（四）Thymeleaf标准表达式之——[3->6] 操作符（文本、算术、布尔、比较及相等）

2.3 文本操作符

模板名称：text.html
连接符： + 可以是任意字符和表达式等
文本替换符：| 不能表达出条件表达式(官网：只能是变量表达式)
e.g.

1.<span th:text="|Welcome to our application, ${user.name}!|">
2.<span th:text="'Welcome to our application, ' + ${user.name} + '!'">
3.<span th:text="${onevar} + ' ' + |${twovar}, ${threevar}|">

2.4 算术运算符
模板名称：operator.html
+, -, *, /, %
e.g.

<ol>
<li>+：<span th:text="1+1">1+1</span>.</li>
<li>-： <span th:text="2-1">2-1</span>.</li>
<li>*：<span th:text="2*3">2*3</span>.</li>
<li>/： <span th:text="9/4">9/4</span>.</li>
<li>%：<span th:text="9%4">9%4</span>.</li>
</ol>

2.5 布尔运算
模板名称：operator-boolean.html
1 二元运算：and, or
2 布尔否定（一元运算符）：!, not
e.g.

<ol>
<li>
and：<span  th:if="${!#lists.isEmpty(list)} and ${#lists.isEmpty(list)}" th:text="${!#lists.isEmpty(list)} and ${#lists.isEmpty(list)}">and</span>
</li>

<li>
or：<span  th:if="${!#lists.isEmpty(list)} or ${#lists.isEmpty(list)}" th:text="${!#lists.isEmpty(list)} or ${#lists.isEmpty(list)}">or</span>
</li>

<li>!(not)：<span  th:if="${!#lists.isEmpty(list)}" th:text="${!#lists.isEmpty(list)}">not</span></li>
</ol>

2.6.比较和相等运算符
模板名称：operator-equal.html
1 比较运算：>, <, >=, <=
2 相等运算：==, !=
e.g.

<ol>
<li>>(gt)：<span th:text="1+1" th:if="${#lists.size(list)} > 1">大于></span>else</li>
<li>小于lt：<span th:if="${#lists.size(list)} lt 1">小于</span>else</li>
<li>>=(ge)：<span  th:if="${#lists.size(list)} >= 1">大于等于>=</span>else</li>
<li>小于等于(le)：<span  th:if="${#lists.size(list)} le 1">小于等于</span>else</li>
<li>!(not)：<span  th:if="${!#lists.isEmpty(list)}">!(not)</span>else</li>
<li>==(eq)：<span th:text="'Execution mode is ' + ( (${execMode} == 'dev')? 'Development' : 'Production')">等于==</span></li>
<li>!=(ne/neq)：size:<span th:text="${#lists.size(list)}" th:if="${#lists.size(list)} != 1"></span></li>
</ol>