If you have a POJO with a property like below:

@Column(length = 4, nullable = false)
public String getInitials() {
return initials;
}

Then the generated input tag should limit data entry to the length set in the POJO. See Struts 2 example below:

    <s:textfield key="person.initials" required="true" maxlength="4" cssClass="text medium"/>