tomcat bootstrap启动步骤
TOMCAT以一个责任链贯穿Server的启动过程。首先是读取配置文件、由Server启动一个service，由service把connector和container组装起来对外界提供服务。
在tomcat6中connector包括三种不同的connector：1、Http Connector 基于HTTP协议，负责建立HTTP连接。它又分为BIO Http Connector与NIO Http Connector两种，后者提供非阻塞IO与长连接Comet支持。2、AJP Connector, 基于AJP协议，AJP是专门设计用来为tomcat与http服务器之间通信专门定制的协议，能提供较高的通信速度和效率。如与Apache服务器集成时，采用这个协议。3、APR HTTP Connector, 用C实现，通过JNI调用的。主要提升对静态资源（如HTML、图片、CSS、JS等）的访问性能。现在这个库已独立出来可用在任何项目中。Tomcat在配置APR之后性能非常强劲
Container 是容器的父接口，所有子容器都必须实现这个接口，Container 容器的设计最能体现责任链的设计模式；它有四个子容器组件构成，分别是：Engine、Host、Context、Wrapper。这四个组件不是平行的，而是父子关系， Engine 包含 Host,Host 包含 Context，Context 包含 Wrapper，通常一个 Servlet class 对应一个 Wrapper，如果有多个 Servlet 就可以定义多个 Wrapper
if (daemon == null) { daemon = new Bootstrap(); try { daemon.init(); } catch (Throwable t) { t.printStackTrace(); return; } }daemon.setAwait(true); daemon.load(args); daemon.start();
// Start the new server if (getServer() instanceof Lifecycle) { try { ((Lifecycle) getServer()).start(); } catch (LifecycleException e) { log.error("Catalina.start: ", e); } }// Validate and update our current component state if (started) { log.debug(sm.getString("standardServer.start.started")); return; } // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null); lifecycle.fireLifecycleEvent(START_EVENT, null); started = true; // Start our defined Services synchronized (services) { for (int i = 0; i < services.length; i++) { if (services[i] instanceof Lifecycle) ((Lifecycle) services[i]).start(); } } // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);// Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null); if(log.isInfoEnabled()) log.info(sm.getString("standardService.start.name", this.name)); lifecycle.fireLifecycleEvent(START_EVENT, null); started = true; // Start our defined Container first if (container != null) { synchronized (container) { if (container instanceof Lifecycle) { ((Lifecycle) container).start(); } } } synchronized (executors) { for ( int i=0; i<executors.size(); i++ ) { executors.get(i).start(); } } // Start our defined Connectors second synchronized (connectors) { for (int i = 0; i < connectors.length; i++) { try { ((Lifecycle) connectors[i]).start(); } catch (Exception e) { log.error(sm.getString( "standardService.connector.startFailed", connectors[i]), e); } } } // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);// Standard container startup super.start();
// Validate and update our current component state if (started) { if(log.isInfoEnabled()) log.info(sm.getString("containerBase.alreadyStarted", logName())); return; } // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null); started = true; // Start our subordinate components, if any if ((loader != null) && (loader instanceof Lifecycle)) ((Lifecycle) loader).start(); logger = null; getLogger(); if ((logger != null) && (logger instanceof Lifecycle)) ((Lifecycle) logger).start(); if ((manager != null) && (manager instanceof Lifecycle)) ((Lifecycle) manager).start(); if ((cluster != null) && (cluster instanceof Lifecycle)) ((Lifecycle) cluster).start(); if ((realm != null) && (realm instanceof Lifecycle)) ((Lifecycle) realm).start(); if ((resources != null) && (resources instanceof Lifecycle)) ((Lifecycle) resources).start(); // Start our child containers, if any Container children[] = findChildren(); for (int i = 0; i < children.length; i++) { if (children[i] instanceof Lifecycle) ((Lifecycle) children[i]).start(); } // Start the Valves in our pipeline (including the basic), if any if (pipeline instanceof Lifecycle) ((Lifecycle) pipeline).start(); // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(START_EVENT, null); // Start our thread threadStart(); // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);