SpringBoot - SpringMVC的默认配置与修改

【1】SpringBoot对SpringMVC的默认配置

官网地址如下：

https://docs.spring.io/spring-boot/docs/2.1.0.BUILD-SNAPSHOT/reference/htmlsingle/#boot-features-spring-mvc-auto-configuration

如下图所示，SpringBoot提供了SpringMVC的自动配置帮助进行Web项目开发。

翻译如下：

① 配置了视图解析器bean；
② 静态资源访问支持，包括WebJars；
③ 注册了转换器和格式化器；
④ 请求响应信息转换器；
⑤ 注册信息校验解析器–定义错误代码生成规则；
⑥ 静态页面index.html支持(欢迎页)；
⑦ 项目浏览器图标支持；
⑧ 可配置web数据绑定初始化器bean的自动使用。

【2】Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.

ContentNegotiatingViewResolver：组合所有的视图解析器的，源码分析如下。

首先在WebMvcAutoConfiguration配置类中添加组件ContentNegotiatingViewResolver。

@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));
    //注意这里
    // 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;
}

ContentNegotiatingViewResolver类如下：

public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
        implements ViewResolver, Ordered, InitializingBean {

    private ContentNegotiationManager contentNegotiationManager;

    private final ContentNegotiationManagerFactoryBean cnmFactoryBean = new ContentNegotiationManagerFactoryBean();

    private boolean useNotAcceptableStatusCode = false;

    private List<View> defaultViews;

    private List<ViewResolver> viewResolvers;
    // 这里有一个视图解析器list

    private int order = Ordered.HIGHEST_PRECEDENCE;
    //...
}

其initServletContext方法如下：

@Override
    protected void initServletContext(ServletContext servletContext) {
        Collection<ViewResolver> matchingBeans =
                BeanFactoryUtils.beansOfTypeIncludingAncestors(getApplicationContext(), ViewResolver.class).values();
        if (this.viewResolvers == null) {
            this.viewResolvers = new ArrayList<ViewResolver>(matchingBeans.size());
            for (ViewResolver viewResolver : matchingBeans) {
                if (this != viewResolver) {
                    this.viewResolvers.add(viewResolver);
                }
            }
        }
        else {
            for (int i = 0; i < viewResolvers.size(); i++) {
                if (matchingBeans.contains(viewResolvers.get(i))) {
                    continue;
                }
                String name = viewResolvers.get(i).getClass().getName() + i;
                getApplicationContext().getAutowireCapableBeanFactory().initializeBean(viewResolvers.get(i), name);
            }

        }
        if (this.viewResolvers.isEmpty()) {
            logger.warn("Did not find any ViewResolvers to delegate to; please configure them using the " +
                    "'viewResolvers' property on the ContentNegotiatingViewResolver");
        }
        AnnotationAwareOrderComparator.sort(this.viewResolvers);
        this.cnmFactoryBean.setServletContext(servletContext);
    }

即，拿到系统中所有的视图解析器！

那么如何定制自己的视图解析器呢？

可以自己给容器中添加一个视图解析器，SpringBoot 会自动的将其组合进来。

示例如下(使用@Bean在容器中添加自己的视图解析器)：

    @Bean
    public ViewResolver myViewReolver(){
        return new MyViewResolver();
    }

【3】Automatic registration of Converter, GenericConverter, and Formatter beans.

