StatusManager接口针对status定义了add、getCopyOfStatusList、getCount、clear方法，针对StatusListener定义了add、remove、getCopyOfStatusListenerList方法

StatusListener定义了addStatusEvent方法，注册到logback上下文的StatusManager的StatusListener将接收每个传入状态消息

OptionHelper提供了substVars方法，它执行NodeToStringTransformer的substituteVariable方法

org/springframework/boot/logging/logback/SpringBootJoranConfigurator.java

LoggingSystem定义了beforeInitialize抽象方法，需要子类实现，，同时还提供了setLogLevel、getLoggerConfigurations、getLoggerConfiguration，默认是抛出UnsupportedOperationException

springboot的actuator定义了LoggersEndpoint，它构造器依赖loggingSystem及loggerGroups

spring-boot包含了defaults.xml，它定义了一些conversionRule、CONSOLE_LOG_PATTERN、FILE_LOG_PATTERN变量以及一些logger

start方法要求fileName必须有值，在prudent模式下会强制开启append；另外start的时候会执行checkForFileCollisionInPreviousFileAppenders判断是否有冲突，没有冲突则执行openFile方法

logback-core/src/main/java/ch/qos/logback/core/OutputStreamAppender.java

AsyncAppender继承了AsyncAppenderBase，它新增了includeCallerData配置，另外覆盖了isDiscardable、preprocess方法，isDiscardable针对TRACE、DEBUG的级别返回true，INFO返回false；preprocess则判断是否includeCallerData，是的话则执行eventObject.getCallerData()

org/springframework/boot/actuate/autoconfigure/metrics/web/tomcat/TomcatMetricsAutoConfiguration.java

序本文主要研究一下HttpClient的closeCloseableHttpClientorg/apache/http/impl/client/CloseableHttpClient.java {代码...} CloseableHttpClient声明实现HttpClient, Closeable接口InternalHttpClientorg/apache/http/impl/client/InternalHttpClient.java {代码...} InternalHttpClient继承了CloseableHttpClient，其...

这里取了maxIdle配置来进行预热，通过DirectFieldAccessor来获取jedisConnectionFactory对象的pool

org/springframework/boot/autoconfigure/availability/ApplicationAvailabilityAutoConfiguration.java

序本文主要研究一下线程池的预热prestartCoreThreadjava/util/concurrent/ThreadPoolExecutor.java {代码...} ThreadPoolExecutor定义了prestartCoreThread，用于启动一个核心线程prestartAllCoreThreadsjava/util/concurrent/ThreadPoolExecutor.java {代码...} prestartAllCoreThreads用于启动所有的核心线程小结Threa...

org/springframework/kafka/annotation/KafkaListenerAnnotationBeanPostProcessor.java

实现了RocketMQListener接口的类，再配合@RocketMQMessageListener注解就可以实现对rocketmq消息的消费

spring-beans/src/main/java/org/springframework/beans/factory/DisposableBean.java

spring-beans/src/main/java/org/springframework/beans/factory/annotation/InitDestroyAnnotationBeanPostProcessor.java

RedirectStrategy接口定义了isRedirected方法用于判断是否需要redirect，还定义了getRedirect方法用于返回redirect的目标地址

序本文主要研究一下HttpClient的DnsResolverDnsResolverorg/apache/http/conn/DnsResolver.java {代码...} DnsResolver定义了resolve方法，可用于替换OS提供的DNS lookupInMemoryDnsResolverorg/apache/http/impl/conn/InMemoryDnsResolver.java {代码...} InMemoryDnsResolver实现了DnsResolver接口，它用一个Concurren...

序本文主要研究一下HttpClient的HttpRoutePlannerHttpRoutePlannerorg/apache/http/conn/routing/HttpRoutePlanner.java {代码...} HttpRoutePlanner接口定义了determineRoute方法，用于决定该请求的目标routeDefaultRoutePlannerorg/apache/http/impl/conn/DefaultRoutePlanner.java {代码...} DefaultRoutePlanner实现...

BackoffManager接口主要用于根据connection的情况来动态调整连接池的connection大小，它定义了backOff方法用于缩小连接数，probe方法用于扩大连接数

序本文主要研究一下HttpClient的ConnectionBackoffStrategyConnectionBackoffStrategyorg/apache/http/client/ConnectionBackoffStrategy.java {代码...} ConnectionBackoffStrategy定义了shouldBackoff方法，它根据异常或者response来进行判断NullBackoffStrategyorg/apache/http/impl/client/NullBackoffStrategy.java...

ServiceUnavailableRetryStrategy定义了retryRequest方法用于返回是否该重试，getRetryInterval返回自动重试的间隔

HttpRequestRetryHandler接口定义了retryRequest方法，它接收IOException、executionCount及context，然后判断是否可以重试

序本文主要研究一下HttpClient的NoHttpResponseExceptionNoHttpResponseExceptionorg/apache/http/NoHttpResponseException.java {代码...} NoHttpResponseException继承了IOException，用于表示目标服务器没有返回一个正常的http responseDefaultHttpResponseParserorg/apache/http/impl/conn/DefaultHttpResponseParse...

ConnectionKeepAliveStrategy接口定义了getKeepAliveDuration方法，用于返回该connection空间多久以内被复用是安全的

序本文主要研究一下HttpClient的ResponseHandlerResponseHandlerorg/apache/http/client/ResponseHandler.java {代码...} ResponseHandler定义了handleResponse方法，用于解析HttpResponse到泛型TAbstractResponseHandlerorg/apache/http/impl/client/AbstractResponseHandler.java {代码...} AbstractResponseHandler声...

org/springframework/http/client/HttpComponentsClientHttpRequestFactory.java