正则表达式判断身份证和提取生日

public class IDCardUtil {

	public static boolean isValidIdCard(String idCard) {

		if (idCard == null) {
			return false;
		}

		Pattern p = Pattern.compile("(\\d{17}[0-9a-zA-Z]|\\d{14}[0-9a-zA-Z])");

		return p.matcher(idCard).matches();
	}

	public static String getBirthday(String idCard) {
		if (idCard == null) {
			return null;
		}
		Pattern p1 = Pattern.compile("\\d{6}(\\d{8}).*"); // 用于提取出生日字符串
		Pattern p2 = Pattern.compile("(\\d{4})(\\d{2})(\\d{2})");// 用于将生日字符串进行分解为年月日

		Matcher matcher = p1.matcher(idCard);
		if (matcher.find()) {
			String birthday = matcher.group(1);
			Matcher matcher2 = p2.matcher(birthday);
			if (matcher2.find()) {
				StringBuilder sb = new StringBuilder();
				sb.append(matcher2.group(1));
				sb.append('-');
				sb.append(matcher2.group(2));
				sb.append('-');
				sb.append(matcher2.group(3));
				return sb.toString();
			}
		}

		return null;
	}
}