一、自己寫的類和配置文件進行綁定（第一種方式）

1. 自己寫的類，需要和配置文件中配置的內容進行綁定（也就是說把配置文件中配置的內容綁定到自己寫的類的屬性中去），可以使用如下兩個注解實現

@Component
@ConfigurationProperties(prefix = "mycar")

/**
 * 只有在容器中的組件，才會擁有SpringBoot提供的強大功能
 */
@Component
@ConfigurationProperties(prefix = "mycar")
public class Car {

    private String brand;
    private Integer price;

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public Integer getPrice() {
        return price;
    }

    public void setPrice(Integer price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Car{" +
                "brand='" + brand + '\'' +
                ", price=" + price +
                '}';
    }
}

配置文件如下：

mycar.brand=YD
mycar.price=100000

二、SpringBoot底層的配置綁定功能（第二種方式）

? ? ? ? 為了實現自動配置功能，在SpringBoot底層會大量使用自動配置類（如?WebMvcAutoConfiguration配置類中的內部配置類WebMvcAutoConfigurationAdapter 和 屬性類?WebMvcProperties, ResourceProperties 進行綁定，在配置類里面注冊的組件,即，使用@Bean給容器中添加的組件需要一些屬性值，而這些屬性值都是從屬性類中獲取的，在屬性類中有注冊這些組件需要的默認值，但是當我們想要改變這些組件的默認值，該怎么做呢？

? ? ? ? 屬性類（xxxProperties）通過@EnableConfigurationProperties(xxxProperties.class) 和配置文件進行了綁定，所以當我們想要修改SpringBoot自動幫我們注冊到容器中的組件的屬性值時，可以直接在配置文件中進行修改即可。

? ? ? ? 看下面的源碼解釋：

    @Configuration(proxyBeanMethods = false)
	@Import(EnableWebMvcConfiguration.class)

    // 這個注解的所用是開啟WebMvcProperties和ResourceProperties的配置綁定功能，并把這兩個屬    
    // 性類添加到IOC容器中，相應的，在WebMvcProperties, ResourceProperties這兩個屬性類上，會
    // 標注@ConfigurationProperties(prefix = "spring.mvc")注解，表示和項目的配置文件 
    // (application.properties或application.yml)中以spring.mvc為前綴的配置項進行綁定
	@EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })

	@Order(0)
	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {

		private static final Log logger = LogFactory.getLog(WebMvcConfigurer.class);

		private final ResourceProperties resourceProperties;

		private final WebMvcProperties mvcProperties;

		private final ListableBeanFactory beanFactory;

		private final ObjectProvider<HttpMessageConverters> messageConvertersProvider;

		private final ObjectProvider<DispatcherServletPath> dispatcherServletPath;

		private final ObjectProvider<ServletRegistrationBean<?>> servletRegistrations;

		final ResourceHandlerRegistrationCustomizer resourceHandlerRegistrationCustomizer;

		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;
		}

		@Override
		public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
			this.messageConvertersProvider
					.ifAvailable((customConverters) -> converters.addAll(customConverters.getConverters()));
		}

		@Override
		public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
			if (this.beanFactory.containsBean(TaskExecutionAutoConfiguration.APPLICATION_TASK_EXECUTOR_BEAN_NAME)) {
				Object taskExecutor = this.beanFactory
						.getBean(TaskExecutionAutoConfiguration.APPLICATION_TASK_EXECUTOR_BEAN_NAME);
				if (taskExecutor instanceof AsyncTaskExecutor) {
					configurer.setTaskExecutor(((AsyncTaskExecutor) taskExecutor));
				}
			}
			Duration timeout = this.mvcProperties.getAsync().getRequestTimeout();
			if (timeout != null) {
				configurer.setDefaultTimeout(timeout.toMillis());
			}
		}

