• 4_1.springboot2.xWeb开发使用thymeleaf


    1、简介

    如果使用SpringBoot;

    1)、创建SpringBoot应用,选中我们需要的模块;

    2)、SpringBoot已经默认将这些场景配置好了,只需要在配置文件中指定少量配置就可以运行起来

    3)、自己编写业务代码;

    自动配置原理:

    xxxxAutoConfiguration:帮我们给容器中自动配置组件;
    xxxxProperties:配置类来封装配置文件的内容;
    

    2、静态资源的映射规则

    在ResourceProperties配置文件类中

    @ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
    public class ResourceProperties {
    
    	private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
    			"classpath:/resources/", "classpath:/static/", "classpath:/public/" };
    
    	/**
    	 * Locations of static resources. Defaults to classpath:[/META-INF/resources/,
    	 * /resources/, /static/, /public/].
    	 */
    	private String[] staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
        .....
    

    可以看到静态资源的位置。

    WebMvcAuotConfiguration自动配置类

    @Override
    		public void addResourceHandlers(ResourceHandlerRegistry registry) {
    			if (!this.resourceProperties.isAddMappings()) {
    				logger.debug("Default resource handling disabled");
    				return;
    			}
    			Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
    			CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
    			if (!registry.hasMappingForPattern("/webjars/**")) {
    				customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**")
    						.addResourceLocations("classpath:/META-INF/resources/webjars/")
    						.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
    			}
                //静态资源文件夹映射
    			String staticPathPattern = this.mvcProperties.getStaticPathPattern();
    			if (!registry.hasMappingForPattern(staticPathPattern)) {
    				customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
    						.addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
    						.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
    			}
    		}
    
               //配置图标
    @Configuration
    		@ConditionalOnProperty(value = "spring.mvc.favicon.enabled", matchIfMissing = true)
    		public static class FaviconConfiguration implements ResourceLoaderAware {
    
    			private final ResourceProperties resourceProperties;
    
    			private ResourceLoader resourceLoader;
    
    			public FaviconConfiguration(ResourceProperties resourceProperties) {
    				this.resourceProperties = resourceProperties;
    			}
    
    			@Override
    			public void setResourceLoader(ResourceLoader resourceLoader) {
    				this.resourceLoader = resourceLoader;
    			}
    
    			@Bean
    			public SimpleUrlHandlerMapping faviconHandlerMapping() {
    				SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
    				mapping.setOrder(Ordered.HIGHEST_PRECEDENCE + 1);
    				mapping.setUrlMap(Collections.singletonMap("**/favicon.ico", faviconRequestHandler()));
    				return mapping;
    			}
    
    			@Bean
    			public ResourceHttpRequestHandler faviconRequestHandler() {
    				ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
    				requestHandler.setLocations(resolveFaviconLocations());
    				return requestHandler;
    			}
    
    			private List<Resource> resolveFaviconLocations() {
    				String[] staticLocations = getResourceLocations(this.resourceProperties.getStaticLocations());
    				List<Resource> locations = new ArrayList<>(staticLocations.length + 1);
    				Arrays.stream(staticLocations).map(this.resourceLoader::getResource).forEach(locations::add);
    				locations.add(new ClassPathResource("/"));
    				return Collections.unmodifiableList(locations);
    			}
    
    		}
    
    	}
    		//配置欢迎页的映射
    @Bean
    		public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext) {
    			WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
    					new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
    					this.mvcProperties.getStaticPathPattern());
    			welcomePageHandlerMapping.setInterceptors(getInterceptors());
    			return welcomePageHandlerMapping;
    		}
    

    注意:

    1)、所有 /webjars/** ,都去 classpath:/META-INF/resources/webjars/ 找资源;

    webjars:以jar包的方式引入静态资源;

    在这里插入图片描述

    访问方式:localhost:8080/webjars/jquery/3.4.1/jquery.js

    <!--引入jquery-webjar-->在访问的时候只需要写webjars下面资源的名称即可
    		<dependency>
    			<groupId>org.webjars</groupId>
    			<artifactId>jquery</artifactId>
    			<version>3.4.1</version>
    		</dependency>
    