Converter：转换器；如页面表单数据到后台public String hello(User user)：类型转换使用Converter。

Formatter 格式化器； 如页面表单中日期2017.12.17到后台Date。

源码如下：

@Bean
@ConditionalOnProperty(prefix = "spring.mvc", name = "date-format")
public Formatter<Date> dateFormatter() {
    return new DateFormatter(this.mvcProperties.getDateFormat());
}

@Override
public void addFormatters(FormatterRegistry registry) {
    for (Converter<?, ?> converter : getBeansOfType(Converter.class)) {
        registry.addConverter(converter);
    }
    //自己添加的格式化器转换器，我们只需要放在容器中即可
    for (GenericConverter converter : getBeansOfType(GenericConverter.class)) {
        registry.addConverter(converter);
    }
    for (Formatter<?> formatter : getBeansOfType(Formatter.class)) {
        registry.addFormatter(formatter);
    }
}

private <T> Collection<T> getBeansOfType(Class<T> type) {
    return this.beanFactory.getBeansOfType(type).values();
}

其中默认的日期格式如下：

    /**
     * Date format to use (e.g. dd/MM/yyyy).
     */
    private String dateFormat;

通常需要在配置文件中修改：

spring.mvc.date-format=yyyy-MM-dd//根据需要自定义

【4】HttpMessageConverters

SpringMVC用来转换Http请求和响应的，如将返回值User对象转换为JSON类型。SpringBoot默认从容器中获取所有的HttpMessageConverter。

如果自己给容器中添加HttpMessageConverter，则只需将自己的组件注册到容器中。

官方文档说明如下：

Spring MVC uses the HttpMessageConverter interface to convert HTTP requests and responses. Sensible defaults are included out of the box. For example, objects can be automatically converted to JSON (by using the Jackson library) or XML (by using the Jackson XML extension, if available, or by using JAXB if the Jackson XML extension is not available). By default, strings are encoded in UTF-8.

If you need to add or customize converters, you can use Spring Boot’s HttpMessageConverters class, as shown in the following listing:

import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
import org.springframework.context.annotation.*;
import org.springframework.http.converter.*;

@Configuration
public class MyConfiguration {

    @Bean
    public HttpMessageConverters customConverters() {
        HttpMessageConverter<?> additional = ...
        HttpMessageConverter<?> another = ...
        return new HttpMessageConverters(additional, another);
    }

}

SpringBoot中，返回类型为type bean或map时，将会自动转换为JSON，使用的转换器为MappingJackson2HttpMessageConverter，源码如下：

/**
 * Implementation of {@link org.springframework.http.converter.HttpMessageConverter} that can read and
 * write JSON using <a href="http://wiki.fasterxml.com/JacksonHome">Jackson 2.x's</a> {@link ObjectMapper}.
 *
 * <p>This converter can be used to bind to typed beans, or untyped {@code HashMap} instances.
 *
 * <p>By default, this converter supports {@code application/json} and {@code application/*+json}
 * with {@code UTF-8} character set. This can be overridden by setting the
 * {@link #setSupportedMediaTypes supportedMediaTypes} property.
 *
 * <p>The default constructor uses the default configuration provided by {@link Jackson2ObjectMapperBuilder}.
 *
 * <p>Compatible with Jackson 2.6 and higher, as of Spring 4.3.
 *
 * @author Arjen Poutsma
 * @author Keith Donald
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @author Sebastien Deleuze
 * @since 3.1.2
 */
public class MappingJackson2HttpMessageConverter extends AbstractJackson2HttpMessageConverter {
//...
}

【5】修改SpringBoot的默认配置

首先说明一下几点：

1SpringBoot在自动配置很多组件的时候，先看容器中有没有用户自己配置的（@Bean、@Component）如果有就用用户配置的，如果没有，才自动配置；如果有些组件可以有多个（ViewResolver）将用户配置的和自己默认的组合起来；

2）、在SpringBoot中会有非常多的xxxConfigurer帮助我们进行扩展配置；

3）、在SpringBoot中会有很多的xxxCustomizer帮助我们进行定制配置。

其次，官网文档说明如下：

If you want to keep Spring Boot MVC features and you want to add additional MVC configuration (interceptors, formatters, view controllers, and other features), you can add your own @Configuration class of type WebMvcConfigurer but without @EnableWebMvc.