		@Override
		@SuppressWarnings("deprecation")
		public void configurePathMatch(PathMatchConfigurer configurer) {
			configurer.setUseSuffixPatternMatch(this.mvcProperties.getPathmatch().isUseSuffixPattern());
			configurer.setUseRegisteredSuffixPatternMatch(
					this.mvcProperties.getPathmatch().isUseRegisteredSuffixPattern());
			this.dispatcherServletPath.ifAvailable((dispatcherPath) -> {
				String servletUrlMapping = dispatcherPath.getServletUrlMapping();
				if (servletUrlMapping.equals("/") && singleDispatcherServlet()) {
					UrlPathHelper urlPathHelper = new UrlPathHelper();
					urlPathHelper.setAlwaysUseFullPath(true);
					configurer.setUrlPathHelper(urlPathHelper);
				}
			});
		}

		private boolean singleDispatcherServlet() {
			return this.servletRegistrations.stream().map(ServletRegistrationBean::getServlet)
					.filter(DispatcherServlet.class::isInstance).count() == 1;
		}

		@Override
		@SuppressWarnings("deprecation")
		public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
			WebMvcProperties.Contentnegotiation contentnegotiation = this.mvcProperties.getContentnegotiation();
			configurer.favorPathExtension(contentnegotiation.isFavorPathExtension());
			configurer.favorParameter(contentnegotiation.isFavorParameter());
			if (contentnegotiation.getParameterName() != null) {
				configurer.parameterName(contentnegotiation.getParameterName());
			}
			Map<String, MediaType> mediaTypes = this.mvcProperties.getContentnegotiation().getMediaTypes();
			mediaTypes.forEach(configurer::mediaType);
		}

		@Bean
		@ConditionalOnMissingBean
		public InternalResourceViewResolver defaultViewResolver() {
			InternalResourceViewResolver resolver = new InternalResourceViewResolver();
			resolver.setPrefix(this.mvcProperties.getView().getPrefix());
			resolver.setSuffix(this.mvcProperties.getView().getSuffix());
			return resolver;
		}

		@Bean
		@ConditionalOnBean(View.class)
		@ConditionalOnMissingBean
		public BeanNameViewResolver beanNameViewResolver() {
			BeanNameViewResolver resolver = new BeanNameViewResolver();
			resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
			return resolver;
		}

		@Bean
		@ConditionalOnBean(ViewResolver.class)
		@ConditionalOnMissingBean(name = "viewResolver", value = ContentNegotiatingViewResolver.class)
		public ContentNegotiatingViewResolver viewResolver(BeanFactory beanFactory) {
			ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver();
			resolver.setContentNegotiationManager(beanFactory.getBean(ContentNegotiationManager.class));
			// ContentNegotiatingViewResolver uses all the other view resolvers to locate
			// a view so it should have a high precedence
			resolver.setOrder(Ordered.HIGHEST_PRECEDENCE);
			return resolver;
		}

		@Bean
		@ConditionalOnMissingBean
		@ConditionalOnProperty(prefix = "spring.mvc", name = "locale")
		public LocaleResolver localeResolver() {
			if (this.mvcProperties.getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
				return new FixedLocaleResolver(this.mvcProperties.getLocale());
			}
			AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
			localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
			return localeResolver;
		}

		@Override
		public MessageCodesResolver getMessageCodesResolver() {
			if (this.mvcProperties.getMessageCodesResolverFormat() != null) {
				DefaultMessageCodesResolver resolver = new DefaultMessageCodesResolver();
				resolver.setMessageCodeFormatter(this.mvcProperties.getMessageCodesResolverFormat());
				return resolver;
			}
			return null;
		}

		@Override
		public void addFormatters(FormatterRegistry registry) {
			ApplicationConversionService.addBeans(registry, this.beanFactory);
		}

		@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));
			}
		}

		private Integer getSeconds(Duration cachePeriod) {
			return (cachePeriod != null) ? (int) cachePeriod.getSeconds() : null;
		}

		private void customizeResourceHandlerRegistration(ResourceHandlerRegistration registration) {
			if (this.resourceHandlerRegistrationCustomizer != null) {
				this.resourceHandlerRegistrationCustomizer.customize(registration);
			}
		}

		@Bean
		@ConditionalOnMissingBean({ RequestContextListener.class, RequestContextFilter.class })
		@ConditionalOnMissingFilterBean(RequestContextFilter.class)
		public static RequestContextFilter requestContextFilter() {
			return new OrderedRequestContextFilter();
		}

	}

@ConfigurationProperties(prefix = "spring.mvc")
public class WebMvcProperties {
  ...
}