java根据身份证号码算出年龄

//根据身份证号输出年龄
public static int IdNOToAge(String IdNO){
int leh = IdNO.length();
String dates="";
if (leh == 18) {
int se = Integer.valueOf(IdNO.substring(leh - 1)) % 2;
dates = IdNO.substring(6, 10);
SimpleDateFormat df = new SimpleDateFormat("yyyy");
String year=df.format(new Date());
int u=Integer.parseInt(year)-Integer.parseInt(dates);
return u;
}else{
dates = IdNO.substring(6, 8);
return Integer.parseInt(dates);
}

}

public static void main(String[] args) {
IdNOToAge("320623199305150021"); //320621198804303
}