"

Actuator是spring boot项目中非常强大一个功能，有助于对应用程序进行监视和管理，通过 restful api请求来监管、审计、收集应用的运行情况，针对微服务而言它是必不可少的一个环节。

spring 2.x actuator相对于spring 1.x actuator做了较大的改变。

****提供了更多的endpoint管理《略》

********更多的metrics

• JVM metrics, report utilization of:
• Various memory and buffer pools
• Statistics related to garbage collection
• Threads utilization
• Number of classes loaded/unloaded
• CPU metrics
• File descriptor metrics
• Kafka consumer metrics
• Log4j2 metrics: record the number of events logged to Log4j2 at each level
• Logback metrics: record the number of events logged to Logback at each level
• Uptime metrics: report a gauge for uptime and a fixed gauge representing the application’s absolute start time
• Tomcat metrics
• Spring Integration metrics

*********内部实现也发生了较大的变化，使用micrometer第三方工具来完成metric的实现。下面我们就亲自看看吧！

1.准备源码

https://github.com/tjanusz-personal/springbootrestdemo/tree/master/src/main/java/com/demo/springbootrestdemo

2.导入并启动项目

( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/ ___)| |_)| | | | | || (_| | ) ) ) )
 ' |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot :: (v2.0.4.RELEASE)
2019-01-17 11:20:39.076 INFO 5180 --- [ main] c.d.s.SpringbootrestdemoApplication : Starting SpringbootrestdemoApplication on DESKTOP-405G2C8 with PID 5180 (E:\document\springbootrestdemo\build\classes\java\main started by dell in E:\document\springbootrestdemo)
2019-01-17 11:20:39.080 INFO 5180 --- [ main] c.d.s.SpringbootrestdemoApplication : No active profile set, falling back to default profiles: default
2019-01-17 11:20:39.147 INFO 5180 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6f01b95f: startup date [Thu Jan 17 11:20:39 CST 2019]; root of context hierarchy
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.springframework.cglib.core.ReflectUtils$1 (file:/D:/gradle/caches/modules-2/files-2.1/org.springframework/spring-core/5.0.8.RELEASE/dc39c49e3246cdf73d3786ac41119140aed3fa08/spring-core-5.0.8.RELEASE.jar) to method java.lang.ClassLoader.defineClass(java.lang.Stri
ng,byte[],int,int,java.security.ProtectionDomain)
WARNING: Please consider reporting this to the maintainers of org.springframework.cglib.core.ReflectUtils$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
2019-01-17 11:20:40.341 INFO 5180 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.hateoas.config.HateoasConfiguration' of type [org.springframework.hateoas.config.HateoasConfiguration$$EnhancerBySpringCGLIB$$ecf2a812] is not eligible for getting processed by a
ll BeanPostProcessors (for example: not eligible for auto-proxying)
2019-01-17 11:20:40.982 INFO 5180 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2019-01-17 11:20:41.015 INFO 5180 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2019-01-17 11:20:41.016 INFO 5180 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.32
2019-01-17 11:20:41.029 INFO 5180 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [D:\software\jdk11\bin;C:\Windows\Sun\Java\bin;C:\Windows\sys
tem32;C:\Windows;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;D:\software\jdk11\bin;D:\software\TortoiseGit\bin;D:\software\Git\cmd;D:\software\apache-maven-3.5.4\bin;D:\software\gradle-4.10.2\bin;D:\software\go\bin;D:\s
oftware\ant\bin;D:\software\anaconda;D:\software\anaconda\Scripts;D:\software\anaconda\Library\bin;C:\Users\dell\AppData\Local\Microsoft\WindowsApps;;.]
2019-01-17 11:20:41.162 INFO 5180 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2019-01-17 11:20:41.168 INFO 5180 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2035 ms
2019-01-17 11:20:41.832 INFO 5180 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2019-01-17 11:20:41.832 INFO 5180 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'webMvcMetricsFilter' to: [/*]
2019-01-17 11:20:41.832 INFO 5180 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpTraceFilter' to: [/*]
2019-01-17 11:20:41.833 INFO 5180 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/]
2019-01-17 11:20:41.960 INFO 5180 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped \"{[/saveUrl],methods=[POST],consumes=[application/json;charset=UTF-8 || application/x-www-form-urlencoded],produces=[application/json;charset=UTF-8 || application/xml]}\" onto public com.demo.spring
bootrestdemo.domain.response.SaveUrlResponse com.demo.springbootrestdemo.web.DemoController.saveUrl(com.demo.springbootrestdemo.domain.request.SaveUrlRequest,java.lang.String,java.lang.String)
2019-01-17 11:20:41.961 INFO 5180 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped \"{[/alive],methods=[GET]}\" onto public com.demo.springbootrestdemo.domain.response.DemoPingResponse com.demo.springbootrestdemo.web.DemoController.alive()
2019-01-17 11:20:41.964 INFO 5180 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped \"{[/error],produces=[text/html]}\" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http
.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2019-01-17 11:20:41.964 INFO 5180 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped \"{[/error]}\" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.err
or(javax.servlet.http.HttpServletRequest)
2019-01-17 11:20:42.038 INFO 5180 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6f01b95f: startup date [Thu Jan 17 11:20:39 CST 2019]; root of context hierar
chy
2019-01-17 11:20:42.087 INFO 5180 --- [ main] .m.m.a.ExceptionHandlerExceptionResolver : Detected @ExceptionHandler methods in restResponseEntityExceptionHandler
2019-01-17 11:20:42.529 INFO 5180 --- [ main] o.s.b.a.e.web.EndpointLinksResolver : Exposing 14 endpoint(s) beneath base path '/actuator'
2019-01-17 11:20:42.538 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/auditevents],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.serv
