StirngUtil工具类 之 邮箱注冊 域名不区分大写和小写方法

/**
	 * 传入邮箱域名所有变为小写，然后拼接前缀返回
	*<b>Summary: </b>
	* emailDomainTransform()
	* @param domain
	* @return
	 * @throws Exception 
	 */
	public static String emailDomainTransform(String email) throws Exception{
		if(email == null || "".equals(email.trim()) || email.indexOf("@") == -1){
			throw new Exception("验证邮箱地址错误");
		}
		String check = "^([a-z0-9A-Z]+[-|\.]?)+[a-z0-9A-Z]@([a-z0-9A-Z]+(-[a-z0-9A-Z]+)?\.)+[a-zA-Z]{2,}$";
		Pattern regex = Pattern.compile(check);
		Matcher matcher = regex.matcher(email);
		boolean flag = matcher.matches();
		if(flag){
			StringBuffer temp = new StringBuffer();
			temp.append(email.trim().substring(0, email.trim().indexOf("@")));
			temp.append((email.trim().indexOf("@") == email.trim().length() ?"":email.trim().substring(email.trim().indexOf("@"))).toLowerCase());
			return temp.toString(); 
		} else {
			throw new Exception("验证邮箱地址错误");
		}
	}