SpringBoot系列之集成Thymeleaf用法手冊

時間 2019-12-01

標籤 springboot 系列集成 thymeleaf 用法手冊欄目 Spring 简体版

原文原文鏈接

目錄javascript

SpringBoot系列之Thymeleaf語法簡單介紹css

@
Thymeleaf官方文檔已經有比較詳細的描述，因此本博客只挑部分比較重要的點看一下，還有介紹一下和SpringBoot怎麼集成使用html

一、模板引擎

引用百度百科的模板引擎解釋：前端

模板引擎（這裏特指用於Web開發的模板引擎）是爲了使用戶界面與業務數據（內容）分離而產生的，它能夠生成特定格式的文檔，用於網站的模板引擎就會生成一個標準的HTML文檔。html5

在JavaEE領域有幾中比較經常使用的模板引擎，分別是Jsp、Velocity、Freemarker、Thymeleaf，不過對於前端頁面渲染效率來講，jsp其實仍是最快的，Velocity次之。Thymeleaf雖然渲染效率不是很快，可是語法方面是比較輕巧的，Thymeleaf語法比Velocity輕巧，可是渲染效率不如Velocityjava

二、Thymeleaf簡介

2.1)、Thymeleaf定義

Thymeleaf是適用於Web和獨立環境的現代服務器端Java模板引擎，可以處理HTML，XML，JavaScript，CSS甚至純文本。具體參考Thymeleaf官網jquery

官網提供了在線文檔也有文件格式的各類文檔
git

2.2)、適用模板

Thymeleaf適用於以下模板：github

HTML
XML
TEXT
JAVASCRIPT
CSS
RAW

有兩種標記模板模式（HTML 和 XML）、三種文本模板模式（TEXT、JAVASCRIPT 和 CSS）和一種無操做模板模式（RAW）。web

ok，下面給出一些比較重要的知識點

三、重要知識點

3.1)、th:text和th:utext

這是很經常使用的text標籤，做用是Thymeleaf中設置文本的標籤，分爲兩種，一種是th:text，另一種是th:utext，兩種最重要的區別就是會不會對特殊字符進行轉義

th:text：將全部特殊字符轉成字符
th:utext：不會將特殊字符進行字符轉義

注意：這裏的特殊字符主要指html標籤，/n、/t、etc.這些字符是不支持的
寫個例子對比一下：

<span th:text="${'Welcome to our <b>fantastic</b> grocery store!'}"></span><br/>
<span th:utext="${'Welcome to our <b>fantastic</b> grocery store!'}"></span>

3.2)、標準表達式

官方文檔裏有standard Expression Syntax這個章節，介紹的就是標準的表達式語法應用

Simple expressions(簡單表達式語法):
- Variable Expressions: ${...} // 獲取遍歷值，支持OGNL語法 etc.
1. 獲取自定義對象的屬性值
2. 獲取自定義的變量屬性值
3. 使用內置的基本對象
  - 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.
  詳情參考Thymeleaf的附錄A
4. 內置的工具類對象
  官網已經給出比較詳細的介紹，詳細用法參考Thymeleaf附錄B
- Selection Variable Expressions: *{...} // 選定對象，也就是獲取使用 th：object 屬性的表達式的值
- Message Expressions: #{...} //國際化內容詳細用法參考個人博客：SpringBoot系列之i18n國際化多語言支持教程
- Link URL Expressions: @{...} // 定義URL連接

<link th:href="@{/static/css/public.css}" rel="stylesheet" type="text/css" />
    <link th:href="@{/static/css/index.css}" rel="stylesheet" type="text/css" />
    <script type="text/javascript" th:src="@{/static/js/jquery-1.3.2.min.js}"></script>
    <script type="text/javascript" th:src="@{/static/js/html5.js}"></script>
    <script type="text/javascript" th:src="@{/static/js/popbox.js}"></script>

* Fragment Expressions: ~{...} //片斷引用的表達式 eg: `<div th:insert="~{commons :: main}">....</div>`

Literals (字面量值)
- 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 (文本操做):
- String concatenation: + //鏈接操做 @{url/}+${id}
- Literal substitutions: |The name is ${name}| //字符串中使用${name}變量值
Arithmetic operations: (數學運算)
- Binary operators: +, -, *, /, %
- Minus sign (unary operator): -
Boolean operations:(布爾運算)
- 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，包括三元運算符etc.)
- If-then: (if) ? (then)
- If-then-else: (if) ? (then) : (else)
- Default: (value) ?: (defaultvalue)
Special tokens:(特殊的令牌，也就是使用No-Operatio)
- No-Operation: _
  
