判断

if

<a href="comments.html" th:href="@{/product/comments(prodId=${prod.id})}" th:if="${not #lists.isEmpty(prod.comments)}">view</a>

unless

<a href="comments.html" th:href="@{/comments(prodId=${prod.id})}" th:unless="${#lists.isEmpty(prod.comments)}">view</a>

switch

<div th:switch="${user.role}">
    <p th:case="'admin'">User is an administrator</p> <p th:case="#{roles.manager}">User is a manager</p>
</div>

<div th:switch="${user.role}">
    <p th:case="'admin'">User is an administrator</p> <p th:case="#{roles.manager}">User is a manager</p> <p th:case="*">User is some other thing</p>
</div>