
  
          return mailSender;
      }
  }

• Interface

  public interface EmailSendable {
      void send(String[] to, String subject, String Message) throws InterruptedException;
  }

• implements

  @AllArgsConstructor
  public class SimpleEmailSender implements EmailSendable{
  
      private final JavaMailSender javaMailSender;
  
      @Override
      public void send(String[] to, String subject, String message) throws InterruptedException {
          SimpleMailMessage mailMessage = new SimpleMailMessage();
          mailMessage.setTo(to);
          mailMessage.setText(message);
          mailMessage.setSubject(subject);
          mailMessage.setText(message);
          javaMailSender.send(mailMessage);
  
          System.out.println("Sent simple email!");
      }
  }

• Text 보내기

  @Service
  @AllArgsConstructor
  public class EmailSender {
      private final EmailSendable emailSendable;
  
      public void setMailSender(String[] to, String subject, String message) throws MailSendException,
              InterruptedException {
          emailSendable.send(to, subject, message);
      }
      public void setEmailSenderSendOne(String to, String subject, String message) throws MailSendException,
              InterruptedException{
          emailSendable.send(new String[]{to}, subject, message);
      }
  }

• 사용 예시

      @GetMapping("/send-mail")
      public String checkSendMail(@RequestParam String email) {
          String[] mail = new String[]{email};
          try{
              emailSender.setMailSender(mail, "TEAM17 이메일 전송 테스트입니다.", "TEAM17 이메일 전송 테스트입니다.");
          } catch (Exception e){
              throw new BusinessLogicException(ExceptionCode.FAIL_SEND_EMAIL);
          }
          return email + " 메일함 확인하세요.";
      }