If you wish to provide custom instances of RequestMappingHandlerMapping, RequestMappingHandlerAdapter, or ExceptionHandlerExceptionResolver, you can declare a WebMvcRegistrationsAdapter instance to provide such components.

If you want to take complete control of Spring MVC, you can add your own @Configuration annotated with @EnableWebMvc.

5.1 扩展默认配置

如下，编写一个配置类，是WebMvcConfigurerAdapter类型，不能标注@EnableWebMvc：

@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {

    //重写方法
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
       // super.addViewControllers(registry);
       //浏览器发送 /success 请求来到 success
        registry.addViewController("/success").setViewName("success");
    }
    //添加组件
    @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }

其中viewController对应以前SpringMVC的xml配置如下：

<mvc:view‐controller path="/success" view‐name="success"/>

原理分析源码如下：

① WebMvcAutoConfiguration是SpringMVC的自动配置类；

② 在做其他自动配置时会导入；@Import(EnableWebMvcConfiguration.class)

@Configuration
@Import(EnableWebMvcConfiguration.class)//这里
@EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })
public static class WebMvcAutoConfigurationAdapter extends WebMvcConfigurerAdapter {

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

    private final ResourceProperties resourceProperties;

    private final WebMvcProperties mvcProperties;

    private final ListableBeanFactory beanFactory;

    private final HttpMessageConverters messageConverters;

    final ResourceHandlerRegistrationCustomizer resourceHandlerRegistrationCustomizer;
    //...
}

EnableWebMvcConfiguration类如下：

@Configuration
public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
    //...
}

同样是个配置类，继承DelegatingWebMvcConfiguration ，其类如下：

@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {

private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
//拿到系统中所有的WebMvcConfigurer
@Autowired(required = false)
public void setConfigurers(List<WebMvcConfigurer> configurers) {
    if (!CollectionUtils.isEmpty(configurers)) {
        this.configurers.addWebMvcConfigurers(configurers);
    }
}
//...
}

WebMvcConfigurerAdapter是WebMvcConfigurer的实现类，WebMvcAutoConfigurationAdapter继承自WebMvcConfigurerAdapter。

总结 ： 容器中所有的WebMvcConfigurer都会一起起作用，我们的配置类也会被调用。

根据源码分析，还可以在自定义配置类中使用如下方式进行配置扩展：

 //所有的WebMvcConfigurerAdapter组件都会一起起作用
 @Bean //将组件注册在容器
 public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){
     WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
         @Override
         public void addViewControllers(ViewControllerRegistry registry) {
             registry.addViewController("/").setViewName("login");
             registry.addViewController("/index.html").setViewName("login");
             registry.addViewController("/main.html").setViewName("dashboard");
         }

         //注册拦截器
         @Override
         public void addInterceptors(InterceptorRegistry registry) {
             //super.addInterceptors(registry);
             //静态资源；  *.css , *.js
             //SpringBoot已经做好了静态资源映射
//                registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
//                        .excludePathPatterns("/index.html","/","/user/login");
         }
     };
     return adapter;
 }

5.2 全面接管SpringMVC

需要在配置类中添加@EnableWebMvc即可,所有的SpringMVC的自动配置都失效了，通常不这么干。

//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
@EnableWebMvc
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
    // super.addViewControllers(registry);
    //浏览器发送 /success 请求来到 success
    registry.addViewController("/success").setViewName("success");
    }
}

为什么添加该注解，就会将SpringBoot对SpringMVC的默认自动配置失效呢？

分析源码如下 ：

① @EnableWebMvc的核心

@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {
    //..
}

② DelegatingWebMvcConfiguration

@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {

    private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();

    @Autowired(required = false)
    public void setConfigurers(List<WebMvcConfigurer> configurers) {
        if (!CollectionUtils.isEmpty(configurers)) {
            this.configurers.addWebMvcConfigurers(configurers);
        }
    }
    //...
}

