聊聊springboot2的MappingsEndpoint-白红宇

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();		}	}}复制代码

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());	}	//......}复制代码

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";	}}复制代码

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";	}}复制代码

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(); } //......}复制代码

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(); } //......}复制代码

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

序