太卷了！现在面试上来就问SpringBoot源码实现，CRUD工程师能招架得住吗今晚这节SpringBoot直播课千万不能错过，听完就能掌握SpringBoot源码，征服面试官

demo代码：

https://gitee.com/xqh_1_0/spring-boot.git

1、简介

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？

这个场景的SpringBoot帮我们配置了什么？能不能修改？能修改那些配置？能不能扩展？xxx

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

2、静态资源文件映射规则

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties implements ResourceLoaderAware, InitializingBean {
    //可以设置和静态资源相关的参数，缓存时间等

@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();
   if (!registry.hasMappingForPattern(staticPathPattern)) {
      customizeResourceHandlerRegistration(
            registry.addResourceHandler(staticPathPattern)
                  .addResourceLocations(
                        this.resourceProperties.getStaticLocations())
                  .setCachePeriod(cachePeriod));
   }
}

1、webjar

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

webjars：以jar包的方式引入静态资源

http://www.webjars.org/

localhost:8080/webjars/jquery/3.3.1/jquery.js

2、本地资源

private String staticPathPattern = "/**";

访问任何资源

2、会在这几文件夹下去找静态路径（静态资源文件夹）

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

localhost:8080/abc ==>去静态资源文件夹中找abc

3、index页面欢迎页，静态资源文件夹下所有的index.html页面；被“/**”映射；

localhost:8080/ -->index页面

@Bean
public WelcomePageHandlerMapping welcomePageHandlerMapping(
      ResourceProperties resourceProperties) {
   return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(),
         this.mvcProperties.getStaticPathPattern());
}

4、喜欢的图标，即网站title的图标favicon

@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);
       //把任何favicon的图标都在静态文件夹下找
      mapping.setUrlMap(Collections.singletonMap("**/favicon.ico",
            faviconRequestHandler()));
      return mapping;
   }

   @Bean
   public ResourceHttpRequestHandler faviconRequestHandler() {
      ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
      requestHandler
            .setLocations(this.resourceProperties.getFaviconLocations());
      return requestHandler;
   }

}

可以在配置文件配置静态资源文件夹

spring.resources.static-locations=classpath:xxxx

3、模板引擎

将html和数据 结合到一起 输出组装处理好的新文件

SpringBoot推荐Thymeleaf;语法简单，功能强大

1、引入thymeleaf 3

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

默认导入thymeleaf2，版本太低 所以使用thymeleaf3.

官方导入办法

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <!--thymeleaf 3的导入-->
    <thymeleaf.version>3.0.9.RELEASE</thymeleaf.version>
    <!--布局功能支持 同时支持thymeleaf3主程序 layout2.0以上版本  -->
    <!--布局功能支持 同时支持thymeleaf2主程序 layout1.0以上版本  -->
    <thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version>
</properties>

2、Thymeleaf使用和语法

@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";
   //只要把HTML文件方法类路径下的template文件夹下，就会自动导入

只要把HTML页面放到classpath:/templates/,thymeleaf就能自动渲染；

使用：

1、导入thymeleaf的名称空间

<html 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>success</title>
</head>
<body>
<h1>success</h1>
<!--th:text 将div里面的文本内容设置为-->
<div th:text="${Lion}">
前端数据
</div>
</body>
</html>

3、语法规则

1）、th:text="${hello}"可以使用任意标签 替换原生的任何属性

在SpringBoot的环境下

<div id="testid" class="testcalss" th:id="${Lion}" th:class="${Lion}" th:text="${Lion}">
	前端数据
</div>

直接访问HTML页面

2)、内联写法注意需要在body上加上 th:inline="text"敲黑板

不然不起作用

<body class="text-center" th:inline="text"></body>

th标签的访问优先级

Order Feature Attributes

3、语法规则

Simple expressions:(表达式语法)
    Variable Expressions: ${...}
    	1、获取对象属性、调用方法
    	2、使用内置基本对象：
    	    #ctx : the context object.
            #vars: the context variables.
            #locale : the context locale.
            #request : (only in Web Contexts) the HttpServletRequest object.
            #response : (only in Web Contexts) the HttpServletResponse object.
            #session : (only in Web Contexts) the HttpSession object.
            #servletContext : (only in Web Contexts) the ServletContext object.
         3、内置一些工具对象
        	#execInfo : information about the template being processed.
        	#messages : methods for obtaining externalized messages inside variables expressions, in the same way as they
            would be obtained using #{…} syntax.
            #uris : methods for escaping parts of URLs/URIs
            #conversions : methods for executing the configured conversion service (if any).
            #dates : methods for java.util.Date objects: formatting, component extraction, etc.
            #calendars : analogous to #dates , but for java.util.Calendar objects.
            #numbers : methods for formatting numeric objects.
            #strings : methods for String objects: contains, startsWith, prepending/appending, etc.
            #objects : methods for objects in general.
            #bools : methods for boolean evaluation.
            #arrays : methods for arrays.
            #lists : methods for lists.
            #sets : methods for sets.
            #maps : methods for maps.
            #aggregates : methods for creating aggregates on arrays or collections.
            #ids : methods for dealing with id attributes that might be repeated (for example, as a result of an iteration).
    Selection Variable Expressions: *{...} //选择表达式：和${}功能一样，补充功能
   # 配合th:object使用，object=${object} 以后获取就可以使用*{a}  相当于${object.a}
  	    <div th:object="${session.user}">
            <p>Name: <span th:text="*{firstName}">Sebastian</span>.</p>
            <p>Surname: <span th:text="*{lastName}">Pepper</span>.</p>
            <p>Nationality: <span th:text="*{nationality}">Saturn</span>.</p>
		</div>
    Message Expressions: #{...} //获取国际化内容
    Link URL Expressions: @{...} //定义URL链接
    	#<a href="details.html" th:href="@{/order/details(orderId=${o.id})}">view</a>
    Fragment Expressions: ~{...}//片段文档
    
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*运学**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）
    If-then: (if) ? (then)
    If-then-else: (if) ? (then) : (else)
    Default: (value) ?: (defaultvalue)
Special tokens:（空操作）
	No-Operation: _

inline写法

[[]] -->th:text
[()] -->th:utext