查漏补缺：连接器在Tomcat中是如何设计的

从连接器(Connector)源码说起

既然是来解析连接器(Connector)，那么我们直接从源码入手，后面所有源码我会剔除不重要部分，所以会忽略大部分源码细节，只关注流程。源码如下(高能预警，大量代码)：

public?class?Connector?extends?LifecycleMBeanBase?{?
?public?Connector()?{?
?this("org.apache.coyote.http11.Http11NioProtocol");?
?}?
?public?Connector(String?protocol)?{?
?boolean?aprConnector?=?AprLifecycleListener.isAprAvailable()?&&?
?AprLifecycleListener.getUseAprConnector();?
?if?("HTTP/1.1".equals(protocol)?||?protocol?==?null)?{?
?if?(aprConnector)?{?
?protocolHandlerClassName?=?"org.apache.coyote.http11.Http11AprProtocol";?
?}?else?{?
?protocolHandlerClassName?=?"org.apache.coyote.http11.Http11NioProtocol";?
?}?
?}?else?if?("AJP/1.3".equals(protocol))?{?
?if?(aprConnector)?{?
?protocolHandlerClassName?=?"org.apache.coyote.ajp.AjpAprProtocol";?
?}?else?{?
?protocolHandlerClassName?=?"org.apache.coyote.ajp.AjpNioProtocol";?
?}?
?}?else?{?
?protocolHandlerClassName?=?protocol;?
?}?
?//?Instantiate?protocol?handler?
?ProtocolHandler?p?=?null;?
?try?{?
?Class?clazz?=?Class.forName(protocolHandlerClassName);?
?p?=?(ProtocolHandler)?clazz.getConstructor().newInstance();?
?}?catch?(Exception?e)?{?
?log.error(sm.getString(?
?"coyoteConnector.protocolHandlerInstantiationFailed"),?e);?
?}?finally?{?
?this.protocolHandler?=?p;?
?}?
?//?Default?for?Connector?depends?on?this?system?property?
?setThrowOnFailure(Boolean.getBoolean("org.apache.catalina.startup.EXIT_ON_INIT_FAILURE"));?
?}?

我们来看看Connector的构造方法，其实只做了一件事情，就是根据协议设置对应的ProtocolHandler,根据名称我们知道，这是协议处理类，所以连接器内部的一个重要子模块就是ProtocolHandler。

关于生命周期

我们看到Connector继承了LifecycleMBeanBase，我们来看看Connector的最终继承关系：

我们看到最终实现的是Lifecycle接口,我们看看这个接口是何方神圣。我把其接口的注释拿下来解释下

/**?
?*?Common?interface?for?component?life?cycle?methods.?Catalina?components?
?*?may?implement?this?interface?(as?well?as?the?appropriate?interface(s)?for?
?*?the?functionality?they?support)?in?order?to?provide?a?consistent?mechanism?
?*?to?start?and?stop?the?component.?
?*?start()?
?*?-----------------------------?
?*?|?|?
?*?|?init()?|?
?*?NEW?-?--?INITIALIZING?|?
?*?|?|?|?|?------------------?-----------------------?
?*?|?|?|auto?|?|?|?
?*?|?|?\|/?start()?\|/?\|/?auto?auto?stop()?|?
?*?|?|?INITIALIZED?--?--?STARTING_PREP?--?-?STARTING?--?-?STARTED?--?---?|?
?*?|?|?|?|?|?
?*?|?|destroy()|?|?|?
?*?|?--?-----?--?------------------------?--------------------------------?^?
?*?|?|?|?|?
?*?|?|?\|/?auto?auto?start()?|?
?*?|?|?STOPPING_PREP?----?----?STOPPING?------?-----?STOPPED?-----?-----?
?*?|?\|/?^?|?^?
?*?|?|?stop()?|?|?|?
?*?|?|?--------------------------?|?|?
?*?|?|?|?|?|?
?*?|?|?|?destroy()?destroy()?|?|?
?*?|?|?FAILED?----?------?DESTROYING?---?-----------------?|?
?*?|?|?^?|?|?
?*?|?|?destroy()?|?|auto?|?
?*?|?--------?-----------------?\|/?|?
?*?|?DESTROYED?|?
?*?|?|?
?*?|?stop()?|?
?*?----?-----------------------------?------------------------------?
?*?
?*?Any?state?can?transition?to?FAILED.?
?*?
?*?Calling?start()?while?a?component?is?in?states?STARTING_PREP,?STARTING?or?
?*?STARTED?has?no?effect.?
?*?
?*?Calling?start()?while?a?component?is?in?state?NEW?will?cause?init()?to?be?
?*?called?immediately?after?the?start()?method?is?entered.?
?*?
?*?Calling?stop()?while?a?component?is?in?states?STOPPING_PREP,?STOPPING?or?
?*?STOPPED?has?no?effect.?
?*?
?*?Calling?stop()?while?a?component?is?in?state?NEW?transitions?the?component?
?*?to?STOPPED.?This?is?typically?encountered?when?a?component?fails?to?start?and?
?*?does?not?start?all?its?sub-components.?When?the?component?is?stopped,?it?will?
?*?try?to?stop?all?sub-components?-?even?those?it?didn't?start.?
?*?
?*?Attempting?any?other?transition?will?throw?{@link?LifecycleException}.?
?*?
?*?

【免责声明】本站内容转载自互联网，其相关言论仅代表作者个人观点绝非权威，不代表本站立场。如您发现内容存在版权问题，请提交相关链接至邮箱：bqsm@foxmail.com，我们将及时予以处理。