    			String staticPathPattern = this.mvcProperties.getStaticPathPattern();
    	/**
    

    2)、"/**" 访问当前项目的任何资源,都去(静态资源的文件夹)找映射

    "classpath:/META-INF/resources/", 
    "classpath:/resources/",
    "classpath:/static/", 
    "classpath:/public/" 
    "/":当前项目的根路径
    

    localhost:8080/abc === 去静态资源文件夹里面找abc

    3、模板引擎

    ​ Thymeleaf是一款用于渲染XML/XHTML/HTML5内容的模板引擎。类似JSP,Velocity,FreeMaker等,它也可以轻易的与Spring MVC等Web框架进行集成作为Web应用的模板引擎。与其它模板引擎相比,Thymeleaf最大的特点是能够直接在浏览器中打开并正确显示模板页面,而不需要启动整个Web应用。

    在这里插入图片描述
    SpringBoot推荐的Thymeleaf,语法更简单,功能更强大;

    1、引入thymeleaf

    <!--引入thymeleaf-->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-thymeleaf</artifactId>
            </dependency>
    切换thymeleaf版本
    <properties>
            <java.version>1.8</java.version>
            <thymeleaf.version>3.0.11.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>2.1.1</thymeleaf-layout-dialect.version>
        </properties>
    
    

    2、Thymeleaf使用

    @ConfigurationProperties(prefix = "spring.thymeleaf")
    public class ThymeleafProperties {
    
    	private static final Charset DEFAULT_ENCODING = StandardCharsets.UTF_8;
    
    	public static final String DEFAULT_PREFIX = "classpath:/templates/";
    
    	public static final String DEFAULT_SUFFIX = ".html";
    

    只要我们把HTML页面放在classpath:/templates/,thymeleaf就能自动渲染;

    使用:

    1、导入thymeleaf的名称空间

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

    2、使用thymeleaf语法;

    <!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)、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

    在这里插入图片描述

    常用表达式:

    ${...}  变量表达式
    *{...}  选择表达式
    #{...}  消息文字表达式
    @{...}  链接url表达式
    #maps   工具对象表达式
    

    常用标签:

    th:action  定义后台控制器路径
    th:each  循环语句
    th:field  表单字段绑定
    th:href 定义超链接
    th:id  div标签中的id声明,类似html标签中的id属性
    th:if  条件判断语句
    th:include  布局标签,替换内容到引入文件
    th:fragment  布局标签,定义一个代码片段,方便其它地方引用
    th:object  替换对象
    th:src  图片类地址引入
    th:text  显示文本
    th:value  属性赋值
    常用函数:
    #dates  日期函数
    #lists  列表函数
    #arrays  数组函数
    #strings  字符串函数
    #numbers  数字函数
    #calendars  日历函数
    #objects  对象函数
    #bools  逻辑函数
    
    

    同时我们还需要在application.properties文件中添加Thymeleaf配置,具体代码如下:

    #thymeleaf配置
    #模板的模式,支持如:HTML、XML、TEXT、JAVASCRIPT等
    spring.thymeleaf.mode=HTML5
    #编码,可不用配置
    spring.thymeleaf.encoding=UTF-8
    #内容类别,可不用配置
    spring.thymeleaf.content-type=text/html
    #开发配置为false,避免修改模板还要重启服务器
    spring.thymeleaf.cache=false
    #配置模板路径,默认就是templates,可不用配置
    #spring.thymeleaf.prefix=classpath:/templates/
    
    

    注意:Thymeleaf模板引擎默认会读取my-spring-boot项目下的资源文件夹resource下的templates目录,这个目录是用来存放HTML文件的。如果我们添加了Thymeleaf依赖,而没有进行任何配置,或者添加默认目录,启动应用时就会报错。

    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:
        			#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).
    
        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>
        
        Message Expressions: #{...}:获取国际化内容
        Link URL Expressions: @{...}:定义URL;
        		@{/order/process(execId=${execId},execType='FAST')}
        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: _ 
    
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  • 原文地址:https://www.cnblogs.com/jatpeo/p/11767486.html
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