footer.html

<div th:fragment="common">
    <select class="selectpicker">
        <option>Mustard</option>
        <option>Ketchup</option>
        <option>Barbecue</option>
    </select>
</div>

//直接加载
<th:block th:include="footer :: common" />
//放到div 里
<div th:include="footer :: common"></div>

//footer为路径，以resources/templates/为根目录

如文件放在 resources/templates/abc/footer.html

<th:block th:include="/abc/footer :: common" />

common为th:fragment="common"的common，表示加载这里面的内容

//传值写法 select 的nane 传source
<th:block th:include="labelThymeleaf :: common('source')" />


//用户th:name="${name}"赋值
<div th:fragment="common(name)">
    <select th:name="${name}" class="selectpicker">
        <option>Mustard</option>
        <option>Ketchup</option>
        <option>Barbecue</option>
    </select>
</div>

//正式环境可能报路径错误
将<th:block th:include="labelThymeleaf :: common('source')" /> 
写法，改成元素包裹 路径区分大小写并且首行无/
<span th:include="IpManagement/labelThymeleaf :: commonSource('source')" />