引入 thymeleaf

在 pom.xml 文件中输入以下内容引入 thymeleaf

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

若要切换 thymeleaf 版本，如 3.0.9，添加以下内容：

<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>

Thymeleaf 使用

只要把 HTML 页面放在 classpath:/templates/，thymeleaf 就能自动渲染；

在 templates 文件夹下创建 success.html，输 ！ 并回车生成代码，然后输入：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h1>成功</h1>
</body>
</html>

然后在 HelloController.java 中添加该页面的控制器：
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@RequestMapping("/success")
public String success() {
return "success"; // templates 中的文件
}
访问 localhost:8080/success 即可看到渲染的网页。

使用步骤：

导入thymeleaf的名称空间

在 success.html 文件中修改 <html> 标签：

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

使用thymeleaf语法

在 success.html 文件中修改 <body> 的内容：

<body>
    <h1>成功！</h1>
    <!--th:text 将div里面的文本内容设置为 -->
    <div th:text="${var}}">显示欢迎信息</div>
</body>

模板引擎会将变量 var 的值取出并显示。

语法规则

th:text改变当前元素里面的文本内容； th：任意html属性替换原生属性的值

表达式

获取变量值 Variable Expressions: ${...}

(1) 获取对象的属性、调用方法

(2) 使用内置的基本对象：

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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.

(3) 内置的工具对象：

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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).

选择表达式：和${}在功能上是一样 Selection Variable Expressions: *{...}

配合 th:object使用：

<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>

获取国际化内容 Message Expressions: #{...}

定义URL Link URL Expressions: @{...}

1	@{/order/process(execId=${execId},execType='FAST')}

片段引用表达式 Fragment Expressions: ~{...}
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<div th:insert="~{commons :: main}">...</div>

字面量 Literals:

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 ,…

文本操作 Text operations:

1 2	String concatenation: + Literal substitutions: \|The name is ${name}\|

数学运算 Arithmetic operations:

1 2	Binary operators: + , - , * , / , % Minus sign (unary operator): -

布尔运算 Boolean operations:

1 2	Binary operators: and , or Boolean negation (unary operator): ! , not

比较运算 Comparisons and equality:

1 2	Comparators: > , < , >= , <= ( gt , lt , ge , le ) Equality operators: == , != ( eq , ne )

条件运算(三元运算符) Conditional operators:

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If-then: (if) ? (then)
If-then-else: (if) ? (then) : (else)
Default: (value) ?: (defaultvalue)

Special tokens:
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No-Operation: _

实例演示：

修改 HelloController.java 的 success 控制器：

@RequestMapping("/success")
public String success(Map<String, Object> map) {
    map.put("hello", "<h1>你好</h1>");
    map.put("users", Arrays.asList("zhangsan", "lisi", "wangwu"));
    return "success";
}

修改 success.html 文件的 <body> 中的内容：

<body>
    <h1>成功</h1>
    <!--th:text 将div里面的文本内容设置为-->
    <div id="div01" class="myDiv" th:id="${hello}" th:class="${hello}" th:text="${hello}">
        显示欢迎信息
    </div>

    <hr/>
    <div th:text="${hello}"></div>
    <div th:utext="${hello}"></div>
    <hr/>

    <!-- th:each 每次遍历都会生成当前这个标签: 3 个 h4 -->
    <h4 th:text="${user}" th:each="user:${users}"></h4>
    <hr/>

    <h4>
        <span th:each="user:${users}"> [[${user}]]</span>
    </h4>
</body>