SpringBoot简单功能分析，静态资源访问和静态资源配置原理解析

痛定思痛。 2023-10-11 20:26 7阅读 0赞

**目录**

1、SpringMVC自动配置概览

2、简单功能分析

2.1、静态资源访问

1、静态资源目录

2、静态资源访问前缀

3、webjar

2.2、欢迎页支持

2.3、自定义 Favicon

2.4、静态资源配置原理

--------------------

## 1、SpringMVC自动配置概览 ##

官网[Web (spring.io)][Web _spring.io]

![1cf5e4c6e2cd4510b287ee3df6049d70.png][]

Spring Boot provides auto-configuration for Spring MVC that **works well with most applications.(大多场景我们都无需自定义配置)**

The auto-configuration adds the following features on top of Spring’s defaults:

*  Inclusion of `ContentNegotiatingViewResolver` and `BeanNameViewResolver` beans.

*   *  内容协商视图解析器和BeanName视图解析器

*  Support for serving static resources, including support for WebJars (covered [later in this document][])).

*   *  静态资源（包括webjars）

*  Automatic registration of `Converter`, `GenericConverter`, and `Formatter` beans.

*   *  自动注册 `Converter，GenericConverter，Formatter`

*  Support for `HttpMessageConverters` (covered [later in this document][later in this document 1]).

*   *  支持 `HttpMessageConverters` （后来我们配合内容协商理解原理）

*  Automatic registration of `MessageCodesResolver` (covered [later in this document][later in this document 2]).

*   *  自动注册 `MessageCodesResolver` （国际化用）

*  Static `index.html` support.

*   *  静态index.html 页支持

*  Custom `Favicon` support (covered [later in this document][later in this document 3]).

*   *  自定义 `Favicon`

*  Automatic use of a `ConfigurableWebBindingInitializer` bean (covered [later in this document][later in this document 4]).

*   *  自动使用 `ConfigurableWebBindingInitializer` ，（DataBinder负责将请求数据绑定到JavaBean上）

> If you want to keep those Spring Boot MVC customizations and make more [MVC customizations][] (interceptors, formatters, view controllers, and other features), you can add your own `@Configuration` class of type `WebMvcConfigurer` but **without** `@EnableWebMvc`.
> 
> **不用@EnableWebMvc注解。使用** `@Configuration` **+** `WebMvcConfigurer` **自定义规则**

> If you want to provide custom instances of `RequestMappingHandlerMapping`, `RequestMappingHandlerAdapter`, or `ExceptionHandlerExceptionResolver`, and still keep the Spring Boot MVC customizations, you can declare a bean of type `WebMvcRegistrations` and use it to provide custom instances of those components.
> 
> **声明** `WebMvcRegistrations` **改变默认底层组件**

> If you want to take complete control of Spring MVC, you can add your own `@Configuration` annotated with `@EnableWebMvc`, or alternatively add your own `@Configuration`\-annotated `DelegatingWebMvcConfiguration` as described in the Javadoc of `@EnableWebMvc`.
> 
> **使用** `@EnableWebMvc+@Configuration+DelegatingWebMvcConfiguration 全面接管SpringMVC`

## 2、简单功能分析 ##

### 2.1、静态资源访问 ###

#### 1、静态资源目录 ####

只要静态资源放在类路径下： called `/static` (or `/public` or `/resources` or `/META-INF/resources`

**访问 ： 当前项目根路径/ + 静态资源名**

**测试**

![a713a9557af64b0dbbaf991b43561f86.png][]

![a024d37493114e698c457ac36a4bcfd6.png][]

![8b5b8b29210649d8841c391e6b7a10a5.png][] ![2843d84bf271445c9e5f8efb28ef373e.png][]

原理： 静态映射/\*\*。

请求进来，先去找Controller看能不能处理。不能处理的所有请求又都交给静态资源处理器。静态资源也找不到则响应404页面

#### 2、静态资源访问前缀 ####

默认无前缀

spring:
      mvc:
        static-path-pattern: /res/**

当前项目 + static-path-pattern + 静态资源名 = 静态资源文件夹下找

**测试**

![282f4c0aaabc40bbb60ba12aa49b2a1c.png][]

![ab1f36a2e53b44edbdd78700468f7b2a.png][]

#### 3、webjar ####

自动映射 /[webjars][]/\*\*

[WebJars - Web Libraries in Jars][]

