简介：
- 使用Springboot应用，选中需要的模块，
- Spring已经默认将场景配置好了，只需在配置文件中少量配置就可以运行起来
- 自己编写业务代码
自动配置原理
这个场景Springboot帮我们配置了什么、能不能修改呢？能修改哪些配置？
xxxxxAutoConfiguration ：帮我们给容器自动配置组件
xxxproperties 配置类来封装配置文件的内容
Springboot对静态资源的映射规则
@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false) public class ResourceProperties implements ResourceLoaderAware { //可以设置和静态资源有关的参数，缓存时间等 ｝ //webMVC的自动配置 WebMvcAuotConfiguration： @Override public void addResourceHandlers(ResourceHandlerRegistry registry) { if (!this.resourceProperties.isAddMappings()) { logger.debug("Default resource handling disabled"); return; } Integer cachePeriod = this.resourceProperties.getCachePeriod(); if (!registry.hasMappingForPattern("/webjars/**")) { customizeResourceHandlerRegistration( registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/").setCachePeriod(cachePeriod)); } String staticPathPattern = this.mvcProperties.getStaticPathPattern(); //静态资源文件夹映射 if (!registry.hasMappingForPattern(staticPathPattern)) { customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern).addResourceLocations(this.resourceProperties.getStaticLocations()).setCachePeriod(cachePeriod)); } } //配置欢迎页映射 默认识别我们template下的index.html; 页面 @Bean public WelcomePageHandlerMapping welcomePageHandlerMapping(ResourceProperties resourceProperties) { return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(), this.mvcProperties.getStaticPathPattern()); } //配置喜欢的图标 即我们网页标签最左边的图标 @Configuration @ConditionalOnProperty(value = "spring.mvc.favicon.enabled", matchIfMissing = true) public static class FaviconConfiguration { private final ResourceProperties resourceProperties; public FaviconConfiguration(ResourceProperties resourceProperties) {this.resourceProperties = resourceProperties; } @Bean public SimpleUrlHandlerMapping faviconHandlerMapping() { SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping(); mapping.setOrder(Ordered.HIGHEST_PRECEDENCE + 1); //所有 **/favicon.ico mapping.setUrlMap(Collections.singletonMap("**/favicon.ico",faviconRequestHandler())); return mapping; } @Bean public ResourceHttpRequestHandler faviconRequestHandler() { ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler(); requestHandler.setLocations(this.resourceProperties.getFaviconLocations()); return requestHandler; } }
静态资源的映射
- 所有的 /webjars/** 都去 classpath:/META-INF/resources/webjars/ 找资源；
pom.xml 依赖：
<!--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>3.3.1</version> </dependency>
访问地址：localhost:8080/webjars/jquery/3.3.1/jquery.js
-
"/**" 访问当前项目的任何资源，都去（静态资源的文件夹）找映射 （以下路径优先级从上往下）
"classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/" "/"：当前项目的根路径localhost:8080/abc === 默认去静态资源文件夹里面找abc
- 欢迎页； 静态资源文件夹下的所有index.html页面；被"/**"映射；
- localhost:8080/ 找index页面
- 所有的 **/favicon.ico 都是在静态资源文件下找；
模板引擎
常用的模板引擎有：JSP，Velocity、Freemarker、Thymeleaf
Springboot 推荐使用thymeleaf ，语法更简单，功能更强大。
引入thymeleaf
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
SpringBoot默认的thymeleaf 版本为 2.1.6 ，该版本太低，所以我们需要手动切换thymeleaf版本
<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>
SpringBoot 的其他默认版本的依赖也是这样切换，如果需要修改的话，一样的切换思路。
配置上面这两个的时候，启动Springboot 会报错误
An attempt was made to call the method org.thymeleaf.spring5.SpringTemplateEngine.setRenderHiddenMarkersBeforeCheckboxes(Z)V but it does not exist. Its class, org.thymeleaf.spring5.SpringTemplateEngine, is available from the following locations:
jar:file:/E:/springboot/repository/org/thymeleaf/thymeleaf-spring5/3.0.9.RELEASE/thymeleaf-spring5-3.0.9.RELEASE.jar!/org/thymeleaf/spring5/SpringTemplateEngine.class
It was loaded from the following location:
file:/E:/springboot/repository/org/thymeleaf/thymeleaf-spring5/3.0.9.RELEASE/thymeleaf-spring5-3.0.9.RELEASE.jar
Action:
Correct the classpath of your application so that it contains a single, compatible version of org.thymeleaf.spring5.SpringTemplateEngine
修改为以下即可：
thymeleaf的使用
配置：
@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");
//只要我们把HTML页面放在classpath:/templates/，thymeleaf就能自动渲染；
public static final String DEFAULT_PREFIX = "classpath:/templates/";
public static final String DEFAULT_SUFFIX = ".html";
使用：
1，在html 页面上导入thymeleaf的命名空间 ， 不导入也可以，只是在写代码的时候，没有相应的代码提示。
<html lang="en" xmlns:th="http://www.thymeleaf.org">
thymeleaf的语法
<!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>
语法规则：
1）、th:text；改变当前元素里面的文本内容；
2）、表达式
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: _