springboot学习之Thymeleaf模板引擎及原理介绍

网友投稿 281 2022-08-25


springboot学习之Thymeleaf模板引擎及原理介绍

目录模板引擎什么是模板引擎?模板引擎的原理引入ThymeleafThymeleaf分析Thymeleaf语法学习

模板引擎

springboot我们目前是以jar包的形式打包,实际上我们之前是打成war包,放到tomcat服务器里面,可以用jsP。但是jar包就导致不能用JSP,换一种方式就是springboot推荐的Thymeleaf模板引擎(JSP也是一种模板引擎,除此之外还有什么framework也是一种模板引擎),

什么是模板引擎?

模板引擎就是解决我们需要动态赋值给前端的一种解决方案(模板引擎的作用就是我们来写一个页面模板,比如有些值呢,是动态的,我们写一些表达式。而这些值,从哪来呢,就是我们在后台封装一些数据。然后把这个模板和这个数据交给我们模板引擎,模板引擎按照我们这个数据帮你把这表达式解析、填充到我们指定的位置,然后把这个数据最终生成一个我们想要的内容给我们写出去,这就是我们这个模板引擎,不管是jsp还是其他模板引擎,都是这个思想。只不过呢,就是说不同模板引擎之间,他们可能这个语法有点不一样。其他的我就不介绍了,我主要来介绍一下SpringBoot给我们推荐的Thymeleaf模板引擎,这模板引擎呢,是一个高级语言的模板引擎,他的这个语法更简单。而且呢,功能更强大。)

模板引擎的原理

引入Thymeleaf

引入就是导入依赖,以下是网址是相关的地址Thymeleaf 官网:https://thymeleaf.org/

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

Spring官方文档:找到我们对应的版本

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

找到对应的pom依赖:可以适当点进源码看下本来的包!

org.springframework.boot

spring-boot-starter-thymeleaf

Thymeleaf分析

Thymeleaf的引入依赖文件ThymeleafProperties,文件内容如下:

// IntelliJ API Decompiler stub source generated from a class file

// Implementation of methods is not available

package org.springframework.boot.autoconfigure.thymeleaf;

@org.springframework.boot.context.properties.ConfigurationProperties(prefix = "spring.thymeleaf")

public class ThymeleafProperties {

private static final java.nio.charset.Charset DEFAULT_ENCODING;

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

public static final java.lang.String DEFAULT_SUFFIX = ".html";

private boolean checkTemplate;

private boolean checkTemplateLocation;

private java.lang.String prefix;

private java.lang.String suffix;

private java.lang.String mode;

private java.nio.charset.Charset encoding;

private boolean cache;

private java.lang.Integer templateResolverOrder;

private java.lang.String[] viewNames;

private java.lang.String[] excludedViewNames;

private boolean enableSpringElCompiler;

private boolean renderHiddenMarkersBeforeCheckboxes;

private boolean enabled;

private final org.springframework.boot.autoconfigure.thymeleaf.ThymeleafProperties.Servlet servlet;

private final org.springframework.boot.autoconfigure.thymeleaf.ThymeleafProperties.Reactive reactive;

public ThymeleafProperties() { /* compiled code */ }

public boolean isEnabled() { /* compiled code */ }

public void setEnabled(boolean enabled) { /* compiled code */ }

public boolean isCheckTemplate() { /* compiled code */ }

public void setCheckTemplate(boolean checkTemplate) { /* compiled code */ }

public boolean isCheckTemplateLocation() { /* compiled code */ }

public void setCheckTemplateLocation(boolean checkTemplateLocation) { /* compiled code */ }

publcoTkAvUic java.lang.String getPrefix() { /* compiled code */ }

public void setPrefix(java.lang.String prefix) { /* compiled code */ }

public java.lang.String getSuffix() { /* compiled code */ }

public void setSuffix(java.lang.String suffix) { /* compiled code */ }

public java.lang.String getMode() { /* compiled code */ }

public void setMode(java.lang.String mode) { /* compiled code */ }

public java.nio.charset.Charset getEncoding() { /* compiled code */ }

public void setEncoding(java.nio.charset.Charset encoding) { /* compiled code */ }

public boolean isCache() { /* compiled code */ }

public void setCache(boolean cache) { /* compiled code */ }

public java.lang.Integer getTemplateResolverOrder() { /* compiled code */ }

public void setTemplateResolverOrder(java.lang.Integer templateResolverOrder) { /* compiled code */ }