  All these features can be combined and neste:
  'User is of type ' + (${user.isAdmin()} ? 'Administrator' : (${user.type} ?: 'Unknown'))

翻譯過來意思是，這些語法均可以組合使用，這個章節是Thymeleaf一個重要的基本使用章節，本博客對一些重要的知識點進行摘錄同時介紹一下在SpringBoot裏如何使用，固然天然沒有官方文檔詳細的，不過官方並無經過中文文檔，英文水平很差的話，閱讀起來比較困難，固然我也找了一篇國內翻譯過來的Thymeleaf中文文檔，讀者詳細的能夠參考文檔

3.3)、Thymeleaf遍歷

遍歷是Thymeleaf很經常使用的例子，支持的屬性值有：

下面仍是給下例子，比較容易理解，以下代碼使用th:each，th:each="item : ${items}"

<!--最新上架-->
        <div class="first-pannel clearfix">
            <div class="index-f clearfix">
                <h3 class="index-f-head"> 最新上架 <span>天天都有上新，天天都有驚喜</span> </h3>
                <div class="index-f-body">
                    <div class="top-sales newProduct">
                        <ul class="top-sales-list clearfix">
                            <li class="top-sales-item newProduct" th:each="item : ${items}">
                                <p class="item-img"> <a th:href="@{'/portal/item/toDetail/'+${item.spuId}+'/'+${item.skuId}}"><img th:src="@{${item.imgPath}}" /></a> </p>
                                <p class="item-buss"><a th:href="@{'/portal/item/toDetail/'+${item.spuId}+'/'+${item.skuId}}"></a></p>
                                <p class="item-name spec"><a th:href="@{'/portal/item/toDetail/'+${item.spuId}+'/'+${item.skuId}}" th:text="${item.itemName}"></a></p>
                                <p class="item-price spec"><em th:text="${item.mPrice}"></em>元</p>
                            </li>
                        </ul>
                    </div>
                </div>
            </div>
        </div>
        <!--最新上架//-->

3.4)、公共模塊抽取

在項目開發中常常遇到一些能夠重用的頁面，這時候就能夠Thymeleaf的Template Layout進行公共頁面的複用

本博客以官方介紹的複用footer.html頁面進行說明

使用步驟：

抽取公共的片斷

<!DOCTYPE html>

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

  <body>
  
    <div th:fragment="copy">
      &copy; 2011 The Good Thymes Virtual Grocery
    </div>
  
  </body>
  
</html>

引入公共的片斷
<div th:insert="~{footer :: copy}"></div>
~{templatename::selector}：模板名::選擇器
~{templatename::fragmentname}:模板名::片斷名

<div th:insert="footer :: copy"></div>
<div th:replace="footer :: copy"></div>
<div th:include="footer :: copy"></div

三種引入公共片斷的th屬性：

th:insert：將公共片斷整個插入到聲明引入的元素中
th:replace：將聲明引入的元素替換爲公共片斷
th:include：將被引入的片斷的內容包含進這個標籤中

效果對比：

<div>
    <footer>
    &copy; 2011 The Good Thymes Virtual Grocery
    </footer>
</div>
<footer>
&copy; 2011 The Good Thymes Virtual Grocery
</footer>
<div>
&copy; 2011 The Good Thymes Virtual Grocery
</div

3.5)、行內寫法介紹

所謂行內寫法就是沒寫在html對應的標籤裏的寫法，直接在頁面空白處，用[[....]]或者[(....)]的寫法，而後[[....]]和[(....)]的區別其實就等同於th:text和th:utext的區別，一個會進行轉義，一個不會轉義特殊字符

[[....]]寫法：會轉義html標籤這些特殊字符(轉成字符)
[(....)]寫法：不會轉義html標籤這些特殊字符(按照其原意)
寫個例子就明白了：

<span>
    The message is [[${msg}]]
</span>
<br/>
<span>
    The message is [(${msg})]
</span>

3.6)、Thymeleaf語法規則

引用尚桂谷老師的概括：

四、SpringBoot集成

4.1)、Springboot集成Thymeleaf簡介

maven配置
由於引入了SpringBoot的parent工程，因此不須要寫版本號

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

application.yml配置
注意：這裏的屬性大部分均可以不配置的，由於Springboot的自動配置由於作了不少自動配置，咱們不配置，就使用默認的，不過下面的例子只是給讀者瞭解一下有這些配置

