常见的模板引擎有JSP、Velocity、Freemarker、Thymeleaf
SpringBoot推荐使用Thymeleaf；

一、引入Thymeleaf启动器依赖、

<dependency>
            <groupId>org.thymeleaf</groupId>
            <artifactId>thymeleaf-spring5</artifactId>
        </dependency>

如需切换thymeleaf版本：

<properties>

        <thymeleaf.version>X.X.X.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>

二、Thymeleaf使用

这里直接看源码了
默认只要我们把HTML页面放在classpath:/templates/，thymeleaf就能自动渲染；

@ConfigurationProperties(prefix = "spring.thymeleaf")   //与配置文件相关联
public class ThymeleafProperties {

    private static final Charset DEFAULT_ENCODING = StandardCharsets.UTF_8;  //编码格式

    public static final String DEFAULT_PREFIX = "classpath:/templates/";  //默认的读取路径

    public static final String DEFAULT_SUFFIX = ".html";  //默认的后缀名

1、创建模板文件t1.html，并导入thymeleaf的名称空间

<html lang="en" xmlns:th="http://www.thymeleaf.org">

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
</html>

2、在controller中准备数据

@RequestMapping("thy")
    public String thy(Map<String,Object> map){
        map.put("til","thymelaf测试页面");
        map.put("ceshi","<h2  style='color: red'>utext会转义特殊字符，如：html标签</h2>");
        map.put("list", Arrays.asList("zhangshan","lisi","wangwu"));
        return "thymeleaf01";
    }

3、使用模板

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>[[${til}]]</title>
</head>
<body>
  <div th:text="${til}">这是一个页面</div>
<div th:utext="${ceshi}"></div>
 <hr/>
  <h2 th:each="item : ${list}">[[${item}]]</h2>
</body>
</html>

三、语法规则

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

image.png

2、语法表达式

Simple expressions:（表达式语法）
    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).

    Selection Variable Expressions: *{...}：选择表达式：和${}在功能上是一样；
        补充：配合 th:object="${session.user}：
   <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>
    
    Message Expressions: #{...}：获取国际化内容
    Link URL Expressions: @{...}：定义URL；
            @{/order/process(execId=${execId},execType='FAST')}
    Fragment Expressions: ~{...}：片段引用表达式
            <div th:insert="~{commons :: main}">...</div>
            
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 ,…
Text operations:（文本操作）
    String concatenation: +
    Literal substitutions: |The name is ${name}|
Arithmetic operations:（数学运算）
    Binary operators: + , - , * , / , %
    Minus sign (unary operator): -
Boolean operations:（布尔运算）
    Binary operators: and , or
    Boolean negation (unary operator): ! , not
Comparisons and equality:（比较运算）
    Comparators: > , < , >= , <= ( gt , lt , ge , le )
    Equality operators: == , != ( eq , ne )
Conditional operators:条件运算（三元运算符）
    If-then: (if) ? (then)
    If-then-else: (if) ? (then) : (else)
    Default: (value) ?: (defaultvalue)
Special tokens:
    No-Operation: _

更多配置参考官方文档：https://www.thymeleaf.org/documentation.html

SpringBoot - thymeleaf模板引擎(七)

SpringBoot - thymeleaf模板引擎(七)

一、引入Thymeleaf启动器依赖、

二、Thymeleaf使用

1、创建模板文件t1.html，并导入thymeleaf的名称空间

2、在controller中准备数据

3、使用模板

三、语法规则

更多配置参考官方文档：https://www.thymeleaf.org/documentation.html