很眼熟对不对，这货继承自WebMvcConfigurationSupport 。

③ 查看WebMvcAutoConfiguration

@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class,
        WebMvcConfigurerAdapter.class })
//注意这里！！！
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
        ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {

只有在WebMvcConfigurationSupport不存在的情况下，WebMvcAutoConfiguration 才生效！

而@EnableWebMvc将WebMvcConfigurationSupport组件导入进来，但是WebMvcConfigurationSupport只有SpringMVC最基本的功能。

【6】DispatcherServletAutoConfiguration与WebMvcAutoConfiguration

在这两个类中，SpringBoot为我们默认配置了SpringMVC的诸多组件，包括DispatcherServlet等，可以追踪源码进行查看。

DispatcherServletAutoConfiguration 源码如下：

 */
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass(DispatcherServlet.class)
@AutoConfigureAfter(EmbeddedServletContainerAutoConfiguration.class)
public class DispatcherServletAutoConfiguration {

    /*
     * The bean name for a DispatcherServlet that will be mapped to the root URL "/"
     */
    public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";

    /*
     * The bean name for a ServletRegistrationBean for the DispatcherServlet "/"
     */
    public static final String DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME = "dispatcherServletRegistration";

    @Configuration
    @Conditional(DefaultDispatcherServletCondition.class)
    @ConditionalOnClass(ServletRegistration.class)
    @EnableConfigurationProperties(WebMvcProperties.class)
    protected static class DispatcherServletConfiguration {

        private final WebMvcProperties webMvcProperties;

        public DispatcherServletConfiguration(WebMvcProperties webMvcProperties) {
            this.webMvcProperties = webMvcProperties;
        }

        @Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
        public DispatcherServlet dispatcherServlet() {
            DispatcherServlet dispatcherServlet = new DispatcherServlet();
            dispatcherServlet.setDispatchOptionsRequest(
                    this.webMvcProperties.isDispatchOptionsRequest());
            dispatcherServlet.setDispatchTraceRequest(
                    this.webMvcProperties.isDispatchTraceRequest());
            dispatcherServlet.setThrowExceptionIfNoHandlerFound(
                    this.webMvcProperties.isThrowExceptionIfNoHandlerFound());
            return dispatcherServlet;
        }

        @Bean
        @ConditionalOnBean(MultipartResolver.class)
        @ConditionalOnMissingBean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
        public MultipartResolver multipartResolver(MultipartResolver resolver) {
            // Detect if the user has created a MultipartResolver but named it incorrectly
            return resolver;
        }

    }

    @Configuration
    @Conditional(DispatcherServletRegistrationCondition.class)
    @ConditionalOnClass(ServletRegistration.class)
    @EnableConfigurationProperties(WebMvcProperties.class)
    @Import(DispatcherServletConfiguration.class)
    protected static class DispatcherServletRegistrationConfiguration {

        private final ServerProperties serverProperties;

        private final WebMvcProperties webMvcProperties;

        private final MultipartConfigElement multipartConfig;

        public DispatcherServletRegistrationConfiguration(
                ServerProperties serverProperties, WebMvcProperties webMvcProperties,
                ObjectProvider<MultipartConfigElement> multipartConfigProvider) {
            this.serverProperties = serverProperties;
            this.webMvcProperties = webMvcProperties;
            this.multipartConfig = multipartConfigProvider.getIfAvailable();
        }

        @Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
        @ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
        public ServletRegistrationBean dispatcherServletRegistration(
                DispatcherServlet dispatcherServlet) {
            ServletRegistrationBean registration = new ServletRegistrationBean(
                    dispatcherServlet, this.serverProperties.getServletMapping());
            registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
            registration.setLoadOnStartup(
                    this.webMvcProperties.getServlet().getLoadOnStartup());
            if (this.multipartConfig != null) {
                registration.setMultipartConfig(this.multipartConfig);
            }
            return registration;
        }

    }

    @Order(Ordered.LOWEST_PRECEDENCE - 10)
    private static class DefaultDispatcherServletCondition extends SpringBootCondition {

