code: public static String getIpByHost(String hostName) {
  		try {
  			return InetAddress.getByName(hostName).getHostAddress();
  		} catch (UnknownHostException e) {
  			return hostName;
  		}
  	}
docs: 通过域名得到IP
  
  @param hostName HOST
  @return ip address or hostName if UnknownHostException