List EL expression how to determine the length of the list

1, the introduction of the corresponding tag library

<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions"%> 

2, is determined in an EL expression

<c:if test="${tzfcgtjbmxx != null && fn:length(tzfcgtjbmxx) < 3 }">
    <!-- 相关操作 -->
</c:if>