[Java] Java Email(Gmail) 발송 가이드(Docker 활용)

import lombok.AllArgsConstructor;
import lombok.Getter;

@Getter
@AllArgsConstructor
public class GmailSendDto {
    private String to;
    private String isSuccess;
}

import com.plapp.indist_front_api.core.code.IsSuccess;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.List;
import java.util.Properties;

@Component
@Slf4j
public class EmailClient {
    @Value("${gmail.email}")
    private String EMAIL_ADDRESS;
    @Value("${gmail.password}")
    private String PASSWORD;

    public GmailSendDto sendEmail(String toEmail, String subject, String bodyText){
        String isSuccess = IsSuccess.SUCCESS.getCode();
        Session session = getSession();

        // Email 발송
        try {
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(EMAIL_ADDRESS));
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(toEmail));
            message.setSubject(subject); //메일 제목을 입력
            message.setText(bodyText);    //메일 내용을 입력
            Transport.send(message); ////전송
            log.info("[EMAIL SENT SUCCESS] Email: {}", toEmail);
        } catch (MessagingException e) {
            isSuccess = IsSuccess.FAIL.getCode();
            log.error("[EMAIL SENT ERROR] Email: {} \tReason: {}", toEmail, e.getMessage());
        }

        // Email 발송 결과 반환
        return new GmailSendDto(toEmail, isSuccess);
    }

    private Session getSession() {
        // Email 발송을 위한 설정
        Properties prop = new Properties();
        prop.put("mail.smtp.host", "smtp.gmail.com");
        prop.put("mail.smtp.port", 465);
        prop.put("mail.smtp.auth", "true");
        prop.put("mail.smtp.ssl.enable", "true");
        prop.put("mail.smtp.ssl.trust", "smtp.gmail.com");
        return Session.getDefaultInstance(prop, new Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(EMAIL_ADDRESS, PASSWORD);
            }
        });
    }

    // 다중 발송
    public List<GmailSendDto> sendMultiEmail(List<String> toEmails, String subject, String bodyText){
        return List.of(
                toEmails.stream()
                        .map(toEmail -> sendEmail(toEmail, subject, bodyText))
                        .toArray(GmailSendDto[]::new)
        );
    }
}