<dependency>
                <groupId>org.webjars</groupId>
                <artifactId>jquery</artifactId>
                <version>3.5.1</version>
            </dependency>

访问地址：[http://localhost:8080/webjars/jquery/3.5.1/jquery.js][webjars] 后面地址要按照依赖里面的包路径

### 2.2、欢迎页支持 ###

*  静态资源路径下 index.html
    
     *  可以配置静态资源路径
     *  但是不可以配置静态资源的访问前缀。否则导致 index.html不能被默认访问

spring:
    #  mvc:
    #    static-path-pattern: /res/**   这个会导致welcome page功能失效
    
      resources:
        static-locations: [classpath:/haha/]

*  自己创建一个能处理/index的controller

官网：[Web (spring.io)][Web _spring.io 1]

![d430d21bdb2547869d65d8fb4bbec6b7.png][]

![361ef296a0c34858bd8a3e501afc76d9.png][]![5641d6814a9a428486fdee9f943a3ae3.png][]

### 2.3、自定义 `Favicon` ###

favicon.ico 为命名的图片 放在静态资源目录下即可。

spring:
    #  mvc:
    #    static-path-pattern: /res/**   这个会导致 Favicon 功能失效

我这里放置的是阿帕奇的图片

![4a51373a8a764d6baa2dd2d0f8829140.png][]

### 2.4、静态资源配置原理 ###

●SpringBoot启动默认加载 xxxAutoConfiguration 类（自动配置类）  
●SpringMVC功能的自动配置类 WebMvcAutoConfiguration（路径：外部库->spring-boot -autoconfiguration->autoconfigure->webservlet->WebMvcAutoConfiguration），Conditional条件满足，生效

@Configuration(proxyBeanMethods = false)
    @ConditionalOnWebApplication(type = Type.SERVLET)
    @ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
    @ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
    @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
    @AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
    		ValidationAutoConfiguration.class })
    public class WebMvcAutoConfiguration {}

*  给容器中配了什么。

@Configuration(proxyBeanMethods = false)
    	@Import(EnableWebMvcConfiguration.class)
    	@EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })
    	@Order(0)
    	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {}

![ecd0718e86e742f4a81b284deb4dad3f.png][]

![50a96d5a1bb742e891d30d94fd0a0dfc.png][]

*  配置文件的相关属性和xxx进行了绑定。WebMvcProperties==**spring.mvc**、ResourceProperties==**spring.resources**

**1、配置类只有一个有参构造器**

//有参构造器所有参数的值都会从容器中确定
    //ResourceProperties resourceProperties；获取和spring.resources绑定的所有的值的对象
    //WebMvcProperties mvcProperties 获取和spring.mvc绑定的所有的值的对象
    //ListableBeanFactory beanFactory Spring的beanFactory
    //HttpMessageConverters 找到所有的HttpMessageConverters
    //ResourceHandlerRegistrationCustomizer 找到 资源处理器的自定义器。=========
    //DispatcherServletPath  DispatcherServlet的路径
    //ServletRegistrationBean   给应用注册Servlet、Filter....
    	public WebMvcAutoConfigurationAdapter(ResourceProperties resourceProperties, WebMvcProperties mvcProperties,
    				ListableBeanFactory beanFactory, ObjectProvider<HttpMessageConverters> messageConvertersProvider,
    				ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider,
    				ObjectProvider<DispatcherServletPath> dispatcherServletPath,
    				ObjectProvider<ServletRegistrationBean<?>> servletRegistrations) {
    			this.resourceProperties = resourceProperties;
    			this.mvcProperties = mvcProperties;
    			this.beanFactory = beanFactory;
    			this.messageConvertersProvider = messageConvertersProvider;
    			this.resourceHandlerRegistrationCustomizer = resourceHandlerRegistrationCustomizerProvider.getIfAvailable();
    			this.dispatcherServletPath = dispatcherServletPath;
    			this.servletRegistrations = servletRegistrations;
    		}

**2、资源处理的默认规则**

@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();
    			//webjars的规则
                if (!registry.hasMappingForPattern("/webjars/**")) {
    				customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**")
    						.addResourceLocations("classpath:/META-INF/resources/webjars/")
    						.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
    			}
                
                //
    			String staticPathPattern = this.mvcProperties.getStaticPathPattern();
    			if (!registry.hasMappingForPattern(staticPathPattern)) {
    				customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
    						.addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
    						.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
    			}
    		}