#添加Thymeleaf配置，除了cache在項目沒上線前建議關了，其它配置均可以不用配的，本博客只是列舉一下有這些配置
  thymeleaf:
    # cache默認開啓的，這裏能夠關了，項目上線以前，項目上線後能夠開啓
    cache: false
    # 這個prefix能夠註釋，由於默認就是templates的，您能夠改爲其它的自定義路徑
    prefix: classpath:/templates/
    suffix: .html
    mode: HTML5
    # 指定一下編碼爲utf8
    encoding: UTF-8
    # context-type爲text/html，也能夠不指定，由於boot能夠自動識別
    content-type: text/html

ok，Springboot中Thymeleaf使用很是簡單，由於Springboot已經爲咱們作了不少自動配置，其實，yaml都不須要配置的，直接引入對應的jar，而後就能夠直接使用，在resources資源文件夾下面新建一個templates文件夾，全部的html文件都丟在這裏，靜態資源文件也丟在resources資源文件夾下面

新建一個html文件，而後注意加上<html xmlns:th="http://www.thymeleaf.org">

注意Thymeleaf語法要求比較嚴格 <meta charset="utf-8" >，不如這樣寫是不能夠的，必須加上斜槓的，<meta charset="utf-8" />

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

<div>
    <span th:text="${'Welcome to our <b>fantastic</b> grocery store!'}"></span><br/>
    <span th:utext="${'Welcome to our <b>fantastic</b> grocery store!'}"></span>
</div>


<span>
    The message is [[${msg}]]
</span>
<br/>
<span>
    The message is [(${msg})]
</span>
</body>
</html>

4.2)、Thymeleaf自動配置源碼簡單分析

ok，而後爲何我說直接引入對應pom配置就能夠直接使用了？由於Springboot已經爲項目作了不少自動配置，因此本博客簡單跟一下源碼，瞭解一下SpringbootThymeleaf的自動配置

SpringBoot的自動配置類在ThymeleafAutoConfiguration裏

package org.springframework.boot.autoconfigure.thymeleaf;
....

@Configuration(proxyBeanMethods = false)//定義這是一個配置類
@EnableConfigurationProperties(ThymeleafProperties.class)//使用ThymeleafProperties屬性類的屬性
@ConditionalOnClass({ TemplateMode.class, SpringTemplateEngine.class })//指定TemplateMode、SpringTemplateEngine(模板引擎類)起效的狀況，整個配置類才起做用
@AutoConfigureAfter({ WebMvcAutoConfiguration.class, WebFluxAutoConfiguration.class })//必須在WebMvcAutoConfiguration(SpringMVC自動配置類，這個配置類會加載組裝全部的視圖解析器)、WebFluxAutoConfiguration類起效後，這個Thymeleaf自動配置類才起效
public class ThymeleafAutoConfiguration {

    //沒有自定義的模板解析器類的狀況，使用默認的模板解析器
    @Configuration(proxyBeanMethods = false)
    @ConditionalOnMissingBean(name = "defaultTemplateResolver")
    static class DefaultTemplateResolverConfiguration {

        private static final Log logger = LogFactory.getLog(DefaultTemplateResolverConfiguration.class);
        //Thymeleaf的properties配置
        private final ThymeleafProperties properties;

        private final ApplicationContext applicationContext;

        DefaultTemplateResolverConfiguration(ThymeleafProperties properties, ApplicationContext applicationContext) {
            this.properties = properties;
            this.applicationContext = applicationContext;
        }
        //用PostConstruct註解，在依賴注入完成以後，實現類的初始化配置，這個方法主要是檢查模板引擎的資源文件路徑是否有
        @PostConstruct
        void checkTemplateLocationExists() {
            boolean checkTemplateLocation = this.properties.isCheckTemplateLocation();
            if (checkTemplateLocation) {
                TemplateLocation location = new TemplateLocation(this.properties.getPrefix());
                if (!location.exists(this.applicationContext)) {
                    logger.warn("Cannot find template location: " + location + " (please add some templates or check "
                            + "your Thymeleaf configuration)");
                }
            }
        }
        //默認的Thymeleaf資源解析器
        @Bean
        SpringResourceTemplateResolver defaultTemplateResolver() {
            SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
            //資源解析器的全部配置
            resolver.setApplicationContext(this.applicationContext);
            resolver.setPrefix(this.properties.getPrefix());
            resolver.setSuffix(this.properties.getSuffix());
            resolver.setTemplateMode(this.properties.getMode());
            if (this.properties.getEncoding() != null) {
                resolver.setCharacterEncoding(this.properties.getEncoding().name());
            }
            resolver.setCacheable(this.properties.isCache());
            Integer order = this.properties.getTemplateResolverOrder();
            if (order != null) {
                resolver.setOrder(order);
            }
            resolver.setCheckExistence(this.properties.isCheckTemplate());
            return resolver;
        }

