Email Verifier Util

public class VerifyEmailUtil {
	
	private static Logger logger = LoggerFactory.getLogger(VerifyEmailUtil.class);

	private static final String EMAIL_REGEX = new StringBuffer().append("^([a-zA-Z0-9_.+-]").append("|").append("[")
			.append("`").append("~").append("!").append("#").append("$").append("%").append("^").append("&").append("*").append("=")
			.append(",").append(".").append("<").append(">").append(";").append(":").append("'").append("\"").append("")
			.append("\\[").append("\\]").append("\\(").append("\\)").append("\\{").append("\\}").append("\\|").append("\\").append("\\/")
			.append("]").append(")+").append("@(([a-zA-Z0-9-])+.)+").append("([a-zA-Z0-9]{2,4})+$").toString();
			
	//"^([a-zA-Z0-9_.+-]|[*`~!#%&=,.<>;:'"?$^\[\]\(\)\{\}\|\\\/])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$";
	
	private static final String EMAIL_DOMAIN_REGEX = "@(?:[\\w](?:[\\w-]*[\\w])?\\.)+[\\w](?:[\\w-]*[\\w])?";
	
	private static Record[] records = null;
	
	private static List<String> domainWhiteList = null;
	
	static {
		domainWhiteList = Arrays.asList(ConfigProperties.getInstance().getValue("domain_whitelist").split(","));
	}
	
	/**
	 * 语法检验
	 * @param email
	 * @return
	 */
	public static boolean isValidFormat(String email) {
		if (StringUtils.isEmpty(email)) {
			return false;
		}
		if (Pattern.matches(EMAIL_REGEX, email)) {
			// 语法校验通过
			return true;
		} else {
			// 语法校验未通过
			return false;
		}
	}
	
	/**
	 * 域名语法校验
	 * @param domain
	 * @return
	 */
	public static boolean isValidDomainFormat(String domain) {
		if (StringUtils.isEmpty(domain)) {
			return false;
		}
		if (Pattern.matches(EMAIL_DOMAIN_REGEX, domain)) {
			// 语法校验通过
			return true;
		} else {
			// 语法校验未通过
			return false;
		}
	}
	
	/**
	 * 是否存在白名单种
	 * @param domain
	 * @return
	 */
	public static boolean isInDomainWhiteList(String domain) {
		if (domainWhiteList.contains(domain)) {
			return true;// 存在域名白名单中，直接跳过
		} 
		return false;
	}
	
	/**
	 * MX记录分析
	 * @param email
	 * @return
	 */
	public static boolean isValidDomain(String email) {
		String domain = email.split(StringConstant.AT)[1].toLowerCase();
		Lookup lookup = null;
		try {
			lookup = new Lookup(domain, Type.MX);
		} catch (TextParseException e) {
			logger.error(e.getMessage(), e);
		}
		lookup.run();
		if (lookup.getResult() != Lookup.SUCCESSFUL) {
			// 找不到MX记录
			logger.info(domain + "'s mx not exists.");
			return false;
		} else {
			// MX记录存在
			logger.info(domain + "'s mx exists.");
			records = lookup.getAnswers();
			/*if (!ArrayUtils.isEmpty(records)) {
				for (Record record : records) {
					logger.info(email + "'s MX record: " + record.getAdditionalName().toString());
				}
			}*/
			return true;
		}
	}
	
	/**
	 * SMTP
	 * @param email
	 * @return
	 */
	public static boolean isValidUser(String email) {
		final String SENDER_EMAIL = "no-reply@qq.com";
		final String SENDER_EMAIL_DOMAIN = SENDER_EMAIL.split(StringConstant.AT)[1];
		if (!ArrayUtils.isEmpty(records)) {
			int count = 0;// 计数器
			SMTPClient client = new SMTPClient(); 
			for (Record record : records) {
				String hostname =  record.getAdditionalName().toString();
				try {
					client.connect(hostname);// 连接到接收邮箱地址的邮箱服务器  
				} catch (Exception e) {
					count++;
					if (count >= records.length) {
						// 如果由MX得到的result服务器都连接不上,则判定email无效
						return false;
					}
				}
				if (!SMTPReply.isPositiveCompletion(client.getReplyCode())) {
					// 服务器通信失败
					try {
						client.disconnect();
						continue;
					} catch (Exception e) {
						logger.error(e.getMessage(), e);
					}
				} else {
					logger.info("MX record about " + hostname + "exists. ");
					logger.info("Connection succeeded to " + hostname + " SMTP.");
					logger.info(client.getReplyString());
					try {
						client.login(SENDER_EMAIL_DOMAIN);
						logger.info("> HELO " + hostname);
						logger.info(client.getReplyString());
						client.setSender(SENDER_EMAIL);
						if (client.getReplyCode() != 250) {
							client.disconnect();
							continue;
						}
					} catch (Exception e) {
						logger.error(e.getMessage(), e);
					}
					logger.info("> MAIL FROM: <" + SENDER_EMAIL + ">");
					logger.info(client.getReplyString());
					try {
						client.disconnect();
						continue;
					} catch (Exception e) {
						logger.error(e.getMessage(), e);
					}
					logger.info("> RCPT TO: <" + email + ">");
					logger.info(client.getReplyString());
					
					if (client.getReplyCode() == 250) {
						// SMTP通讯成功
						return true;
					}
					try {
						client.disconnect();
						continue;
					} catch (Exception e) {
						logger.error(e.getMessage(), e);
					}
				}
			}
		} else {
			// SMTP失败
			return false;
		}
		return false;
	}
	
	public static void main(String[] args) {
		System.out.println(isValidFormat("*********@qq.com"));
		System.out.println(isValidFormat("$---@qq.com"));
		System.out.println(isValidFormat("#*****$@qq.com"));
		System.out.println(isValidFormat("!123******@qq.com"));
		System.out.println(isValidDomain("@qq.com"));
		System.out.println(isValidDomainFormat("@aapindustries.com.au"));
	}
}