        @Override
        public ConditionOutcome getMatchOutcome(ConditionContext context,
                AnnotatedTypeMetadata metadata) {
            ConditionMessage.Builder message = ConditionMessage
                    .forCondition("Default DispatcherServlet");
            ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
            List<String> dispatchServletBeans = Arrays.asList(beanFactory
                    .getBeanNamesForType(DispatcherServlet.class, false, false));
            if (dispatchServletBeans.contains(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {
                return ConditionOutcome.noMatch(message.found("dispatcher servlet bean")
                        .items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));
            }
            if (beanFactory.containsBean(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {
                return ConditionOutcome
                        .noMatch(message.found("non dispatcher servlet bean")
                                .items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));
            }
            if (dispatchServletBeans.isEmpty()) {
                return ConditionOutcome
                        .match(message.didNotFind("dispatcher servlet beans").atAll());
            }
            return ConditionOutcome.match(message
                    .found("dispatcher servlet bean", "dispatcher servlet beans")
                    .items(Style.QUOTE, dispatchServletBeans)
                    .append("and none is named " + DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));
        }

    }

    @Order(Ordered.LOWEST_PRECEDENCE - 10)
    private static class DispatcherServletRegistrationCondition
            extends SpringBootCondition {

        @Override
        public ConditionOutcome getMatchOutcome(ConditionContext context,
                AnnotatedTypeMetadata metadata) {
            ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
            ConditionOutcome outcome = checkDefaultDispatcherName(beanFactory);
            if (!outcome.isMatch()) {
                return outcome;
            }
            return checkServletRegistration(beanFactory);
        }

        private ConditionOutcome checkDefaultDispatcherName(
                ConfigurableListableBeanFactory beanFactory) {
            List<String> servlets = Arrays.asList(beanFactory
                    .getBeanNamesForType(DispatcherServlet.class, false, false));
            boolean containsDispatcherBean = beanFactory
                    .containsBean(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
            if (containsDispatcherBean
                    && !servlets.contains(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {
                return ConditionOutcome
                        .noMatch(startMessage().found("non dispatcher servlet")
                                .items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));
            }
            return ConditionOutcome.match();
        }

        private ConditionOutcome checkServletRegistration(
                ConfigurableListableBeanFactory beanFactory) {
            ConditionMessage.Builder message = startMessage();
            List<String> registrations = Arrays.asList(beanFactory
                    .getBeanNamesForType(ServletRegistrationBean.class, false, false));
            boolean containsDispatcherRegistrationBean = beanFactory
                    .containsBean(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME);
            if (registrations.isEmpty()) {
                if (containsDispatcherRegistrationBean) {
                    return ConditionOutcome
                            .noMatch(message.found("non servlet registration bean").items(
                                    DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));
                }
                return ConditionOutcome
                        .match(message.didNotFind("servlet registration bean").atAll());
            }
            if (registrations
                    .contains(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)) {
                return ConditionOutcome.noMatch(message.found("servlet registration bean")
                        .items(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));
            }
            if (containsDispatcherRegistrationBean) {
                return ConditionOutcome
                        .noMatch(message.found("non servlet registration bean").items(
                                DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));
            }
            return ConditionOutcome.match(message.found("servlet registration beans")
                    .items(Style.QUOTE, registrations).append("and none is named "
                            + DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));
        }

        private ConditionMessage.Builder startMessage() {
            return ConditionMessage.forCondition("DispatcherServlet Registration");
        }

    }

}

WebMvcAutoConfiguration 源码如下：

@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class,
        WebMvcConfigurerAdapter.class })
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
        ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {

    public static final String DEFAULT_PREFIX = "";

    public static final String DEFAULT_SUFFIX = "";

    @Bean
    @ConditionalOnMissingBean(HiddenHttpMethodFilter.class)
    public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {
        return new OrderedHiddenHttpMethodFilter();
    }

