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。

如何做自己的服务监控？spring boot 1.x服务监控揭秘

****提供了更多的endpoint管理

ID	Description	Enabled by default
auditevents	Exposes audit events information for the current application.	Yes
beans	Displays a complete list of all the Spring beans in your application.	Yes
caches	Exposes available caches.	Yes
conditions	Shows the conditions that were evaluated on configuration and auto-configuration classes and the reasons why they did or did not match.	Yes
configprops	Displays a collated list of all @ConfigurationProperties.	Yes
env	Exposes properties from Spring’s ConfigurableEnvironment.	Yes
flyway	Shows any Flyway database migrations that have been applied.	Yes
health	Shows application health information.	Yes
httptrace	Displays HTTP trace information (by default, the last 100 HTTP request-response exchanges).	Yes
info	Displays arbitrary application info.	Yes
integrationgraph	Shows the Spring Integration graph.	Yes
loggers	Shows and modifies the configuration of loggers in the application.	Yes
liquibase	Shows any Liquibase database migrations that have been applied.	Yes
metrics	Shows ‘metrics’ information for the current application.	Yes
mappings	Displays a collated list of all @RequestMapping paths.	Yes
scheduledtasks	Displays the scheduled tasks in your application.	Yes
sessions	Allows retrieval and deletion of user sessions from a Spring Session-backed session store. Not available when using Spring Session’s support for reactive web applications.	Yes
shutdown	Lets the application be gracefully shutdown.	No
threaddump	Performs a thread dump.	Yes

If your application is a web application (Spring MVC, Spring WebFlux, or Jersey), you can use the following additional endpoints:

ID	Description	Enabled by default
heapdump	Returns an hprof heap dump file.	Yes
jolokia	Exposes JMX beans over HTTP (when Jolokia is on the classpath, not available for WebFlux).	Yes
logfile	Returns the contents of the logfile (if logging.file or logging.path properties have been set). Supports the use of the HTTP Range header to retrieve part of the log file’s content.	Yes
prometheus	Exposes metrics in a format that can be scraped by a Prometheus server.	Yes

********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@ConditionalOnMissingBeanpublicWebMvcEndpointHandlerMapping 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= newEndpointMapping(webEndpointProperties.getBasePath());return newWebMvcEndpointHandlerMapping(endpointMapping, webEndpoints,endpointMediaTypes, corsProperties.toCorsConfiguration(),newEndpointLinksResolver(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* {@linkReadOperation @ReadOperation}, {@linkWriteOperation @WriteOperation},* {@linkDeleteOperation @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* {@linkFilteredEndpoint filtered} to a certain technology, or provide* {@linkEndpointExtension extension} for the broader endpoint.**@authorAndy Wilkinson*@authorPhillip Webb*@since2.0.0*@seeEndpointExtension*@seeFilteredEndpoint*@seeEndpointDiscoverer*/

使用了@Endpoint注解的类

3.2.2 获取所有的EndPoint

@Overridepublic final Collection<E>getEndpoints() {if (this.endpoints == null) {this.endpoints =discoverEndpoints();}return this.endpoints;}private Collection<E>discoverEndpoints() {Collection<EndpointBean> endpointBeans =createEndpointBeans();addExtensionBeans(endpointBeans);returnconvertToEndpoints(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() + "'");}}returnbyId.values();}privateEndpointBean createEndpointBean(String beanName) {Object bean= this.applicationContext.getBean(beanName);return newEndpointBean(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

    privateRequestMappingInfo 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.RequestMappingHandlerMappingorg.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 {@codeWebMvcEndpointHandlerMapping} instance that provides mappings* for the given endpoints.*@paramendpointMapping the base mapping for all endpoints*@paramendpoints the web endpoints*@paramendpointMediaTypes media types consumed and produced by the endpoints*@paramcorsConfiguration the CORS configuration for the endpoints or {@codenull}*@paramlinksResolver resolver for determining links to available endpoints*/publicWebMvcEndpointHandlerMapping(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()

@Overrideprotected voidinitHandlerMethods() {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 voidregisterMappingForOperation(ExposableWebEndpoint endpoint,WebOperation operation) {ServletWebOperation servletWebOperation=wrapServletWebOperation(endpoint,operation,newServletWebOperationAdapter(operation));registerMapping(createRequestMappingInfo(operation),new OperationHandler(servletWebOperation), this.handleMethod);}/*** Hook point that allows subclasses to wrap the {@linkServletWebOperation} before* it's called. Allows additional features, such as security, to be added.*@paramendpoint the source endpoint*@paramoperation the source operation*@paramservletWebOperation the servlet web operation to wrap*@returna wrapped servlet web operation*/protectedServletWebOperation wrapServletWebOperation(ExposableWebEndpoint endpoint,WebOperation operation, ServletWebOperation servletWebOperation) {returnservletWebOperation;}privateRequestMappingInfo createRequestMappingInfo(WebOperation operation) {WebOperationRequestPredicate predicate=operation.getRequestPredicate();PatternsRequestCondition patterns=patternsRequestConditionForPattern(predicate.getPath());RequestMethodsRequestCondition methods= newRequestMethodsRequestCondition(RequestMethod.valueOf(predicate.getHttpMethod().name()));ConsumesRequestCondition consumes= newConsumesRequestCondition(StringUtils.toStringArray(predicate.getConsumes()));ProducesRequestCondition produces= newProducesRequestCondition(StringUtils.toStringArray(predicate.getProduces()));return new RequestMappingInfo(null, patterns, methods, null, null, consumes,produces,null);}

3.3.2 获取ServletWebOperationAdapter

AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle

@OverridepublicObject handle(HttpServletRequest request,@RequestBody(required= false) Map<String, String>body) {Map<String, Object> arguments =getArguments(request, body);try{returnhandleResult(this.operation.invoke(newInvocationContext(newServletSecurityContext(request), arguments)),HttpMethod.valueOf(request.getMethod()));}catch(InvalidEndpointRequestException ex) {throw newBadOperationRequestException(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

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

调用 @ReadOperation, @WriteOperation, or @DeleteOperation方法

    private void addOperations(MultiValueMap<OperationKey, O>indexed, EndpointId id,Object target,booleanreplaceLast) {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 finalParameterValueMapper 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) {returnMethodIntrospector.selectMethods(target.getClass(),(MetadataLookup<O>) (method) ->createOperation(id, target, method)).values();}privateO createOperation(EndpointId endpointId, Object target, Method method) {returnOPERATION_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