4_1.springboot2.xWeb开发使用thymeleaf

r囧r小猫 2023-06-05 11:08 29阅读 0赞

# 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][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70]

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

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][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 1]  
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>
    切换thymeleaf版本
    <properties>
            <java.version>1.8</java.version>
            <thymeleaf.version>3.0.11.RELEASE</thymeleaf.version>
            
            
            <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**

**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>
        
        <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][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 2]

**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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