public java.lang.String[] getExcludedViewNames() { /* compiled code */ }

public void setExcludedViewNames(java.lang.String[] excludedViewNames) { /* compiled code */ }

public java.lang.String[] getViewNames() { /* compiled code */ }

public void setViewNames(java.lang.String[] viewNames) { /* compiled code */ }

public boolean isEnableSpringElCompiler() { /* compiled code */ }

public void setEnableSpringElCompiler(boolean enableSpringElCompiler) { /* compiled code */ }

public boolean isRenderHiddenMarkersBeforeCheckboxes() { /* compiled code */ }

public void setRenderHiddenMarkersBeforeCheckboxes(boolean renderHiddenMarkersBeforeCheckboxes) { /* compiled code */ }

public org.springframework.boot.autoconfigure.thymeleaf.ThymeleafProperties.Reactive getReactive() { /* compiled code */ }

public org.springframework.boot.autoconfigure.thymeleaf.ThymeleafProperties.Servlet getServlet() { /* compiled code */ }

public static class Reactive {

private org.springframework.util.unit.DataSize maxChunkSize;

private java.util.List mediaTypes;

private java.lang.String[] fullModeViewNames;

private java.lang.String[] chunkedModeViewNames;

public Reactive() { /* compiled code */ }

public java.util.List getMediaTypes() { /* compiled code */ }

public void setMediaTypes(java.util.List mediaTypes) { /* compiled code */ }

public org.springframework.util.unit.DataSize getMaxChunkSize() { /* compiled code */ }

public void setMaxChunkSize(org.springframework.util.unit.DataSize maxChunkSize) { /* compiled code */ }

public java.lang.String[] getFullModeViewNames() { /* compiled code */ }

public void setFullModeViewNames(java.lang.String[] fullModeViewNames) { /* compiled code */ }

public java.lang.String[] getChunkedModeViewNames() { /* compiled code */ }

public void setChunkedModeViewNames(java.lang.String[] chunkedModeViewNames) { /* compiled code */ }

}

public static class Servlet {

private org.springframework.util.MimeType contentType;

private boolean producePartialOutputWhileProcessing;

public Servlet() { /* compiled code */ }

public org.springframework.util.MimeType getContentType() { /* compiled code */ }

public void setContentType(org.springframework.util.MimeType contentType) { /* compiled code */ }

public boolean isProducePartialOutputWhileProcessing() { /* compiled code */ }

public void setProducePartialOutputWhileProcessing(boolean producePartialOutputWhileProcessing) { /* compiled code */ }

}

我们可以在其中看到默认的前缀和后缀。我们只需要把我们的html页面放在类路径下的templates下,thymeleaf就可以帮我们自动渲染了。

启动访问结果

Thymeleaf 语法学习

要学习语法,还是参考官网文档最为准确,我们找到对应的版本看一下;

Thymeleaf 官网:https://thymeleaf.org/ , 简单看一下官网!我们去下载Thymeleaf的官方文档!

做一个最简单的向页面传值操作(1)写一个页面,一个msg来作为传值

代码注意这里return的字符串要和上面的templates下面的html文件名字相同。

package com.example.zpspringboot3.controller;

import org.springframework.stereotype.Controller;

import org.springframework.ui.Model;

import org.springframework.web.bind.annotation.RequestMapping;

/**

* @Author: zhangpeng

* @Date: 2022/2/21 16:02

*/

@Controller

public class TestController {

// @RequestMapping("/t1")

// public String test1(){

// //classpath:/templates/test.html

// return "text";

// }

@RequestMapping("/t1")

public String test1(Model model){

//存入数据

model.addAttribute("msg","Hello,Thymeleaf");

//classpath:/templates/test.html

return "text2";

}

}

测试

通过thymeleaf官网文档学习一些语法:1、我们可以使用任意的 th:attr 来替换Html中原生属性的值!

2、我们能写哪些表达式呢?

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.

#sessiohttp://n : (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: _

练习测试:

1、 我们编写一个Controller,放一些数据

@RequestMapping("/t2")

public String test2(Map map){

//存入数据

map.put("msg","

map.put("users", Arrays.asList("zp","zhangpeng"));

//classpath:/templates/test.html

return "text3";

}

[[${user}]]


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