    @Bean
    @ConditionalOnMissingBean(HttpPutFormContentFilter.class)
    @ConditionalOnProperty(prefix = "spring.mvc.formcontent.putfilter", name = "enabled", matchIfMissing = true)
    public OrderedHttpPutFormContentFilter httpPutFormContentFilter() {
        return new OrderedHttpPutFormContentFilter();
    }

    // Defined as a nested config to ensure WebMvcConfigurerAdapter is not read when not
    // on the classpath
    @Configuration
    @Import(EnableWebMvcConfiguration.class)
    @EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })
    public static class WebMvcAutoConfigurationAdapter extends WebMvcConfigurerAdapter {

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

        private final ResourceProperties resourceProperties;

        private final WebMvcProperties mvcProperties;

        private final ListableBeanFactory beanFactory;

        private final HttpMessageConverters messageConverters;

        final ResourceHandlerRegistrationCustomizer resourceHandlerRegistrationCustomizer;

        public WebMvcAutoConfigurationAdapter(ResourceProperties resourceProperties,
                WebMvcProperties mvcProperties, ListableBeanFactory beanFactory,
                @Lazy HttpMessageConverters messageConverters,
                ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider) {
            this.resourceProperties = resourceProperties;
            this.mvcProperties = mvcProperties;
            this.beanFactory = beanFactory;
            this.messageConverters = messageConverters;
            this.resourceHandlerRegistrationCustomizer = resourceHandlerRegistrationCustomizerProvider
                    .getIfAvailable();
        }

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

        @Override
        public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
            Long timeout = this.mvcProperties.getAsync().getRequestTimeout();
            if (timeout != null) {
                configurer.setDefaultTimeout(timeout);
            }
        }

        @Override
        public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
            Map<String, MediaType> mediaTypes = this.mvcProperties.getMediaTypes();
            for (Entry<String, MediaType> mediaType : mediaTypes.entrySet()) {
                configurer.mediaType(mediaType.getKey(), mediaType.getValue());
            }
        }

        @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;
        }

        @Bean
        @ConditionalOnProperty(prefix = "spring.mvc", name = "date-format")
        public Formatter<Date> dateFormatter() {
            return new DateFormatter(this.mvcProperties.getDateFormat());
        }

        @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) {
            for (Converter<?, ?> converter : getBeansOfType(Converter.class)) {
                registry.addConverter(converter);
            }
            for (GenericConverter converter : getBeansOfType(GenericConverter.class)) {
                registry.addConverter(converter);
            }
            for (Formatter<?> formatter : getBeansOfType(Formatter.class)) {
                registry.addFormatter(formatter);
            }
        }

        private <T> Collection<T> getBeansOfType(Class<T> type) {
            return this.beanFactory.getBeansOfType(type).values();
        }

        @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));
            }
        }

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

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

        }

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

        @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);
                mapping.setUrlMap(Collections.singletonMap("**/favicon.ico",
                        faviconRequestHandler()));
                return mapping;
            }

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

        }

    }

    /**
     * Configuration equivalent to {@code @EnableWebMvc}.
     */
    @Configuration
    public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {

        private final WebMvcProperties mvcProperties;

        private final ListableBeanFactory beanFactory;

        private final WebMvcRegistrations mvcRegistrations;

        public EnableWebMvcConfiguration(
                ObjectProvider<WebMvcProperties> mvcPropertiesProvider,
                ObjectProvider<WebMvcRegistrations> mvcRegistrationsProvider,
                ListableBeanFactory beanFactory) {
            this.mvcProperties = mvcPropertiesProvider.getIfAvailable();
            this.mvcRegistrations = mvcRegistrationsProvider.getIfUnique();
            this.beanFactory = beanFactory;
        }

