tomcat--catalina

Servlet容器是tomcat的核心组件，所有基于jsp/servlet的Java web应用均需要依托servlet容器运行并对外提供服务。

tomcat本质上是一款servlet容器，因此Catalina是tomcat的核心，其它模块均为catalina提供支持。

Digester
Catalina使用digester解析xml配置文件，并创建应用服务器。

digester主要有对象栈、匹配模式和处理规则三部分。

对象栈保存各个节点对象。

digest用法：

解析用的代码：

 public static void ts1() throws IOException, SAXException {Digester digester=new Digester();digester.setValidating(false);digester.setRulesValidation(true);digester.addObjectCreate("department",Department.class.getName());digester.addSetProperties("department");//匹配到department节点时，设置对象属性.比如name,age等自定义属性自动装填。digester.addObjectCreate("department/user",User.class.getName());digester.addSetProperties("department/user");digester.addSetNext("department/user","addUser",User.class.getName());digester.addCallMethod("department/extension","putExtension",2);digester.addCallParam("department/extension/property-name",0);digester.addCallParam("department/extension/property-value",1);Department d= (Department) digester.parse(TestMain.class.getResourceAsStream("/test.xml"));System.out.println(d.getCode());}

原文：

<?xml version="1.0" encoding="UTF-8" ?>
<department><user name="un1" code="uc1"></user><user name="un2" code="uc2"></user><extension><property-name>director</property-name><property-value>joke</property-value></extension>
</department>

Department和user是自定义的类，用于描述文件属性。

catalina类通过下面这个方法，创建了digester类。

protected Digester createStartDigester() {long t1 = System.currentTimeMillis();Digester digester = new Digester();digester.setValidating(false);digester.setRulesValidation(true);Map<Class<?>, List<String>> fakeAttributes = new HashMap();List<String> attrs = new ArrayList();attrs.add("className");fakeAttributes.put(Object.class, attrs);digester.setFakeAttributes(fakeAttributes);digester.setUseContextClassLoader(true);digester.addObjectCreate("Server", "org.apache.catalina.core.StandardServer", "className");//创建server对象，如果有自定义className,则使用自定义的属性digester.addSetProperties("Server");//装填属性digester.addSetNext("Server", "setServer", "org.apache.catalina.Server");//设置到catalina类中digester.addObjectCreate("Server/GlobalNamingResources", "org.apache.catalina.deploy.NamingResourcesImpl");//创建Java EE企业命名上下文digester.addSetProperties("Server/GlobalNamingResources");digester.addSetNext("Server/GlobalNamingResources", "setGlobalNamingResources", "org.apache.catalina.deploy.NamingResourcesImpl");//将其设置到server实例中//为server创建声明周期监听器digester.addObjectCreate("Server/Listener", (String)null, "className");digester.addSetProperties("Server/Listener");digester.addSetNext("Server/Listener", "addLifecycleListener", "org.apache.catalina.LifecycleListener");//className指定LifecycleListener，Catalina默认配置了5个监听器。//Apr 在server初始化前加载APR库，并在server停止后销毁                 //VersionLogger  server初始化前打印操作系统，jvm以及服务器版本信息//JreMemoryLeakPreventionListener   server初始化前调用，以解决单例对象创建导致的jvm内存泄漏以及锁文件问题//GlobalResourcesLifecycleListener server启动时，将JNDI资源注册为MBean管理//ThreadLocalLeakPrevention 用于在context停止时重建Executor池中 的线程，避免导致内存泄漏//构建service实例digester.addObjectCreate("Server/Service", "org.apache.catalina.core.StandardService", "className");digester.addSetProperties("Server/Service");digester.addSetNext("Server/Service", "addService", "org.apache.catalina.Service");//把实例添加到server中//为service添加生命周期监听器，默认情况下，Catalina未指定service监听器digester.addObjectCreate("Server/Service/Listener", (String)null, "className");digester.addSetProperties("Server/Service/Listener");digester.addSetNext("Server/Service/Listener", "addLifecycleListener", "org.apache.catalina.LifecycleListener");//为service添加Executordigester.addObjectCreate("Server/Service/Executor", "org.apache.catalina.core.StandardThreadExecutor", "className");digester.addSetProperties("Server/Service/Executor");digester.addSetNext("Server/Service/Executor", "addExecutor", "org.apache.catalina.Executor");//为service添加connector，排除executor和sslImplementationNamedigester.addRule("Server/Service/Connector", new ConnectorCreateRule());digester.addRule("Server/Service/Connector", new SetAllPropertiesRule(new String[]{"executor", "sslImplementationName", "protocol"}));digester.addSetNext("Server/Service/Connector", "addConnector", "org.apache.catalina.connector.Connector");//为connector添加虚拟主机SSL配置digester.addObjectCreate("Server/Service/Connector/SSLHostConfig", "org.apache.tomcat.util.net.SSLHostConfig");digester.addSetProperties("Server/Service/Connector/SSLHostConfig");digester.addSetNext("Server/Service/Connector/SSLHostConfig", "addSslHostConfig", "org.apache.tomcat.util.net.SSLHostConfig");digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate", new CertificateCreateRule());digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate", new SetAllPropertiesRule(new String[]{"type"}));digester.addSetNext("Server/Service/Connector/SSLHostConfig/Certificate", "addCertificate", "org.apache.tomcat.util.net.SSLHostConfigCertificate");digester.addObjectCreate("Server/Service/Connector/SSLHostConfig/OpenSSLConf", "org.apache.tomcat.util.net.openssl.OpenSSLConf");digester.addSetProperties("Server/Service/Connector/SSLHostConfig/OpenSSLConf");digester.addSetNext("Server/Service/Connector/SSLHostConfig/OpenSSLConf", "setOpenSslConf", "org.apache.tomcat.util.net.openssl.OpenSSLConf");digester.addObjectCreate("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd", "org.apache.tomcat.util.net.openssl.OpenSSLConfCmd");digester.addSetProperties("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd");digester.addSetNext("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd", "addCmd", "org.apache.tomcat.util.net.openssl.OpenSSLConfCmd");//为connector添加生命周期监听器digester.addObjectCreate("Server/Service/Connector/Listener", (String)null, "className");digester.addSetProperties("Server/Service/Connector/Listener");digester.addSetNext("Server/Service/Connector/Listener", "addLifecycleListener", "org.apache.catalina.LifecycleListener");//为connector添加升级协议，用于支持HTTP/2digester.addObjectCreate("Server/Service/Connector/UpgradeProtocol", (String)null, "className");digester.addSetProperties("Server/Service/Connector/UpgradeProtocol");digester.addSetNext("Server/Service/Connector/UpgradeProtocol", "addUpgradeProtocol", "org.apache.coyote.UpgradeProtocol");//添加子元素解析规则digester.addRuleSet(new NamingRuleSet("Server/GlobalNamingResources/"));digester.addRuleSet(new EngineRuleSet("Server/Service/"));digester.addRuleSet(new HostRuleSet("Server/Service/Engine/"));digester.addRuleSet(new ContextRuleSet("Server/Service/Engine/Host/"));this.addClusterRuleSet(digester, "Server/Service/Engine/Host/Cluster/");digester.addRuleSet(new NamingRuleSet("Server/Service/Engine/Host/Context/"));digester.addRule("Server/Service/Engine", new SetParentClassLoaderRule(this.parentClassLoader));this.addClusterRuleSet(digester, "Server/Service/Engine/Cluster/");long t2 = System.currentTimeMillis();if(log.isDebugEnabled()) {log.debug("Digester for server.xml created " + (t2 - t1));}return digester;}