    }
    //又是Thymeleaf的自動配置，自動配置模板引擎SpringTemplateEngine
    @Configuration(proxyBeanMethods = false)
    protected static class ThymeleafDefaultConfiguration {

        @Bean
        @ConditionalOnMissingBean(ISpringTemplateEngine.class)
        SpringTemplateEngine templateEngine(ThymeleafProperties properties,
                ObjectProvider<ITemplateResolver> templateResolvers, ObjectProvider<IDialect> dialects) {
            SpringTemplateEngine engine = new SpringTemplateEngine();
            engine.setEnableSpringELCompiler(properties.isEnableSpringElCompiler());
            engine.setRenderHiddenMarkersBeforeCheckboxes(properties.isRenderHiddenMarkersBeforeCheckboxes());
            templateResolvers.orderedStream().forEach(engine::addTemplateResolver);
            dialects.orderedStream().forEach(engine::addDialect);
            return engine;
        }

    }

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnWebApplication(type = Type.SERVLET)
    @ConditionalOnProperty(name = "spring.thymeleaf.enabled", matchIfMissing = true)
    static class ThymeleafWebMvcConfiguration {

        @Bean
        @ConditionalOnEnabledResourceChain
        @ConditionalOnMissingFilterBean(ResourceUrlEncodingFilter.class)
        FilterRegistrationBean<ResourceUrlEncodingFilter> resourceUrlEncodingFilter() {
            FilterRegistrationBean<ResourceUrlEncodingFilter> registration = new FilterRegistrationBean<>(
                    new ResourceUrlEncodingFilter());
            registration.setDispatcherTypes(DispatcherType.REQUEST, DispatcherType.ERROR);
            return registration;
        }
        //比較重要的視圖解析器配置
        @Configuration(proxyBeanMethods = false)
        static class ThymeleafViewResolverConfiguration {

            @Bean
            @ConditionalOnMissingBean(name = "thymeleafViewResolver")
            ThymeleafViewResolver thymeleafViewResolver(ThymeleafProperties properties,
                    SpringTemplateEngine templateEngine) {
                ThymeleafViewResolver resolver = new ThymeleafViewResolver();
                //設置模板引擎
                resolver.setTemplateEngine(templateEngine);
        //字符編碼設置
                        resolver.setCharacterEncoding(properties.getEncoding().name());
                resolver.setContentType(
                        appendCharset(properties.getServlet().getContentType(), resolver.getCharacterEncoding()));
                resolver.setProducePartialOutputWhileProcessing(
                        properties.getServlet().isProducePartialOutputWhileProcessing());
                resolver.setExcludedViewNames(properties.getExcludedViewNames());
                resolver.setViewNames(properties.getViewNames());
                // This resolver acts as a fallback resolver (e.g. like a
                // InternalResourceViewResolver) so it needs to have low precedence
                resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 5);
                //Thymeleaf緩存
                resolver.setCache(properties.isCache());
                return resolver;
            }

            private String appendCharset(MimeType type, String charset) {
                if (type.getCharset() != null) {
                    return type.toString();
                }
                LinkedHashMap<String, String> parameters = new LinkedHashMap<>();
                parameters.put("charset", charset);
                parameters.putAll(type.getParameters());
                return new MimeType(type, parameters).toString();
            }

        }

    }

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnWebApplication(type = Type.REACTIVE)
    @ConditionalOnProperty(name = "spring.thymeleaf.enabled", matchIfMissing = true)
    static class ThymeleafReactiveConfiguration {

        @Bean
        @ConditionalOnMissingBean(ISpringWebFluxTemplateEngine.class)
        SpringWebFluxTemplateEngine templateEngine(ThymeleafProperties properties,
                ObjectProvider<ITemplateResolver> templateResolvers, ObjectProvider<IDialect> dialects) {
            SpringWebFluxTemplateEngine engine = new SpringWebFluxTemplateEngine();
            engine.setEnableSpringELCompiler(properties.isEnableSpringElCompiler());
            engine.setRenderHiddenMarkersBeforeCheckboxes(properties.isRenderHiddenMarkersBeforeCheckboxes());
            templateResolvers.orderedStream().forEach(engine::addTemplateResolver);
            dialects.orderedStream().forEach(engine::addDialect);
            return engine;
        }

    }
    //ThymeleafWebFluxConfiguration自動配置
    @Configuration(proxyBeanMethods = false)
    @ConditionalOnWebApplication(type = Type.REACTIVE)
    @ConditionalOnProperty(name = "spring.thymeleaf.enabled", matchIfMissing = true)
    static class ThymeleafWebFluxConfiguration {

