模板引擎

SpringBoot之模板引擎Thymeleaf的使用

SpringBoot不推荐使用JSP。

常见的模板引擎有:
JSP
Velocity
Thymeleaf
Freemarker

模板引擎的核心
模板引擎_第1张图片

SpringBoot推荐使用thymeleaf,引入依赖


<dependency>
    <groupId>org.springframework.bootgroupId>
    <artifactId>spring-boot-starter-thymeleafartifactId>
dependency>

如果想要引入3.x版本 ,需要再做设置

<properties>
    
    <thymeleaf.version>3.0.2.RELEASEthymeleaf.version>
    
    <thymeleaf-layout-dialect.version>2.1.1thymeleaf-layout-dialect.version>
    properties>

在源码中可以看到:

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";
    private boolean checkTemplate = true;
    private boolean checkTemplateLocation = true;
    private String prefix = "classpath:/templates/";
    private String suffix = ".html";
    private String mode = "HTML5";
    private Charset encoding;
    //只需要将html放到classpath:templetas/,thymeleaf就能自动渲染

实例:

@RequestMapping("/index")
    public String thymeleafTest(){
        return "hello thymeleaf";
    }

在resources目录下新建index.html,运行项目就能看到index.html的内容了。

在SpringBoot中如何使用thymeleaf



<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Titletitle>
head>
<body>
    <h1>Helloh1>
    
    <div th:text="${name}">这是欢迎页面显示的内容div>
body>
html>

如果想要看到controller方法返回的是页面而不是方法的返回值,注意不要再controller类上添加@RestController 而是添加@Controller

关于Thymeleaf的语法规则

  • th:text 改变当前元素里面的文本内容

模板引擎_第2张图片

表达式

Simple expressions:

  • 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
    
内置对象如下:
#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.
  • Selection Variable Expressions: *{…}
  • Message Expressions: #{…}
  • Link URL Expressions: @{…}
  • Fragment Expressions: ~{…}

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 ,…

Text operations:

  • String concatenation: +
  • Literal substitutions: |The name is ${name}|

Arithmetic operations:

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

Boolean operations:

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

Comparisons and equality:

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

Conditional operators:

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

Special tokens:

  • No-Operation: _

th:text和th:utext的区别:
th:text不会转义特殊字符,也就是说不会解析html标签,而th:utext反之

th:each作用的标签每次遍历都会产生新的标签

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