**3、欢迎页的处理规则**

HandlerMapping：处理器映射。保存了每一个Handler能处理哪些请求。	
    
    	@Bean
    		public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
    				FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
    			WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
    					new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
    					this.mvcProperties.getStaticPathPattern());
    			welcomePageHandlerMapping.setInterceptors(getInterceptors(mvcConversionService, mvcResourceUrlProvider));
    			welcomePageHandlerMapping.setCorsConfigurations(getCorsConfigurations());
    			return welcomePageHandlerMapping;
    		}
    
    	WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders,
    			ApplicationContext applicationContext, Optional<Resource> welcomePage, String staticPathPattern) {
    		if (welcomePage.isPresent() && "/**".equals(staticPathPattern)) {
                /*要用欢迎页功能，必须是/**
                这也是为什么我们前面设置静态资源访问路径而欢迎页和favicon没生效的原因
                因为人家底层已经写死了*/
    			logger.info("Adding welcome page: " + welcomePage.get());
    			setRootViewName("forward:index.html");
    		}
    		else if (welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
                // 调用Controller  /index
    			logger.info("Adding welcome page template: index");
    			setRootViewName("index");
    		}
    	}

##  ##

[Web _spring.io]: https://docs.spring.io/spring-boot/docs/current/reference/html/web.html#web.servlet.spring-mvc
[1cf5e4c6e2cd4510b287ee3df6049d70.png]: https://img-blog.csdnimg.cn/1cf5e4c6e2cd4510b287ee3df6049d70.png
[later in this document]: https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-spring-mvc-static-content
[later in this document 1]: https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-spring-mvc-message-converters
[later in this document 2]: https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-spring-message-codes
[later in this document 3]: https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-spring-mvc-favicon
[later in this document 4]: https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-spring-mvc-web-binding-initializer
[MVC customizations]: https://docs.spring.io/spring/docs/5.2.9.RELEASE/spring-framework-reference/web.html#mvc
[a713a9557af64b0dbbaf991b43561f86.png]: https://img-blog.csdnimg.cn/a713a9557af64b0dbbaf991b43561f86.png
[a024d37493114e698c457ac36a4bcfd6.png]: https://img-blog.csdnimg.cn/a024d37493114e698c457ac36a4bcfd6.png
[8b5b8b29210649d8841c391e6b7a10a5.png]: https://img-blog.csdnimg.cn/8b5b8b29210649d8841c391e6b7a10a5.png
[2843d84bf271445c9e5f8efb28ef373e.png]: https://img-blog.csdnimg.cn/2843d84bf271445c9e5f8efb28ef373e.png
[282f4c0aaabc40bbb60ba12aa49b2a1c.png]: https://img-blog.csdnimg.cn/282f4c0aaabc40bbb60ba12aa49b2a1c.png
[ab1f36a2e53b44edbdd78700468f7b2a.png]: https://img-blog.csdnimg.cn/ab1f36a2e53b44edbdd78700468f7b2a.png
[webjars]: http://localhost:8080/webjars/jquery/3.5.1/jquery.js
[WebJars - Web Libraries in Jars]: https://www.webjars.org/
[Web _spring.io 1]: https://docs.spring.io/spring-boot/docs/current/reference/html/web.html#web.servlet.spring-mvc.welcome-page
[d430d21bdb2547869d65d8fb4bbec6b7.png]: https://img-blog.csdnimg.cn/d430d21bdb2547869d65d8fb4bbec6b7.png
[361ef296a0c34858bd8a3e501afc76d9.png]: https://img-blog.csdnimg.cn/361ef296a0c34858bd8a3e501afc76d9.png
[5641d6814a9a428486fdee9f943a3ae3.png]: https://img-blog.csdnimg.cn/5641d6814a9a428486fdee9f943a3ae3.png
[4a51373a8a764d6baa2dd2d0f8829140.png]: https://img-blog.csdnimg.cn/4a51373a8a764d6baa2dd2d0f8829140.png
[ecd0718e86e742f4a81b284deb4dad3f.png]: https://img-blog.csdnimg.cn/ecd0718e86e742f4a81b284deb4dad3f.png
[50a96d5a1bb742e891d30d94fd0a0dfc.png]: https://img-blog.csdnimg.cn/50a96d5a1bb742e891d30d94fd0a0dfc.png