• 模板引擎Thymeleaf的简单了解


    模板引擎

    SpringBoot中,项目以jar包的形式打包,而不是web项目,而且使用的tomcat是嵌入式的tomcat,故不支持JSP了

    模板引擎:JSP、Velocity、Freemarker、Thymeleaf

    SpringBoot推荐的Thymeleaf;

    语法更简单,功能更强大;

    1、引入thymeleaf;

    <dependency>
    	<groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    上面引入的版本默认是2.1.6,切换thymeleaf3版本,在properties标签下加入2个标签
    <properties>
    		<thymeleaf.version>3.0.9.RELEASE</thymeleaf.version>
    		<!-- 布局功能的支持程序  thymeleaf3主程序  layout2以上版本 -->
    		<!-- thymeleaf2   layout1-->
    		<thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version>
      </properties>
    

    2、Thymeleaf使用

    @ConfigurationProperties(prefix = "spring.thymeleaf")
    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";
      	//上面是springmvc中的前缀和后缀
    

    因为默认有前缀和后缀的设置,故只要我们把HTML页面放在classpath:/templates/,thymeleaf就能自动渲染;

    使用:

    1、在html页面中导入thymeleaf的名称空间(起提示作用)

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

    2、使用thymeleaf语法,举个例子:

    <!DOCTYPE html>
    <html lang="en" xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <h1>成功!</h1>
        <!--th:text 将div里面的文本内容设置为 -->
        <div th:text="${hello}">这是显示欢迎信息</div>
    </body>
    </html>
    

    3、语法规则

    1)、简单语法规则

    例如:th:text;改变当前元素里面的文本内容;

    th:任意html属性;来替换原生属性的值

    超链接中网址中带参数,thymeleaf可以用括号表示,如果有多个参数,用逗号隔开:
    th:href="@{/index.html(l='zh_CN',user='zg')}"
    

    2)、表达式?

    Simple expressions:(表达式语法)
        1.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:
        			#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.
                    
                    ${session.foo}
                3)、内置的一些工具对象:
    #execInfo : information about the template being processed.
    #messages : methods for obtaining externalized messages inside variables expressions, in the same way as they would be obtained using #{…} syntax.
    #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.
    #ids : methods for dealing with id attributes that might be repeated (for example, as a result of an iteration).
    
        2.Selection Variable Expressions: *{...}:选择表达式:和${}在功能上是一样;
        	补充:配合 th:object="${session.user}:
               <div th:object="${session.user}">
                <p>Name: <span th:text="*{firstName}">Sebastian</span>.</p>
                <p>Surname: <span th:text="*{lastName}">Pepper</span>.</p>
                <p>Nationality: <span th:text="*{nationality}">Saturn</span>.</p>
                </div>
        
        3.Message Expressions: #{...}:获取国际化内容
        
        4.Link URL Expressions: @{...}:定义URL;
        		@{/order/process(execId=${execId},execType='FAST')}
        		
        5.Fragment Expressions: ~{...}:片段引用表达式
        		<div th:insert="~{commons :: main}">...</div>
        		
    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: _ 
    

    举例:

    <!DOCTYPE html>
    <html lang="en" xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
    <h1>成功!</h1>
    <!--th:text 将div里面的文本内容设置为 -->
    <div id="div01" class="myDiv" th:id="${hello}" th:class="${hello}" th:text="${hello}">这是显示欢迎信息</div>
    <hr/>
    <div th:text="${hello}"></div>
    <div th:utext="${hello}"></div>
    <hr/>
    <!-- th:each每次遍历都会生成当前这个标签: 3个h4 -->
    <h4 th:text="${user}"  th:each="user:${users}"></h4>
    <hr/>
    <h4>
        <span th:each="user:${users}"> [[${user}]] </span>
    </h4>
    </body>
    </html>
    

    3)、内联表达式 Expression inlining
    使用手册pdf中第12章的内容

    在Thymeleaf中,[[…]]或[(…)]之间的表达式被视为内联表达式,在其中,我们可以使用任何能在th:text或th:utext属性中用的表达式。比如说:

    <p>Hello, <span th:text="${session.user.name}">Sebastian</span>!</p>  
    等价于:
    <p>Hello, [[${session.user.name}]]!</p>
    

    在一些内联标签只能使用这个内联表达式,如下:

    <input type="checkbox" value="remember-me"/> [[#{login.remember}]]
    
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  • 原文地址:https://www.cnblogs.com/baizihua/p/12222641.html
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