springboot學習之Thymeleaf模板引擎及原理介紹

模板引擎

springboot我們目前是以jar包的形式打包,實際上我們之前是打成war包,放到tomcat服務器裡面,可以用JSP。
但是jar包就導致不能用JSP,換一種方式就是springboot推薦的Thymeleaf模板引擎(JSP也是一種模板引擎,除此之外還有什麼framework也是一種模板引擎),

什麼是模板引擎?

模板引擎就是解決我們需要動態賦值給前端的一種解決方案
(模板引擎的作用就是我們來寫一個頁面模板,比如有些值呢,是動態的,我們寫一些表達式。而這些值,從哪來呢,就是我們在後臺封裝一些數據。然後把這個模板和這個數據交給我們模板引擎,模板引擎按照我們這個數據幫你把這表達式解析、填充到我們指定的位置,然後把這個數據最終生成一個我們想要的內容給我們寫出去,這就是我們這個模板引擎,不管是jsp還是其他模板引擎,都是這個思想。隻不過呢,就是說不同模板引擎之間,他們可能這個語法有點不一樣。其他的我就不介紹瞭,我主要來介紹一下SpringBoot給我們推薦的Thymeleaf模板引擎,這模板引擎呢,是一個高級語言的模板引擎,他的這個語法更簡單。而且呢,功能更強大。)

模板引擎的原理

引入Thymeleaf

引入就是導入依賴,以下是網址是相關的地址
Thymeleaf 官網:https://www.thymeleaf.org/

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

Spring官方文檔:找到我們對應的版本

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

找到對應的pom依賴:可以適當點進源碼看下本來的包!

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

Thymeleaf分析

Thymeleaf的引入依賴文件ThymeleafProperties,文件內容如下:

  // 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 */ }
    public 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<org.springframework.http.MediaType> mediaTypes;
        private java.lang.String[] fullModeViewNames;
        private java.lang.String[] chunkedModeViewNames;
        public Reactive() { /* compiled code */ }
        public java.util.List<org.springframework.http.MediaType> getMediaTypes() { /* compiled code */ }
        public void setMediaTypes(java.util.List<org.springframework.http.MediaType> 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 */ }
}

我們可以在其中看到默認的前綴和後綴。
我們隻需要把我們的html頁面放在類路徑下的templates下,thymeleaf就可以幫我們自動渲染瞭。

啟動訪問結果

Thymeleaf 語法學習

要學習語法,還是參考官網文檔最為準確,我們找到對應的版本看一下;

Thymeleaf 官網:https://www.thymeleaf.org/ , 簡單看一下官網!我們去下載Thymeleaf的官方文檔!

做一個最簡單的向頁面傳值操作
(1)寫一個頁面,一個msg來作為傳值

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>ZP</title>
</head>
<body>
<h1>測試頁面</h1>

<!--th:text就是將div中的內容設置為它指定的值,和之前學習的Vue一樣-->
<div th:text="${msg}"></div>
</body>
</html>

代碼
註意這裡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){
        //存入數據
        model.addAttribute("msg","Hello,Thymeleaf");
        //classpath:/templates/test.html
        return "text2";
    }
}

測試

通過thymeleaf官網文檔學習一些語法:
1、我們可以使用任意的 th:attr 來替換Html中原生屬性的值!

2、我們能寫哪些表達式呢?

Simple expressions:(表達式語法)
Variable Expressions: ${...}:獲取變量值;OGNL;
    1)、獲取對象的屬性、調用方法
    2)、使用內置的基本對象:#18
         #ctx : the context object.
         #vars: the context variables.
         #locale : the context locale.
         #request : (only in Web Contexts) the HttpServletRequest object.
         #response : (only in Web Contexts) the HttpServletResponse object.
         #session : (only in Web Contexts) the HttpSession object.
         #servletContext : (only in Web Contexts) the ServletContext object.
    3)、內置的一些工具對象:
      #execInfo : information about the template being processed.
      #uris : methods for escaping parts of URLs/URIs
      #conversions : methods for executing the configured conversion service (if any).
      #dates : methods for java.util.Date objects: formatting, component extraction, etc.
      #calendars : analogous to #dates , but for java.util.Calendar objects.
      #numbers : methods for formatting numeric objects.
      #strings : methods for String objects: contains, startsWith, prepending/appending, etc.
      #objects : methods for objects in general.
      #bools : methods for boolean evaluation.
      #arrays : methods for arrays.
      #lists : methods for lists.
      #sets : methods for sets.
      #maps : methods for maps.
      #aggregates : methods for creating aggregates on arrays or collections.
==================================================================================
  Selection Variable Expressions: *{...}:選擇表達式:和${}在功能上是一樣;
  Message Expressions: #{...}:獲取國際化內容
  Link URL Expressions: @{...}:定義URL;
  Fragment Expressions: ~{...}:片段引用表達式
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:(數學運算)
    Binary operators: + , - , * , / , %
    Minus sign (unary operator): -
Boolean operations:(佈爾運算)
    Binary operators: and , or
    Boolean negation (unary operator): ! , not
Comparisons and equality:(比較運算)
    Comparators: > , < , >= , <= ( gt , lt , ge , le )
    Equality operators: == , != ( eq , ne )
Conditional operators:條件運算(三元運算符)
    If-then: (if) ? (then)
    If-then-else: (if) ? (then) : (else)
    Default: (value) ?: (defaultvalue)
Special tokens:
    No-Operation: _

練習測試:

1、 我們編寫一個Controller,放一些數據

 @RequestMapping("/t2")
    public String test2(Map<String,Object> map){
        //存入數據
        map.put("msg","<h1>Hello</h1>");
        map.put("users", Arrays.asList("zp","zhangpeng"));
        //classpath:/templates/test.html
        return "text3";
    }
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>狂神說</title>
</head>
<body>
<h1>測試頁面</h1>
<div th:text="${msg}"></div>
<!--不轉義-->
<div th:utext="${msg}"></div>
<!--遍歷數據-->
<!--th:each每次遍歷都會生成當前這個標簽:官網#9-->
<h4 th:each="user :${users}" th:text="${user}"></h4>
<h4>
    <!--行內寫法:官網#12-->
    <span th:each="user:${users}">[[${user}]]</span>
</h4>
</body>
</html>

到此這篇關於springboot學習Thymeleaf模板引擎的文章就介紹到這瞭,更多相關springboot Thymeleaf模板引擎內容請搜索WalkonNet以前的文章或繼續瀏覽下面的相關文章希望大傢以後多多支持WalkonNet!

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