        @Bean
        @ConditionalOnMissingBean(name = "thymeleafReactiveViewResolver")
        ThymeleafReactiveViewResolver thymeleafViewResolver(ISpringWebFluxTemplateEngine templateEngine,
                ThymeleafProperties properties) {
            ThymeleafReactiveViewResolver resolver = new ThymeleafReactiveViewResolver();
            resolver.setTemplateEngine(templateEngine);
            mapProperties(properties, resolver);
            mapReactiveProperties(properties.getReactive(), resolver);
            // This resolver acts as a fallback resolver (e.g. like a
            // InternalResourceViewResolver) so it needs to have low precedence
            resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 5);
            return resolver;
        }

        private void mapProperties(ThymeleafProperties properties, ThymeleafReactiveViewResolver resolver) {
            PropertyMapper map = PropertyMapper.get();
            map.from(properties::getEncoding).to(resolver::setDefaultCharset);
            resolver.setExcludedViewNames(properties.getExcludedViewNames());
            resolver.setViewNames(properties.getViewNames());
        }

        private void mapReactiveProperties(Reactive properties, ThymeleafReactiveViewResolver resolver) {
            PropertyMapper map = PropertyMapper.get();
            map.from(properties::getMediaTypes).whenNonNull().to(resolver::setSupportedMediaTypes);
            map.from(properties::getMaxChunkSize).asInt(DataSize::toBytes).when((size) -> size > 0)
                    .to(resolver::setResponseMaxChunkSizeBytes);
            map.from(properties::getFullModeViewNames).to(resolver::setFullModeViewNames);
            map.from(properties::getChunkedModeViewNames).to(resolver::setChunkedModeViewNames);
        }

    }

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnClass(LayoutDialect.class)
    static class ThymeleafWebLayoutConfiguration {

        @Bean
        @ConditionalOnMissingBean
        LayoutDialect layoutDialect() {
            return new LayoutDialect();
        }

    }

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnClass(DataAttributeDialect.class)
    static class DataAttributeDialectConfiguration {

        @Bean
        @ConditionalOnMissingBean
        DataAttributeDialect dialect() {
            return new DataAttributeDialect();
        }

    }

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnClass({ SpringSecurityDialect.class })
    static class ThymeleafSecurityDialectConfiguration {

        @Bean
        @ConditionalOnMissingBean
        SpringSecurityDialect securityDialect() {
            return new SpringSecurityDialect();
        }

    }

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnClass(Java8TimeDialect.class)
    static class ThymeleafJava8TimeDialect {

        @Bean
        @ConditionalOnMissingBean
        Java8TimeDialect java8TimeDialect() {
            return new Java8TimeDialect();
        }

    }

}

ThymeleafProperties是SpringBoot的屬性配置類，使用ConfigurationProperties註解進行屬性映射

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

    private static final Charset DEFAULT_ENCODING = StandardCharsets.UTF_8;
    //默認的模板資源路徑
    public static final String DEFAULT_PREFIX = "classpath:/templates/";
    //默認解析html資源
    public static final String DEFAULT_SUFFIX = ".html";

    /**
     * Whether to check that the template exists before rendering it.
     */
    private boolean checkTemplate = true;

    /**
     * Whether to check that the templates location exists.
     */
    private boolean checkTemplateLocation = true;

    /**
     * Prefix that gets prepended to view names when building a URL.
     */
    private String prefix = DEFAULT_PREFIX;

    /**
     * Suffix that gets appended to view names when building a URL.
     */
    private String suffix = DEFAULT_SUFFIX;

    /**
     * Template mode to be applied to templates. See also Thymeleaf's TemplateMode enum.
     */
     //默認模式也是html的
    private String mode = "HTML";

    /**
     * Template files encoding.
     */
    private Charset encoding = DEFAULT_ENCODING;

    /**
     * Whether to enable template caching.
     */
     //默認開啓緩存，項目沒上線建議經過配置關閉,而後按F9就能夠自動編譯，避免影響調試
    private boolean cache = true;

    ....
}

ok，而後簡單跟一下視圖解析器的源碼：Thymeleaf視圖解析器類的關鍵代碼，建立視圖view的方法，如圖，也是根據viewname進行重定向

從上面方法能夠看出進行重定向或者forward等等方法，而後調一下redirect的，看看RedirectView類，翻下源碼，找到以下關鍵代碼：

一樣在這個類裏，進行了狀態碼設置，請求頭設置，而後response.sendRedirect(encodedURL);

而forward的是經過如圖方法進行頁面跳轉：

附錄：
Thymeleaf官方例子