        @Bean
        @Override
        public RequestMappingHandlerAdapter requestMappingHandlerAdapter() {
            RequestMappingHandlerAdapter adapter = super.requestMappingHandlerAdapter();
            adapter.setIgnoreDefaultModelOnRedirect(this.mvcProperties == null ? true
                    : this.mvcProperties.isIgnoreDefaultModelOnRedirect());
            return adapter;
        }

        @Override
        protected RequestMappingHandlerAdapter createRequestMappingHandlerAdapter() {
            if (this.mvcRegistrations != null
                    && this.mvcRegistrations.getRequestMappingHandlerAdapter() != null) {
                return this.mvcRegistrations.getRequestMappingHandlerAdapter();
            }
            return super.createRequestMappingHandlerAdapter();
        }

        @Bean
        @Primary
        @Override
        public RequestMappingHandlerMapping requestMappingHandlerMapping() {
            // Must be @Primary for MvcUriComponentsBuilder to work
            return super.requestMappingHandlerMapping();
        }

        @Bean
        @Override
        public Validator mvcValidator() {
            if (!ClassUtils.isPresent("javax.validation.Validator",
                    getClass().getClassLoader())) {
                return super.mvcValidator();
            }
            return WebMvcValidator.get(getApplicationContext(), getValidator());
        }

        @Override
        protected RequestMappingHandlerMapping createRequestMappingHandlerMapping() {
            if (this.mvcRegistrations != null
                    && this.mvcRegistrations.getRequestMappingHandlerMapping() != null) {
                return this.mvcRegistrations.getRequestMappingHandlerMapping();
            }
            return super.createRequestMappingHandlerMapping();
        }

        @Override
        protected ConfigurableWebBindingInitializer getConfigurableWebBindingInitializer() {
            try {
                return this.beanFactory.getBean(ConfigurableWebBindingInitializer.class);
            }
            catch (NoSuchBeanDefinitionException ex) {
                return super.getConfigurableWebBindingInitializer();
            }
        }

        @Override
        protected ExceptionHandlerExceptionResolver createExceptionHandlerExceptionResolver() {
            if (this.mvcRegistrations != null && this.mvcRegistrations
                    .getExceptionHandlerExceptionResolver() != null) {
                return this.mvcRegistrations.getExceptionHandlerExceptionResolver();
            }
            return super.createExceptionHandlerExceptionResolver();
        }

        @Override
        protected void configureHandlerExceptionResolvers(
                List<HandlerExceptionResolver> exceptionResolvers) {
            super.configureHandlerExceptionResolvers(exceptionResolvers);
            if (exceptionResolvers.isEmpty()) {
                addDefaultHandlerExceptionResolvers(exceptionResolvers);
            }
            if (this.mvcProperties.isLogResolvedException()) {
                for (HandlerExceptionResolver resolver : exceptionResolvers) {
                    if (resolver instanceof AbstractHandlerExceptionResolver) {
                        ((AbstractHandlerExceptionResolver) resolver)
                                .setWarnLogCategory(resolver.getClass().getName());
                    }
                }
            }
        }

        @Bean
        @Override
        public ContentNegotiationManager mvcContentNegotiationManager() {
            ContentNegotiationManager manager = super.mvcContentNegotiationManager();
            List<ContentNegotiationStrategy> strategies = manager.getStrategies();
            ListIterator<ContentNegotiationStrategy> iterator = strategies.listIterator();
            while (iterator.hasNext()) {
                ContentNegotiationStrategy strategy = iterator.next();
                if (strategy instanceof PathExtensionContentNegotiationStrategy) {
                    iterator.set(new OptionalPathExtensionContentNegotiationStrategy(
                            strategy));
                }
            }
            return manager;
        }

    }

    @Configuration
    @ConditionalOnEnabledResourceChain
    static class ResourceChainCustomizerConfiguration {

        @Bean
        public ResourceChainResourceHandlerRegistrationCustomizer resourceHandlerRegistrationCustomizer() {
            return new ResourceChainResourceHandlerRegistrationCustomizer();
        }

