# 1. 简介
>Spring Boot的Endpoint主要是用来监控应用服务的运行状况，并集成在MVC中提供查看接口。内置的Endpoint比如HealthEndpoint会监控dist和db的状况
# 2. 分析
## 2.1 Endpoint源码
Endpoint是在包**org.springframework.boot.actuate.endpoint**下，其中**invoke()**是最主要的方法，用于返回监控的内容，isSensitive()用于权限控制。核心代码如下：
```
public interface Endpoint {
String getId();
boolean isEnabled();
boolean isSensitive();
T invoke();
}
```
## 2.2 Endpoint加载实现
Endpoint的加载还是要依靠**spring.factories**实现的。Spring-boot-actutor包下的**META-IN/spring.factories**配置了**EndpointAutoConfiguration**。
**spring.factories代码如下**
```
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.actuate.autoconfigure.AuditAutoConfiguration,\
org.springframework.boot.actuate.autoconfigure.CacheStatisticsAutoConfiguration,\
org.springframework.boot.actuate.autoconfigure.CrshAutoConfiguration,\
```
## 2.3 EndpointAutoConfiguration自动加载类
**EndpointAutoConfiguration（org.springframework.boot.actuate.autoconfigure包下）**就会注入必要的**Endpoint**。有些Endpoint需要外部的收集类，比如TraceEndpoint。
```
* Copyright 2012-2016 the original author or authors.
package org.springframework.boot.actuate.autoconfigure;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import liquibase.integration.spring.SpringLiquibase;
import org.flywaydb.core.Flyway;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.actuate.endpoint.AutoConfigurationReportEndpoint;
import org.springframework.boot.actuate.endpoint.BeansEndpoint;
import org.springframework.boot.actuate.endpoint.ConfigurationPropertiesReportEndpoint;
import org.springframework.boot.actuate.endpoint.DumpEndpoint;
import org.springframework.boot.actuate.endpoint.Endpoint;
import org.springframework.boot.actuate.endpoint.EndpointProperties;
import org.springframework.boot.actuate.endpoint.EnvironmentEndpoint;
import org.springframework.boot.actuate.endpoint.FlywayEndpoint;
import org.springframework.boot.actuate.endpoint.HealthEndpoint;
import org.springframework.boot.actuate.endpoint.InfoEndpoint;
import org.springframework.boot.actuate.endpoint.LiquibaseEndpoint;
import org.springframework.boot.actuate.endpoint.LoggersEndpoint;
import org.springframework.boot.actuate.endpoint.MetricsEndpoint;
import org.springframework.boot.actuate.endpoint.PublicMetrics;
import org.springframework.boot.actuate.endpoint.RequestMappingEndpoint;
import org.springframework.boot.actuate.endpoint.ShutdownEndpoint;
import org.springframework.boot.actuate.endpoint.TraceEndpoint;
import org.springframework.boot.actuate.health.HealthAggregator;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.boot.actuate.health.OrderedHealthAggregator;
import org.springframework.boot.actuate.info.InfoContributor;
import org.springframework.boot.actuate.trace.InMemoryTraceRepository;
import org.springframework.boot.actuate.trace.TraceRepository;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionEvaluationReport;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.SearchStrategy;
import org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration;
import org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.logging.LoggingSystem;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.web.servlet.handler.AbstractHandlerMethodMapping;
/**
* {@link EnableAutoConfiguration Auto-configuration} for common management
* {@link Endpoint}s.
*
* @author Dave Syer
* @author Phillip Webb
* @author Greg Turnquist
* @author Christian Dupuis
* @author Stephane Nicoll
* @author Eddú Meléndez
* @author Meang Akira Tanaka
* @author Ben Hale
*/
@Configuration
@AutoConfigureAfter({ FlywayAutoConfiguration.class, LiquibaseAutoConfiguration.class })
@EnableConfigurationProperties(EndpointProperties.class)
public class EndpointAutoConfiguration {
private final HealthAggregator healthAggregator;
private final Map healthIndicators;
private final List infoContributors;
private final Collection publicMetrics;
private final TraceRepository traceRepository;
public EndpointAutoConfiguration(ObjectProvider healthAggregator,
ObjectProvider> healthIndicators,
ObjectProvider> infoContributors,
ObjectProvider> publicMetrics,
ObjectProvider traceRepository) {
this.healthAggregator = healthAggregator.getIfAvailable();
this.healthIndicators = healthIndicators.getIfAvailable();
this.infoContributors = infoContributors.getIfAvailable();
this.publicMetrics = publicMetrics.getIfAvailable();
this.traceRepository = traceRepository.getIfAvailable();
}
@Bean
@ConditionalOnMissingBean
public EnvironmentEndpoint environmentEndpoint() {
return new EnvironmentEndpoint();
}
@Bean
@ConditionalOnMissingBean