let.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.539 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/beans],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.Ab
stractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.539 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/health],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.A
bstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.540 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/conditions],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servl
et.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.540 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/configprops],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.serv
let.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.540 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/env/{toMatch}],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.se
rvlet.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.541 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/env],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.Abst
ractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.541 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/info],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.Abs
tractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.541 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/loggers/{name}],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.s
ervlet.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.542 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/loggers/{name}],methods=[POST],consumes=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.
servlet.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.542 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/loggers],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.
AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.543 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/heapdump],methods=[GET],produces=[application/octet-stream]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.AbstractWebMvcEndpointHandlerMapping$Op
erationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.543 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/threaddump],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servl
et.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.543 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/metrics],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.
AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.544 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/metrics/{requiredMetricName}],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.
endpoint.web.servlet.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.544 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/scheduledtasks],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.s
ervlet.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.544 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/httptrace],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servle
t.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.545 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator/mappings],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet
.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2019-01-17 11:20:42.546 INFO 5180 --- [ main] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped \"{[/actuator],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}\" onto protected java.util.Map<java.lang.String, java.util.Map<java.lang.String, org.springfr
amework.boot.actuate.endpoint.web.Link>> org.springframework.boot.actuate.endpoint.web.servlet.WebMvcEndpointHandlerMapping.links(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2019-01-17 11:20:42.590 INFO 5180 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2019-01-17 11:20:42.641 INFO 5180 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2019-01-17 11:20:42.648 INFO 5180 --- [ main] c.d.s.SpringbootrestdemoApplication : Started SpringbootrestdemoApplication in 4.008 seconds (JVM running for 4.517)
<=========----> 75% EXECUTING [25s]
> :bootRun

3.获取EndPoint

3.0 来源

 \"webEndpointServletHandlerMapping\": {
 \"aliases\": [
 
 ],
 \"scope\": \"singleton\",
 \"type\": \"org.springframework.boot.actuate.endpoint.web.servlet.WebMvcEndpointHandlerMapping\",
 \"resource\": \"class path resource [org/springframework/boot/actuate/autoconfigure/endpoint/web/servlet/WebMvcEndpointManagementContextConfiguration.class]\",
 \"dependencies\": [
 \"webEndpointDiscoverer\",
 \"servletEndpointDiscoverer\",
 \"controllerEndpointDiscoverer\",
 \"endpointMediaTypes\",
 \"management.endpoints.web.cors-org.springframework.boot.actuate.autoconfigure.endpoint.web.CorsEndpointProperties\",
 \"management.endpoints.web-org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties\"
 ]
 }

spring.factories定义了

org.springframework.boot.actuate.autoconfigure.web.ManagementContextConfiguration=\
org.springframework.boot.actuate.autoconfigure.endpoint.web.ServletEndpointManagementContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.endpoint.web.reactive.WebFluxEndpointManagementContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.endpoint.web.servlet.WebMvcEndpointManagementContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.endpoint.web.jersey.JerseyWebEndpointManagementContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.web.jersey.JerseyManagementChildContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.web.reactive.ReactiveManagementChildContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.web.servlet.ServletManagementChildContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.web.servlet.WebMvcEndpointChildContextConfiguration

