说在前面

本次开始spring-boot-autoconfigure源码解析之DispatcherServletAutoConfiguration

源码解析

@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 将映射到根URL的DispatcherServlet的bean名称"/"    */   public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";   /*    * The bean name for a ServletRegistrationBean for the DispatcherServlet DispatcherServlet的ServletRegistrationBean的bean名称"/"    */   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;      }//    初始化dispatcherServlet      @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;      }//    初始化multipartResolver      @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 检测用户是否创建了一个多部件解析器，但命名不正确         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
    
      multipartConfigProvider) {         this.serverProperties = serverProperties;         this.webMvcProperties = webMvcProperties;         this.multipartConfig = multipartConfigProvider.getIfAvailable();      }//    初始化dispatcherServletRegistration      @Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)      @ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)      public ServletRegistrationBean dispatcherServletRegistration(            DispatcherServlet dispatcherServlet) {//       mapping默认是/*         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();//       根据类型从beanFactory找出DispatcherServlet实现类的beanNames         List
     
       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
      
        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();//       从beanFactory中查找ServletRegistrationBean的实现类的beanNames         List
       
         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");      }   }}
       
      
     
    

说在最后

本次仅代表个人观点，仅供参考。