[Spring] 회원가입 이메일 인증 구현: JavaMailSender와 보안 설정

@Service
public class MailService {
  private final JavaMailSender mailSender;

  public MailService(JavaMailSender mailSender) {
    this.mailSender = mailSender;
  }

  public void sendAuthMail(String to, String link) throws MessagingException {
    MimeMessage message = mailSender.createMimeMessage();
    MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
    helper.setTo(to);
    helper.setSubject("[이메일 인증]");
    helper.setText("<p>아래 링크로 인증을 완료하세요.</p><a href='" + link + "'>인증하기</a>", true);
    mailSender.send(message);
  }
}

// MailHandler.java
public class MailHandler { // 메일보내기 유틸 클래스
	private JavaMailSender mailSender;
	private MimeMessage message;
	private MimeMessageHelper messageHelper;

	public MailHandler(JavaMailSender mailSender) throws MessagingException {
		this.mailSender = mailSender;
		message = this.mailSender.createMimeMessage();
		messageHelper = new MimeMessageHelper(message, true, "UTF-8");
	}

	public void setSubject(String subject) throws MessagingException {
		messageHelper.setSubject(subject);
	}

	public void setText(String htmlContent) throws MessagingException {
		messageHelper.setText(htmlContent, true);
	}

	public void setFrom(String email, String name) throws UnsupportedEncodingException, MessagingException {
		messageHelper.setFrom(email, name);
	}

	public void setTo(String email) throws MessagingException {
		messageHelper.setTo(email);
	}

	public void addInline(String contentId, DataSource dataSource) throws MessagingException {
		messageHelper.addInline(contentId, dataSource);
	}

	public void send() {
		mailSender.send(message);
	}

}

// TempKey.java
public class TempKey { // 인증키 생성 클래스
	private boolean lowerCheck;
	private int size;

	public String getKey(int size, boolean lowerCheck) {
		this.size = size;
		this.lowerCheck = lowerCheck;
		return init();
	}

	private String init() {
		Random ran = new Random();
		StringBuffer sb = new StringBuffer();
		int num = 0;
		do {
			num = ran.nextInt(75) + 48;
			if ((num >= 48 && num <= 57) || (num >= 65 && num <= 90) || (num >= 97 && num <= 122)) {
				sb.append((char) num);
			} else {
				continue;
			}
		} while (sb.length() < size);
		if (lowerCheck) {
			return sb.toString().toLowerCase();
		}
		return sb.toString();
	}

}

// dao
@Override
public void createAuthKey(String userEmail, String authKey) throws Exception { // 인증키 DB에 넣기
	Map<String, Object> map = new HashMap<String, Object>();

	map.put("userEmail", userEmail);
	map.put("authKey", authKey);

	session.selectOne(namespace + ".createAuthKey", map);
}

@Override
public void userAuth(String userEmail) throws Exception { // 인증키 일치시 DB칼럼(인증여부) false->true 로 변경
	session.update(namespace + ".userAuth", userEmail);
}

// service
@Transactional
@Override
public void create(UserVO vo) throws Exception {
	dao.create(vo); // 회원가입 DAO
	String key = new TempKey().getKey(50, false); // 인증키 생성
	dao.createAuthKey(vo.getUserEmail(), key); // 인증키 DB저장
	MailHandler sendMail = new MailHandler(mailSender);
	sendMail.setSubject("[홈페이지 이메일 인증]"); // 메일제목
	sendMail.setText( // 메일내용
			"<h1>메일인증</h1>" +
			"<a href='http://localhost/user/emailConfirm?userEmail=" + vo.getUserEmail() +
			"&key=" + key +
			"' target='_blenk'>이메일 인증 확인</a>");
	sendMail.setFrom("아이디@gmail.com", "보낼사람 이름"); // 보낸이
	sendMail.setTo(vo.getUserEmail()); // 받는이
	sendMail.send();
}

@Override
public void userAuth(String userEmail) throws Exception {
	dao.userAuth(userEmail);
}

// controller
@RequestMapping(value = "/regUser", method = RequestMethod.GET) // 회원가입창 보기
public String registerGet() throws Exception {
	return "/user/userJoin";
}

@RequestMapping(value = "/regUser", method = RequestMethod.POST)
public String registerPost(UserVO vo, RedirectAttributes rttr) throws Exception { // 회원가입하기
	service.create(vo);
	rttr.addFlashAttribute("msg", "regSuccess");

	return "redirect:/";
}

@RequestMapping(value = "/emailConfirm", method = RequestMethod.GET)
public String emailConfirm(String userEmail, Model model) throws Exception { // 이메일 인증 확인창
		service.userAuth(userEmail);
		model.addAttribute("userEmail", userEmail);

		return "/user/emailConfirm"; // emailConfirm.jsp
}