3.1 映射

 @Bean
 @ConditionalOnMissingBean
 public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(
 WebEndpointsSupplier webEndpointsSupplier,
 ServletEndpointsSupplier servletEndpointsSupplier,
 ControllerEndpointsSupplier controllerEndpointsSupplier,
 EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties,
 WebEndpointProperties webEndpointProperties) {
 List<ExposableEndpoint<?>> allEndpoints = new ArrayList<>();
 Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier
 .getEndpoints();
 allEndpoints.addAll(webEndpoints);
 allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
 allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
 EndpointMapping endpointMapping = new EndpointMapping(
 webEndpointProperties.getBasePath());
 return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints,
 endpointMediaTypes, corsProperties.toCorsConfiguration(),
 new EndpointLinksResolver(allEndpoints,
 webEndpointProperties.getBasePath()));
 }

3.2 获取EndPoint

3.2.1 EndPoint定义

/**
 * Identifies a type as being an actuator endpoint that provides information about the
 * running application. Endpoints can be exposed over a variety of technologies including
 * JMX and HTTP.
 * <p>
 * Most {@code @Endpoint} classes will declare one or more
 * {@link ReadOperation @ReadOperation}, {@link WriteOperation @WriteOperation},
 * {@link DeleteOperation @DeleteOperation} annotated methods which will be automatically
 * adapted to the exposing technology (JMX, Spring MVC, Spring WebFlux, Jersey etc.).
 * <p>
 * {@code @Endpoint} represents the lowest common denominator for endpoints and
 * intentionally limits the sorts of operation methods that may be defined in order to
 * support the broadest possible range of exposure technologies. If you need deeper
 * support for a specific technology you can either write an endpoint that is
 * {@link FilteredEndpoint filtered} to a certain technology, or provide
 * {@link EndpointExtension extension} for the broader endpoint.
 *
 * @author Andy Wilkinson
 * @author Phillip Webb
 * @since 2.0.0
 * @see EndpointExtension
 * @see FilteredEndpoint
 * @see EndpointDiscoverer
 */

使用了@Endpoint注解的类

3.2.2 获取所有的EndPoint

 @Override
 public final Collection<E> getEndpoints() {
 if (this.endpoints == null) {
 this.endpoints = discoverEndpoints();
 }
 return this.endpoints;
 }
 private Collection<E> discoverEndpoints() {
 Collection<EndpointBean> endpointBeans = createEndpointBeans();
 addExtensionBeans(endpointBeans);
 return convertToEndpoints(endpointBeans);
 }
 private Collection<EndpointBean> createEndpointBeans() {
 Map<EndpointId, EndpointBean> byId = new LinkedHashMap<>();
 String[] beanNames = BeanFactoryUtils.beanNamesForAnnotationIncludingAncestors(
 this.applicationContext, Endpoint.class);
 for (String beanName : beanNames) {
 if (!ScopedProxyUtils.isScopedTarget(beanName)) {
 EndpointBean endpointBean = createEndpointBean(beanName);
 EndpointBean previous = byId.putIfAbsent(endpointBean.getId(),
 endpointBean);
 Assert.state(previous == null,
 () -> \"Found two endpoints with the id '\" + endpointBean.getId()
 + \"': '\" + endpointBean.getBeanName() + \"' and '\"
 + previous.getBeanName() + \"'\");
 }
 }
 return byId.values();
 }
 private EndpointBean createEndpointBean(String beanName) {
 Object bean = this.applicationContext.getBean(beanName);
 return new EndpointBean(beanName, bean);
 }
 private void addExtensionBeans(Collection<EndpointBean> endpointBeans) {
 Map<EndpointId, EndpointBean> byId = endpointBeans.stream()
 .collect(Collectors.toMap(EndpointBean::getId, Function.identity()));
 String[] beanNames = BeanFactoryUtils.beanNamesForAnnotationIncludingAncestors(
 this.applicationContext, EndpointExtension.class);
 for (String beanName : beanNames) {
 ExtensionBean extensionBean = createExtensionBean(beanName);
 EndpointBean endpointBean = byId.get(extensionBean.getEndpointId());
 Assert.state(endpointBean != null,
 () -> (\"Invalid extension '\" + extensionBean.getBeanName()
 + \"': no endpoint found with id '\"
 + extensionBean.getEndpointId() + \"'\"));
 addExtensionBean(endpointBean, extensionBean);
 }
 }

3.3 WebMvcEndpointHandlerMapping

3.3.0 spring mvc的流程复习

其中：

第2步获取HandlerMapping，其层次结构

其中RequestMappingHandlerMapping用来处理@RequestMapping注解

 private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
 RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class);
 RequestCondition<?> condition = (element instanceof Class ?
 getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element));
 return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null);
 }

第3步获取HandlerAdapter，其层次结构

默认handlerMapping和handlerAdapter定义在DispatcherServlet.properties

org.springframework.web.servlet.HandlerMapping=org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,\
 org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping
org.springframework.web.servlet.HandlerAdapter=org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,\
 org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,\
 org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter

3.3.1 获取WebMvcEndpointHandlerMapping

 /**
 * Creates a new {@code WebMvcEndpointHandlerMapping} instance that provides mappings
 * for the given endpoints.
 * @param endpointMapping the base mapping for all endpoints
 * @param endpoints the web endpoints
 * @param endpointMediaTypes media types consumed and produced by the endpoints
 * @param corsConfiguration the CORS configuration for the endpoints or {@code null}
 * @param linksResolver resolver for determining links to available endpoints
 */
 public WebMvcEndpointHandlerMapping(EndpointMapping endpointMapping,
 Collection<ExposableWebEndpoint> endpoints,
 EndpointMediaTypes endpointMediaTypes, CorsConfiguration corsConfiguration,
 EndpointLinksResolver linksResolver) {
 super(endpointMapping, endpoints, endpointMediaTypes, corsConfiguration);
 this.linksResolver = linksResolver;
 setOrder(-100);
 }

父类实现了initHandlerMethods()

 @Override
 protected void initHandlerMethods() {
 for (ExposableWebEndpoint endpoint : this.endpoints) {
 for (WebOperation operation : endpoint.getOperations()) {
 registerMappingForOperation(endpoint, operation);
 }
 }
 if (StringUtils.hasText(this.endpointMapping.getPath())) {
 registerLinksMapping();
 }
 }

将endpoint的Operation映射到Method级别，类似于@RequestMapping

 private void registerMappingForOperation(ExposableWebEndpoint endpoint,
 WebOperation operation) {
 ServletWebOperation servletWebOperation = wrapServletWebOperation(endpoint,
 operation, new ServletWebOperationAdapter(operation));
 registerMapping(createRequestMappingInfo(operation),
 new OperationHandler(servletWebOperation), this.handleMethod);
 }
 /**
 * Hook point that allows subclasses to wrap the {@link ServletWebOperation} before
 * it's called. Allows additional features, such as security, to be added.
 * @param endpoint the source endpoint
 * @param operation the source operation
 * @param servletWebOperation the servlet web operation to wrap
 * @return a wrapped servlet web operation
 */
 protected ServletWebOperation wrapServletWebOperation(ExposableWebEndpoint endpoint,
 WebOperation operation, ServletWebOperation servletWebOperation) {
 return servletWebOperation;
 }
 private RequestMappingInfo createRequestMappingInfo(WebOperation operation) {
 WebOperationRequestPredicate predicate = operation.getRequestPredicate();
 PatternsRequestCondition patterns = patternsRequestConditionForPattern(
 predicate.getPath());
 RequestMethodsRequestCondition methods = new RequestMethodsRequestCondition(
 RequestMethod.valueOf(predicate.getHttpMethod().name()));
 ConsumesRequestCondition consumes = new ConsumesRequestCondition(
 StringUtils.toStringArray(predicate.getConsumes()));
 ProducesRequestCondition produces = new ProducesRequestCondition(
 StringUtils.toStringArray(predicate.getProduces()));
 return new RequestMappingInfo(null, patterns, methods, null, null, consumes,
 produces, null);
 }

