用户验证(simple)
public void validate()
{
System.out.println("validate~~~~~~~~~~~~~~~~~~~~~~");
if(null == username || username.length() < 6 || username.length() > 10)
{

this.addFieldError("username", "username invalid");

}
if(null == password || password.length()<6 || password.length() < 10 )
{

this.addFieldError("password", "password invalid");

}
else if(null == repassword || repassword.length() < 6 || repassword.length() >10)
{

this.addFieldError("repassword", "re-password invalid");

}
else if(!password.equals(repassword))
{
this.addFieldError("password", "two password not the same");

}
if(age < 1 || age >150)
{
this.addFieldError("age", "age invalid");

}
if(null == birthday)
{
this.addFieldError("birthday", "birthday invalid");

}
if(null == graduation)
{
this.addFieldError("graduation", "graduation invalid");

}
if(null != birthday && null !=graduation )
{
Calendar c1 = Calendar.getInstance();
c1.setTime(birthday);

Calendar c2 = Calendar.getInstance();
c2.setTime(graduation);

if(!c1.before(c2))
{
this.addFieldError("birthday", "birthday should be before graduation");

}
}

}