validator for characters exceeding size of a text box

I have a table one of whose column is varchar(64). I am building a web form in Java using JSF where the form has a text box where the users type in free text and is saved to the column in the above mentioned table. I need to write a validator to check if the number of characters in the text box exceeds 64 (as it w开发者_开发技巧ill crash when saved to the database). Need some suggestions to write this validator.

You can do something like this

<h:inputText id="username" value="#{user.username}" 
                size="64" required="true"
                label="UserName" >
                <f:validateLength minimum="0" maximum="64" />
            </h:inputText>  

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