参考说明：以下笔记参考来自尚硅谷springboot教学中的笔记！
thymeleaf官网docs： https://www.thymeleaf.org/documentation.html
模板引擎：
JSP、Velocity、Freemarker、Thymeleaf
语法更简单，功能更强大；
1、引入thymeleaf：
<dependency> <groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId> 2.1.6 </dependency>
切换thymeleaf版本 <properties> <thymeleaf.version>3.0.9.RELEASE</thymeleaf.version> <!-- 布局功能的支持程序 thymeleaf3主程序 layout2以上版本 --> <!-- thymeleaf2 layout1--> <thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version> </properties>
@ConfigurationProperties(prefix = "spring.thymeleaf") public class ThymeleafProperties { private static final Charset DEFAULT_ENCODING = Charset.forName("UTF-8"); private static final MimeType DEFAULT_CONTENT_TYPE = MimeType.valueOf("text/html"); public static final String DEFAULT_PREFIX = "classpath:/templates/"; public static final String DEFAULT_SUFFIX = ".html"; //
以上是package org.springframework.boot.autoconfigure.thymeleaf;包中的源码，放在这里主要是告诉你模块该如何配置;
只要我们把HTML页面放在classpath:/templates/，thymeleaf就能自动渲染；
(1) 导入thymeleaf的名称空间（导入后有语法提示）
<html lang="en" xmlns:th="http://www.thymeleaf.org">
(2) 使用thymeleaf语法:
<!DOCTYPE html> <html lang="en" xmlns:th="http://www.thymeleaf.org"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <h1>成功！</h1> <!--th:text 将div里面的文本内容设置为 --> <div th:text="${hello}">这是显示欢迎信息</div> </body> </html>
1）、th:text；改变当前元素里面的文本内容；
th：任意html属性；来替换原生属性的值（eg: th:id=1改变id的值, th:class=“c1”改变class的值）
补充：
<div th:remove="tag">
<div>唐嫣</div> //包含标记的标签将被删除，即这里的外层div将被删除 参考：th:remove用法
</div>
2）、表达式？
1、Simple expressions:（表达式语法） (1)Variable Expressions: ${...}：获取变量值；OGNL； 1）、获取对象的属性、调用方法 2）、使用内置的基本对象： #ctx : the context object. #vars: the context variables. #locale : the context locale. #request : (only in Web Contexts) the HttpServletRequest object. #response : (only in Web Contexts) the HttpServletResponse object. #session : (only in Web Contexts) the HttpSession object. #servletContext : (only in Web Contexts) the ServletContext object. ${session.foo} 3）、内置的一些工具对象： #execInfo : information about the template being processed. #messages : methods for obtaining externalized messages inside variables expressions, in the same way as they would be obtained using #{…} syntax. #uris : methods for escaping parts of URLs/URIs #conversions : methods for executing the configured conversion service (if any). #dates : methods for java.util.Date objects: formatting, component extraction, etc. #calendars : analogous to #dates , but for java.util.Calendar objects. #numbers : methods for formatting numeric objects. #strings : methods for String objects: contains, startsWith, prepending/appending, etc. #objects : methods for objects in general. #bools : methods for boolean evaluation. #arrays : methods for arrays. #lists : methods for lists. #sets : methods for sets. #maps : methods for maps. #aggregates : methods for creating aggregates on arrays or collections. #ids : methods for dealing with id attributes that might be repeated (for example, as a result of an iteration). (2)Selection Variable Expressions: *{...}：选择表达式：和${}在功能上是一样； 补充：配合 th:object="${session.user}：#只有作为全局变量使用的时候才是不一样的 eg: 用th:object从session里面取出user对象(即将取出来的对象赋值给Object)，以后要用user对象的值，就可以在当前的div里面，
"*"号就代表刚才的th:object对象，然后直接获取对象的属性即可。
<div th:object="${session.user}"> <p>Name: <span th:text="*{firstName}">Sebastian</span>.</p> <p>Surname: <span th:text="*{lastName}">Pepper</span>.</p> <p>Nationality: <span th:text="*{nationality}">Saturn</span>.</p> </div>
--以上方式等于如下方式$和*号功能是一样的，而且$和*可以混合使用
<div th:object="${session.user}">
<p>Name: <span th:text="*{firstName}">Sebastian</span>.</p>
<p>Surname: <span th:text="${session.user.lastName}">Pepper</span>.</p>
<p>Nationality: <span th:text="*{nationality}">Saturn</span>.</p>
</div> (3)Message Expressions: #{...}：获取国际化内容 (4)Link URL Expressions: @{...}：定义URL； @{/order/process(execId=${execId},execType='FAST')} (5)Fragment Expressions: ~{...}：片段引用表达式 <div th:insert="~{commons :: main}">...</div> 2、Literals（字面量） Text literals: 'one text' , 'Another one!' ,… Number literals: 0 , 34 , 3.0 , 12.3 ,… Boolean literals: true , false Null literal: null Literal tokens: one , sometext , main ,… 3、Text operations:（文本操作） String concatenation: + Literal substitutions: |The name is ${name}| 4、Arithmetic operations:（数学运算） Binary operators: + , - , * , / , % Minus sign (unary operator): - 5、Boolean operations:（布尔运算） Binary operators: and , or Boolean negation (unary operator): ! , not 6、Comparisons and equality:（比较运算） Comparators: > , < , >= , <= ( gt , lt , ge , le ) Equality operators: == , != ( eq , ne ) 7、Conditional operators:条件运算（三元运算符） If-then: (if) ? (then) If-then-else: (if) ? (then) : (else) Default: (value) ?: (defaultvalue) 8、Special tokens(特殊操作): No-Operation: _
9、内联表达式
<p>Hello, [[${session.user.name}]]!</p>
任何在th:text或th:utext属性中使⽤的表达式都可以出现在[[]]或[()]中.
[[...]]等价于th:text（即结果将被HTML转义） ， [(...)]等价于th:utext， 不会执⾏任何HTML转义