    }

    interface ResourceHandlerRegistrationCustomizer {

        void customize(ResourceHandlerRegistration registration);

    }

    private static class ResourceChainResourceHandlerRegistrationCustomizer
            implements ResourceHandlerRegistrationCustomizer {

        @Autowired
        private ResourceProperties resourceProperties = new ResourceProperties();

        @Override
        public void customize(ResourceHandlerRegistration registration) {
            ResourceProperties.Chain properties = this.resourceProperties.getChain();
            configureResourceChain(properties,
                    registration.resourceChain(properties.isCache()));
        }

        private void configureResourceChain(ResourceProperties.Chain properties,
                ResourceChainRegistration chain) {
            Strategy strategy = properties.getStrategy();
            if (strategy.getFixed().isEnabled() || strategy.getContent().isEnabled()) {
                chain.addResolver(getVersionResourceResolver(strategy));
            }
            if (properties.isGzipped()) {
                chain.addResolver(new GzipResourceResolver());
            }
            if (properties.isHtmlApplicationCache()) {
                chain.addTransformer(new AppCacheManifestTransformer());
            }
        }

        private ResourceResolver getVersionResourceResolver(
                ResourceProperties.Strategy properties) {
            VersionResourceResolver resolver = new VersionResourceResolver();
            if (properties.getFixed().isEnabled()) {
                String version = properties.getFixed().getVersion();
                String[] paths = properties.getFixed().getPaths();
                resolver.addFixedVersionStrategy(version, paths);
            }
            if (properties.getContent().isEnabled()) {
                String[] paths = properties.getContent().getPaths();
                resolver.addContentVersionStrategy(paths);
            }
            return resolver;
        }

    }

    static final class WelcomePageHandlerMapping extends AbstractUrlHandlerMapping {

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

        private WelcomePageHandlerMapping(Resource welcomePage,
                String staticPathPattern) {
            if (welcomePage != null && "/**".equals(staticPathPattern)) {
                logger.info("Adding welcome page: " + welcomePage);
                ParameterizableViewController controller = new ParameterizableViewController();
                controller.setViewName("forward:index.html");
                setRootHandler(controller);
                setOrder(0);
            }
        }

        @Override
        public Object getHandlerInternal(HttpServletRequest request) throws Exception {
            for (MediaType mediaType : getAcceptedMediaTypes(request)) {
                if (mediaType.includes(MediaType.TEXT_HTML)) {
                    return super.getHandlerInternal(request);
                }
            }
            return null;
        }

        private List<MediaType> getAcceptedMediaTypes(HttpServletRequest request) {
            String acceptHeader = request.getHeader(HttpHeaders.ACCEPT);
            return MediaType.parseMediaTypes(
                    StringUtils.hasText(acceptHeader) ? acceptHeader : "*/*");
        }

    }

    /**
     * Decorator to make {@link PathExtensionContentNegotiationStrategy} optional
     * depending on a request attribute.
     */
    static class OptionalPathExtensionContentNegotiationStrategy
            implements ContentNegotiationStrategy {

        private static final String SKIP_ATTRIBUTE = PathExtensionContentNegotiationStrategy.class
                .getName() + ".SKIP";

        private final ContentNegotiationStrategy delegate;

        OptionalPathExtensionContentNegotiationStrategy(
                ContentNegotiationStrategy delegate) {
            this.delegate = delegate;
        }

        @Override
        public List<MediaType> resolveMediaTypes(NativeWebRequest webRequest)
                throws HttpMediaTypeNotAcceptableException {
            Object skip = webRequest.getAttribute(SKIP_ATTRIBUTE,
                    RequestAttributes.SCOPE_REQUEST);
            if (skip != null && Boolean.parseBoolean(skip.toString())) {
                return Collections.emptyList();
            }
            return this.delegate.resolveMediaTypes(webRequest);
        }

    }

}