添加依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
 </dependency>

接口暴露模式

management.contextPath=/actuator
#取消鉴权模式
management.security.enabled=false

即所有actuator相关的接口都需要添加/actuator前缀

查看暴露的接口

http://localhost:8080/actuator/mappings

打开网页后搜索: /actuator/

actuator源码解析

先看下actuator是如何实现的,以beans为例子

/beans请求是哪个spring-bean在处理（endpointHandlerMapping）

http://localhost:8080/actuator/mappings

{
[/actuator/beans || /actuator/beans.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v1+json || application/json]}: {
bean: "endpointHandlerMapping",
method: "public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()"
}

访问mappings接口，可以看到 /beans的处理类是endpointHandlerMapping

endpointHandlerMapping对应的类是哪个

http://localhost:8080/actuator/beans

{
bean: "endpointHandlerMapping",
aliases: [ ],
scope: "singleton",
type: "org.springframework.boot.actuate.endpoint.mvc.EndpointHandlerMapping",
resource: "class path resource [org/springframework/boot/actuate/autoconfigure/EndpointWebMvcManagementContextConfiguration.class]",
dependencies: [
"mvcEndpoints"
]
}

endpointHandlerMapping对应的类为org.springframework.boot.actuate.endpoint.mvc.EndpointHandlerMapping，初始化的configuration类为org/springframework/boot/actuate/autoconfigure/EndpointWebMvcManagementContextConfiguration.class。

EndpointWebMvcManagementContextConfiguration的初始化过程

    @Bean
    @ConditionalOnMissingBean
    public EndpointHandlerMapping endpointHandlerMapping() {
        Set<MvcEndpoint> endpoints = mvcEndpoints().getEndpoints();
        CorsConfiguration corsConfiguration = getCorsConfiguration(this.corsProperties);
        EndpointHandlerMapping mapping = new EndpointHandlerMapping(endpoints,
                corsConfiguration);
        mapping.setPrefix(this.managementServerProperties.getContextPath());
        MvcEndpointSecurityInterceptor securityInterceptor = new MvcEndpointSecurityInterceptor(
                this.managementServerProperties.getSecurity().isEnabled(),
                this.managementServerProperties.getSecurity().getRoles());
        mapping.setSecurityInterceptor(securityInterceptor);
        for (EndpointHandlerMappingCustomizer customizer : this.mappingCustomizers) {
            customizer.customize(mapping);
        }
        return mapping;
}

    @Bean
    @ConditionalOnMissingBean
    public MvcEndpoints mvcEndpoints() {
        return new MvcEndpoints();
    }

EndpointHandlerMapping的父类为RequestMappingHandlerMapping，RequestMappingHandlerMapping为springmvc的核心类，主要作用是转发请求到某个具体的方法。

MvcEndpoints神奇的地方在于其初始化代码：

    public void afterPropertiesSet() throws Exception {
        Collection<MvcEndpoint> existing = BeanFactoryUtils
                .beansOfTypeIncludingAncestors(this.applicationContext, MvcEndpoint.class)
                .values();
        this.endpoints.addAll(existing);
        this.customTypes = findEndpointClasses(existing);
        @SuppressWarnings("rawtypes")
        Collection<Endpoint> delegates = BeanFactoryUtils
                .beansOfTypeIncludingAncestors(this.applicationContext, Endpoint.class)
                .values();
        for (Endpoint<?> endpoint : delegates) {
            if (isGenericEndpoint(endpoint.getClass()) && endpoint.isEnabled()) {
                EndpointMvcAdapter adapter = new EndpointMvcAdapter(endpoint);
                String path = determinePath(endpoint,
                        this.applicationContext.getEnvironment());
                if (path != null) {
                    adapter.setPath(path);
                }
                this.endpoints.add(adapter);
            }
        }
    }

主要做了两件事：
1.查找spring的beanfactory中所有的MvcEndpoint类
2.查找spring的beanfactory中所有的Endpoint类
3.如果某个MvcEndpoint的getEndpointType方法的返回结果和某个Endpoint的class相冲突，则选取MvcEndpoint
4.查找选取的结果放在MvcEndpoints的endpoints方法中。

请注意MvcEndpoints和MvcEndpoint和Endpoint区别。

Endpoint是actuator的基本元素，一个Endpoint代表一个接口
Endpoint可以单独使用，单独使用时MvcEndpoints会使用EndpointMvcAdapter自动将Endpoint封装为MvcEndpoint对象
可以自己主动将Endpoint封装为MvcEndpoint
MvcEndpoint可以单独使用
MvcEndpoints的作用是将Endpoint和MvcEndpoint整合提供给EndpointHandlerMapping使用

自定义Endpoint

    @Bean
    public Endpoint<String> testEndPoint(){
        return new Endpoint<String>() {
            @Override
            public String getId() {
                return "test";
            }

            @Override
            public boolean isEnabled() {
                return true;
            }

            @Override
            public boolean isSensitive() {
                return false;
            }

            @Override
            public String invoke() {
                return "invokeingTestEndPoint";
            }
        };
    }

getId方法是path，这个path为：/actuator/test

自定义MvcEndpoint

    @Bean
    public MvcEndpoint testMvcEndpoint(){
        return new MvcEndpoint() {
            @Override
            public String getPath() {
                return "/testMvcEndpoint";
            }

            @Override
            public boolean isSensitive() {
                return false;
            }

            @RequestMapping("testMvcEndpoint")
            @ResponseBody
            public String get(){
                return "invokingTestMvcEndpoint";
            }

            @RequestMapping("testMvcEndpoint2")
            @ResponseBody
            public String ge2t(){
                return "invokingTestMvcEndpoint2";
            }

            @Override
            public Class<? extends Endpoint> getEndpointType() {
                return null;
            }
        };
    }

getPath()方法为path前缀，类似于controller类上的RequestMapping，实际的path需要拼接上各个方法定义的RequestMapping。
这个bean定义了两个path: