序

本文主要研究下springboot2的MappingsEndpoint

MappingsEndpointAutoConfiguration

spring-boot-actuator-autoconfigure-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/autoconfigure/web/mappings/MappingsEndpointAutoConfiguration.java

@ManagementContextConfigurationpublic class MappingsEndpointAutoConfiguration {    @Bean    @ConditionalOnEnabledEndpoint    public MappingsEndpoint mappingsEndpoint(ApplicationContext applicationContext,            ObjectProvider
    
     
      > descriptionProviders) {        return new MappingsEndpoint(                descriptionProviders.getIfAvailable(Collections::emptyList),                applicationContext);    }    @Configuration    @ConditionalOnWebApplication(type = Type.SERVLET)    static class ServletWebConfiguration {        @Bean        ServletsMappingDescriptionProvider servletMappingDescriptionProvider() {            return new ServletsMappingDescriptionProvider();        }        @Bean        FiltersMappingDescriptionProvider filterMappingDescriptionProvider() {            return new FiltersMappingDescriptionProvider();        }        @Configuration        @ConditionalOnClass(DispatcherServlet.class)        @ConditionalOnBean(DispatcherServlet.class)        static class SpringMvcConfiguration {            @Bean            DispatcherServletsMappingDescriptionProvider dispatcherServletMappingDescriptionProvider() {                return new DispatcherServletsMappingDescriptionProvider();            }        }    }    @Configuration    @ConditionalOnWebApplication(type = Type.REACTIVE)    @ConditionalOnClass(DispatcherHandler.class)    @ConditionalOnBean(DispatcherHandler.class)    static class ReactiveWebConfiguration {        @Bean        public DispatcherHandlersMappingDescriptionProvider dispatcherHandlerMappingDescriptionProvider(                ApplicationContext applicationContext) {            return new DispatcherHandlersMappingDescriptionProvider();        }    }}
     
    

这里使用descriptionProviders创建mappingsEndpoint，然后根据是servlet或reactive的方式来创建不同的MappingDescriptionProvider，servlet创建的是ServletsMappingDescriptionProvider，FiltersMappingDescriptionProvider，DispatcherServletsMappingDescriptionProvider，reactive创建的是DispatcherHandlersMappingDescriptionProvider

MappingsEndpoint

spring-boot-actuator-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/web/mappings/MappingsEndpoint.java

@Endpoint(id = "mappings")public class MappingsEndpoint {    private final Collection
    
      descriptionProviders;    private final ApplicationContext context;    public MappingsEndpoint(Collection
     
       descriptionProviders,            ApplicationContext context) {        this.descriptionProviders = descriptionProviders;        this.context = context;    }    @ReadOperation    public ApplicationMappings mappings() {        ApplicationContext target = this.context;        Map
      
        contextMappings = new HashMap<>();        while (target != null) {            contextMappings.put(target.getId(), mappingsForContext(target));            target = target.getParent();        }        return new ApplicationMappings(contextMappings);    }    private ContextMappings mappingsForContext(ApplicationContext applicationContext) {        Map
       
         mappings = new HashMap<>();        this.descriptionProviders                .forEach((provider) -> mappings.put(provider.getMappingName(),                        provider.describeMappings(applicationContext)));        return new ContextMappings(mappings, applicationContext.getParent() == null ? null                : applicationContext.getId());    }    //......}
       
      
     
    

这里根据descriptionProviders创建ContextMappings

servlet方式

ServletsMappingDescriptionProvider

spring-boot-actuator-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/web/mappings/servlet/ServletsMappingDescriptionProvider.java

public class ServletsMappingDescriptionProvider implements MappingDescriptionProvider {    @Override    public List
    
      describeMappings(            ApplicationContext context) {        if (!(context instanceof WebApplicationContext)) {            return Collections.emptyList();        }        return ((WebApplicationContext) context).getServletContext()                .getServletRegistrations().values().stream()                .map(ServletRegistrationMappingDescription::new)                .collect(Collectors.toList());    }    @Override    public String getMappingName() {        return "servlets";    }}
    

这里从servletContext中获取ServletRegistrations，再获取ServletRegistrationMappingDescription

FiltersMappingDescriptionProvider

spring-boot-actuator-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/web/mappings/servlet/FiltersMappingDescriptionProvider.java

public class FiltersMappingDescriptionProvider implements MappingDescriptionProvider {    @Override    public List
    
      describeMappings(            ApplicationContext context) {        if (!(context instanceof WebApplicationContext)) {            return Collections.emptyList();        }        return ((WebApplicationContext) context).getServletContext()                .getFilterRegistrations().values().stream()                .map(FilterRegistrationMappingDescription::new)                .collect(Collectors.toList());    }    @Override    public String getMappingName() {        return "servletFilters";    }}
    

这里从servletContext中获取FilterRegistrations，再获取FilterRegistrationMappingDescription

DispatcherServletsMappingDescriptionProvider

spring-boot-actuator-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/web/mappings/servlet/DispatcherServletsMappingDescriptionProvider.java

public class DispatcherServletsMappingDescriptionProvider        implements MappingDescriptionProvider {    private static final List
    
     > descriptionProviders;    static {        List
     
      > providers = new ArrayList<>();        providers.add(new RequestMappingInfoHandlerMappingDescriptionProvider());        providers.add(new UrlHandlerMappingDescriptionProvider());        if (ClassUtils.isPresent(                "org.springframework.data.rest.webmvc.support.DelegatingHandlerMapping",                null)) {            providers.add(new DelegatingHandlerMappingDescriptionProvider(                    new ArrayList<>(providers)));        }        descriptionProviders = Collections.unmodifiableList(providers);    }    @Override    public String getMappingName() {        return "dispatcherServlets";    }    @Override    public Map
      
       > describeMappings(            ApplicationContext context) {        if (context instanceof WebApplicationContext) {            return describeMappings((WebApplicationContext) context);        }        return Collections.emptyMap();    }    private Map
       
        > describeMappings(            WebApplicationContext context) {        Map
        
         > mappings = new HashMap<>();        context.getBeansOfType(DispatcherServlet.class)                .forEach((name, dispatcherServlet) -> mappings.put(name,                        describeMappings(new DispatcherServletHandlerMappings(name,                                dispatcherServlet, context))));        return mappings;    }    private List
         
           describeMappings( DispatcherServletHandlerMappings mappings) { return mappings.getHandlerMappings().stream().flatMap(this::describe) .collect(Collectors.toList()); } private 
          
            Stream
           
             describe( T handlerMapping) { return describe(handlerMapping, descriptionProviders).stream(); } @SuppressWarnings("unchecked") private static 
            
              List
             
               describe( T handlerMapping, List
              
               > descriptionProviders) { for (HandlerMappingDescriptionProvider
                descriptionProvider : descriptionProviders) { if (descriptionProvider.getMappingClass().isInstance(handlerMapping)) { return ((HandlerMappingDescriptionProvider
               
                ) descriptionProvider) .describe(handlerMapping); } } return Collections.emptyList(); } //......}
               
              
             
            
           
          
         
        
       
      
     
    

这里主要从DelegatingHandlerMappingDescriptionProvider、RequestMappingInfoHandlerMappingDescriptionProvider、UrlHandlerMappingDescriptionProvider获取DispatcherServletMappingDescription

reactive方式

DispatcherHandlersMappingDescriptionProvider

spring-boot-actuator-2.0.1.RELEASE-sources.jar!/org/springframework/boot/actuate/web/mappings/reactive/DispatcherHandlersMappingDescriptionProvider.java

public class DispatcherHandlersMappingDescriptionProvider        implements MappingDescriptionProvider {    private static final List
    
     > descriptionProviders = Arrays            .asList(new RequestMappingInfoHandlerMappingDescriptionProvider(),                    new UrlHandlerMappingDescriptionProvider(),                    new RouterFunctionMappingDescriptionProvider());    @Override    public String getMappingName() {        return "dispatcherHandlers";    }    @Override    public Map
     
      > describeMappings(            ApplicationContext context) {        Map
      
       > mappings = new HashMap<>();        context.getBeansOfType(DispatcherHandler.class).forEach(                (name, handler) -> mappings.put(name, describeMappings(handler)));        return mappings;    }    private List
       
         describeMappings(            DispatcherHandler dispatcherHandler) {        return dispatcherHandler.getHandlerMappings().stream().flatMap(this::describe)                .collect(Collectors.toList());    }    @SuppressWarnings("unchecked")    private 
        
          Stream
         
           describe( T handlerMapping) { for (HandlerMappingDescriptionProvider
           descriptionProvider : descriptionProviders) { if (descriptionProvider.getMappingClass().isInstance(handlerMapping)) { return ((HandlerMappingDescriptionProvider
          
           ) descriptionProvider) .describe(handlerMapping).stream(); } } return Stream.empty(); } //......}
          
         
        
       
      
     
    

与servlet获取DispatcherServletsMappingDescriptionProvider不同，reactive获取的是DispatcherHandlersMappingDescriptionProvider

主要从RequestMappingInfoHandlerMappingDescriptionProvider、RouterFunctionMappingDescriptionProvider、UrlHandlerMappingDescriptionProvider这三个来获取HandlerMappingDescriptionProvider

小结

springboot2的MappingsEndpoint通过provider根据servlet及reactive分别进行各自的mappings获取，servlet主要分为ServletsMappingDescriptionProvider、FiltersMappingDescriptionProvider、DispatcherServletsMappingDescriptionProvider，而reactive主要分为DispatcherHandlersMappingDescriptionProvider

doc