springboot Thymeleaf

模板引擎

模板引擎作用：根据页面模板和数据生成展示页面

初识Thymeleaf

引入Thymeleaf

Thymeleaf 官网：https://www.thymeleaf.org/

Thymeleaf 在Github 的主页：https://github.com/thymeleaf/thymeleaf

Spring官方文档：https://docs.spring.io/spring-boot/docs/2.2.5.RELEASE/reference/htmlsingle/#using-boot-starter

        <dependency>
            <groupId>org.thymeleaf</groupId>
            <artifactId>thymeleaf-spring5</artifactId>
        </dependency>
        <dependency>
            <groupId>org.thymeleaf.extras</groupId>
            <artifactId>thymeleaf-extras-java8time</artifactId>
        </dependency>

编写模板

1、模板位置（两次敲击Shift）

@ConfigurationProperties(prefix = "spring.thymeleaf")
public class ThymeleafProperties {

    private static final Charset DEFAULT_ENCODING = StandardCharsets.UTF_8;

    public static final String DEFAULT_PREFIX = "classpath:/templates/";

    public static final String DEFAULT_SUFFIX = ".html";

2、thymeleaf应用

https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#using-texts

添加thymeleaf约束（xmlns:th="http://www.thymeleaf.org"）,方便提示

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

编写Controller

@Controller
public class TestController {

    @GetMapping("/test")
    public String test(Model model){
        model.addAttribute("msg","Hello Thymeleaf");
        return "test";
    }
}

Thymeleaf 语法学习

表达式：https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#standard-expression-syntax

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：#18
         #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）、内置的一些工具对象：
　　　　　　#execInfo : information about the template being processed.
　　　　　　#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.
==================================================================================

  Selection Variable Expressions: *{...}：选择表达式：和${}在功能上是一样；
  Message Expressions: #{...}：获取国际化内容
  Link URL Expressions: @{...}：定义URL；
  Fragment Expressions: ~{...}：片段引用表达式

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: _

属性设置：https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#attribute-precedence

Order	特征	Attributes	备注
1	Fragment inclusion	`th:insert` `th:replace`	`片段包含：相当于include`
2	Fragment iteration	`th:each`	`循环`
3	Conditional evaluation	`th:if` `th:unless` `th:switch` `th:case`	`判断`
4	Local variable definition	`th:object` `th:with`
5	General attribute modification	`th:attr` `th:attrprepend` `th:attrappend`	`通用属性修改`
6	Specific attribute modification	`th:value` `th:href` `th:src` `...`	`th:可以修饰Html的标签属性`
7	Text (tag body modification)	`th:text` `th:utext`	`转义特殊字符` 不转义特殊字符
8	Fragment specification	`th:fragment`	`声明片段`
9	Fragment removal	`th:remove`

练习测试

1、Controller

    @RequestMapping("/t2")
    public String test2(Map<String,Object> map){
        //存入数据
        map.put("msg","<h1>Hello</h1>");
        map.put("users", Arrays.asList("xiaoqiang","dahuang"));
        //classpath:/templates/test.html
        return "test";
    }

2、html

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

<!--不转义-->
<div th:utext="${msg}"></div>

<!--遍历数据-->
<!--th:each每次遍历都会生成当前这个标签：官网#9-->
<h4 th:each="user :${users}" th:text="${user}"></h4>

<h4>
    <!--行内写法：官网#12-->
    <span th:each="user:${users}">[[${user}]]</span>
</h4>
</body>
</html>