3.3.2 获取ServletWebOperationAdapter

AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle

 @Override
 public Object handle(HttpServletRequest request,
 @RequestBody(required = false) Map<String, String> body) {
 Map<String, Object> arguments = getArguments(request, body);
 try {
 return handleResult(
 this.operation.invoke(new InvocationContext(
 new ServletSecurityContext(request), arguments)),
 HttpMethod.valueOf(request.getMethod()));
 }
 catch (InvalidEndpointRequestException ex) {
 throw new BadOperationRequestException(ex.getReason());
 }
 }

4.触发机制

If you add a @Bean annotated with @Endpoint, any methods annotated with @ReadOperation, @WriteOperation, or @DeleteOperation are automatically exposed over JMX and, in a web application, over HTTP as well. Endpoints can be exposed over HTTP using Jersey, Spring MVC, or Spring WebFlux.

if you need access to web-framework-specific functionality, you can implement Servlet or Spring @Controller and @RestController endpoints at the cost of them not being available over JMX or when using a different web framework.

EndpointDiscoverer

 @Override
 public final Collection<E> getEndpoints() {
 if (this.endpoints == null) {
 this.endpoints = discoverEndpoints();
 }
 return this.endpoints;
 }
 private Collection<E> discoverEndpoints() {
 Collection<EndpointBean> endpointBeans = createEndpointBeans();
 addExtensionBeans(endpointBeans);
 return convertToEndpoints(endpointBeans);
 }

调用 @ReadOperation, @WriteOperation, or @DeleteOperation方法

 private void addOperations(MultiValueMap<OperationKey, O> indexed, EndpointId id,
 Object target, boolean replaceLast) {
 Set<OperationKey> replacedLast = new HashSet<>();
 Collection<O> operations = this.operationsFactory.createOperations(id, target);
 for (O operation : operations) {
 OperationKey key = createOperationKey(operation);
 O last = getLast(indexed.get(key));
 if (replaceLast && replacedLast.add(key) && last != null) {
 indexed.get(key).remove(last);
 }
 indexed.add(key, operation);
 }
 }

其中DiscoveredOperationsFactory定义了@ReadOperation, @WriteOperation, or @DeleteOperation方法

 private static final Map<OperationType, Class<? extends Annotation>> OPERATION_TYPES;
 static {
 Map<OperationType, Class<? extends Annotation>> operationTypes = new EnumMap<>(
 OperationType.class);
 operationTypes.put(OperationType.READ, ReadOperation.class);
 operationTypes.put(OperationType.WRITE, WriteOperation.class);
 operationTypes.put(OperationType.DELETE, DeleteOperation.class);
 OPERATION_TYPES = Collections.unmodifiableMap(operationTypes);
 }
 private final ParameterValueMapper parameterValueMapper;
 private final Collection<OperationInvokerAdvisor> invokerAdvisors;
 DiscoveredOperationsFactory(ParameterValueMapper parameterValueMapper,
 Collection<OperationInvokerAdvisor> invokerAdvisors) {
 this.parameterValueMapper = parameterValueMapper;
 this.invokerAdvisors = invokerAdvisors;
 }
 public Collection<O> createOperations(EndpointId id, Object target) {
 return MethodIntrospector.selectMethods(target.getClass(),
 (MetadataLookup<O>) (method) -> createOperation(id, target, method))
 .values();
 }
 private O createOperation(EndpointId endpointId, Object target, Method method) {
 return OPERATION_TYPES.entrySet().stream()
 .map((entry) -> createOperation(endpointId, target, method,
 entry.getKey(), entry.getValue()))
 .filter(Objects::nonNull).findFirst().orElse(null);
 }

总结：

1.若一个Bean在类上使用@Endpoint注解，并且在方法上使用@ReadOperation, @WriteOperation, or @DeleteOperation注解，那么自动可以使用jmx或者http访问，http提供服务的可以是Jersey, Spring MVC或者Spring WebFlux.

2.http提供服务的基本机制

2.1 使用HandlerMapping映射请求
2.2 使用HandlerAdapter(自定义)聚合EndPoint，并代理EndPoint的请求。

参考文献

【1】https://terasolunaorg.github.io/guideline/1.0.x/en/Overview/SpringMVCOverview.html

【2】https://docs.spring.io/spring-boot/docs/2.1.2.RELEASE/reference/htmlsingle/#production-ready-enabling

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