public HealthEndpoint healthEndpoint() {
return new HealthEndpoint(
this.healthAggregator == null ? new OrderedHealthAggregator()
: this.healthAggregator,
this.healthIndicators == null
? Collections.emptyMap()
: this.healthIndicators);
}
@Bean
@ConditionalOnMissingBean
public BeansEndpoint beansEndpoint() {
return new BeansEndpoint();
}
@Bean
@ConditionalOnMissingBean
public InfoEndpoint infoEndpoint() throws Exception {
return new InfoEndpoint(this.infoContributors == null
? Collections.emptyList() : this.infoContributors);
}
@Bean
@ConditionalOnBean(LoggingSystem.class)
@ConditionalOnMissingBean
public LoggersEndpoint loggersEndpoint(LoggingSystem loggingSystem) {
return new LoggersEndpoint(loggingSystem);
}
@Bean
@ConditionalOnMissingBean
public MetricsEndpoint metricsEndpoint() {
List publicMetrics = new ArrayList();
if (this.publicMetrics != null) {
publicMetrics.addAll(this.publicMetrics);
}
Collections.sort(publicMetrics, AnnotationAwareOrderComparator.INSTANCE);
return new MetricsEndpoint(publicMetrics);
}
@Bean
@ConditionalOnMissingBean
public TraceEndpoint traceEndpoint() {
return new TraceEndpoint(this.traceRepository == null
? new InMemoryTraceRepository() : this.traceRepository);
}
@Bean
@ConditionalOnMissingBean
public DumpEndpoint dumpEndpoint() {
return new DumpEndpoint();
}
@Bean
@ConditionalOnBean(ConditionEvaluationReport.class)
@ConditionalOnMissingBean(search = SearchStrategy.CURRENT)
public AutoConfigurationReportEndpoint autoConfigurationReportEndpoint() {
return new AutoConfigurationReportEndpoint();
}
@Bean
@ConditionalOnMissingBean
public ShutdownEndpoint shutdownEndpoint() {
return new ShutdownEndpoint();
}
@Bean
@ConditionalOnMissingBean
public ConfigurationPropertiesReportEndpoint configurationPropertiesReportEndpoint() {
return new ConfigurationPropertiesReportEndpoint();
}
@Configuration
@ConditionalOnBean(Flyway.class)
@ConditionalOnClass(Flyway.class)
static class FlywayEndpointConfiguration {
@Bean
@ConditionalOnMissingBean
public FlywayEndpoint flywayEndpoint(Map flyways) {
return new FlywayEndpoint(flyways);
}
}
@Configuration
@ConditionalOnBean(SpringLiquibase.class)
@ConditionalOnClass(SpringLiquibase.class)
static class LiquibaseEndpointConfiguration {
@Bean
@ConditionalOnMissingBean
public LiquibaseEndpoint liquibaseEndpoint(
Map liquibases) {
return new LiquibaseEndpoint(liquibases);
}
}
@Configuration
@ConditionalOnClass(AbstractHandlerMethodMapping.class)
protected static class RequestMappingEndpointConfiguration {
@Bean
@ConditionalOnMissingBean
public RequestMappingEndpoint requestMappingEndpoint() {
RequestMappingEndpoint endpoint = new RequestMappingEndpoint();
return endpoint;
}
}
}
```
**TraceEndpoint**会记录每次请求的**Request和Response**的状态，需要嵌入到Request的流程中，这里就主要用到了3个类。
## 2.4 **TraceRepository**用于保存和获取**Request和Response**的状态。
```
* Copyright 2012-2015 the original author or authors.
package org.springframework.boot.actuate.trace;
import java.util.List;
import java.util.Map;
/**
* A repository for {@link Trace}s.
*
* @author Dave Syer
*/
public interface TraceRepository {
/**
* Find all {@link Trace} objects contained in the repository.
* @return the results
*/
List findAll();
/**
* Add a new {@link Trace} object at the current time.
* @param traceInfo trace information
*/
void add(Map traceInfo);
}
```
## 2.5 WebRequestTraceFilter用于嵌入web request，收集请求的状态并保存在TraceRepository中。
## 2.6 TraceEndpoint，invoke()方法直接调用TraceRepository保存的数据。
```
* Copyright 2012-2016 the original author or authors.
package org.springframework.boot.actuate.endpoint;
import java.util.List;
import org.springframework.boot.actuate.trace.Trace;
import org.springframework.boot.actuate.trace.TraceRepository;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.util.Assert;
/**
* {@link Endpoint} to expose {@link Trace} information.
*
* @author Dave Syer
*/
@ConfigurationProperties(prefix = "endpoints.trace")
public class TraceEndpoint extends AbstractEndpoint> {
private final TraceRepository repository;
/**
* Create a new {@link TraceEndpoint} instance.
* @param repository the trace repository
*/
public TraceEndpoint(TraceRepository repository) {
super("trace");
Assert.notNull(repository, "Repository must not be null");
this.repository = repository;
}
@Override
public List invoke() {
return this.repository.findAll();
}
}
```
# 3. 总结
很多spring-starter都是基于是spring.factories的配置实现，可以完美的提高复用性，模块化开发。可以利用好endpoint实现不少的监控统计功能
Spring-Endpoint基本原理
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