SpringBoot与web开发(一)-----SpringBoot快速使用

1. 开始使用

1. 创建springBoot 应用 选择需要的模块

1. SpringBoot 已经为我们把需要的配置自动装配好，只需要在后续的开发中，在配置文件中进行设置即可

2. 编写代码

2. 自动配置

XXXXXAutoConfiguration  ：在容器中自动配置组件
XXXXXProperties  ： 配置类

这些文件都在通过Mavan引入的外部库中，org.springframework.boot.autoconfigure。

3. 静态资源映射规则

默认创建的 SpringBoot 项目是没有web文件夹的，那如何映射css，js等静态资源呢？

Spring boot 会自动装配WebMvcAutoConfiguration类，会对静态资源的映射做出规定,

@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));
			}
			String staticPathPattern = this.mvcProperties.getStaticPathPattern();
			if (!registry.hasMappingForPattern(staticPathPattern)) {
				customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
						.addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
						.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
			}
		}

1. 所有webjars/**都会在classpath:/META-INF/resources/webjars/下面去找资源

• webjars : 以jar的形式引入 （https://www.webjars.org/）
• 好处： （1）将静态资源版本化，更利于升级和维护 （2）剥离静态资源，提高编译速度和打包效率（3）实现资源共享，有利于统一前端开发。
• 访问资源 localhost：8080/webjars/jquery/3.4.1/jquery.js

• pom.xml

  <dependency>
          <groupId>org.webjars</groupId>
          <artifactId>jquery</artifactId>
          <version>3.4.1</version>
      </dependency>
  

2. **/ 当前项目下的任何资源

@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/" };

默认寻找静态资源的文件夹路径：

• classpath:/META-INF/resources/
• classpath:/resources/
• classpath:/static/
• classpath:/public/
• /

例如： localhost：8080/XXX 默认就去以上路径去找

3. 映射index页面

@Bean
public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext) {
   return new WelcomePageHandlerMapping(new TemplateAvailabilityProviders(applicationContext),
         applicationContext, getWelcomePage(), this.mvcProperties.getStaticPathPattern());
}

*满足访问/* 的访问路径 **

例如：localhost：8080/

4. 页面的小图标 favicon

@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);
			}

		}

• 默认就是启动的

• 同样是满足/**的映射路径

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