Engine的解析

默认实现是StandardEngine，提供了默认配置EngineConfig用于打印engine的启动和停止日志。

 public void addRuleInstances(Digester digester) {digester.addObjectCreate(this.prefix + "Engine", "org.apache.catalina.core.StandardEngine", "className");digester.addSetProperties(this.prefix + "Engine");digester.addRule(this.prefix + "Engine", new LifecycleListenerRule("org.apache.catalina.startup.EngineConfig", "engineConfigClass"));digester.addSetNext(this.prefix + "Engine", "setContainer", "org.apache.catalina.Engine");//添加到service实例中//添加集群配置digester.addObjectCreate(this.prefix + "Engine/Cluster", (String)null, "className");digester.addSetProperties(this.prefix + "Engine/Cluster");digester.addSetNext(this.prefix + "Engine/Cluster", "setCluster", "org.apache.catalina.Cluster");//添加生命周期监听器digester.addObjectCreate(this.prefix + "Engine/Listener", (String)null, "className");digester.addSetProperties(this.prefix + "Engine/Listener");digester.addSetNext(this.prefix + "Engine/Listener", "addLifecycleListener", "org.apache.catalina.LifecycleListener");//添加安全配置digester.addRuleSet(new RealmRuleSet(this.prefix + "Engine/"));digester.addObjectCreate(this.prefix + "Engine/Valve", (String)null, "className");digester.addSetProperties(this.prefix + "Engine/Valve");digester.addSetNext(this.prefix + "Engine/Valve", "addValve", "org.apache.catalina.Valve");}

host解析

public void addRuleInstances(Digester digester) {digester.addObjectCreate(this.prefix + "Host", "org.apache.catalina.core.StandardHost", "className");digester.addSetProperties(this.prefix + "Host");//注入属性digester.addRule(this.prefix + "Host", new CopyParentClassLoaderRule());digester.addRule(this.prefix + "Host", new LifecycleListenerRule("org.apache.catalina.startup.HostConfig", "hostConfigClass"));//添加监听器digester.addSetNext(this.prefix + "Host", "addChild", "org.apache.catalina.Container");//把它添加到engine中digester.addCallMethod(this.prefix + "Host/Alias", "addAlias", 0);//添加别名//添加集群，为Hostdigester.addObjectCreate(this.prefix + "Host/Cluster", (String)null, "className");digester.addSetProperties(this.prefix + "Host/Cluster");digester.addSetNext(this.prefix + "Host/Cluster", "setCluster", "org.apache.catalina.Cluster");//添加生命周期管理digester.addObjectCreate(this.prefix + "Host/Listener", (String)null, "className");digester.addSetProperties(this.prefix + "Host/Listener");digester.addSetNext(this.prefix + "Host/Listener", "addLifecycleListener", "org.apache.catalina.LifecycleListener");//添加安全管理digester.addRuleSet(new RealmRuleSet(this.prefix + "Host/"));digester.addObjectCreate(this.prefix + "Host/Valve", (String)null, "className");digester.addSetProperties(this.prefix + "Host/Valve");digester.addSetNext(this.prefix + "Host/Valve", "addValve", "org.apache.catalina.Valve");}

context解析

create为true时，表示通过server.xml配置context。
create为false时，通过HostConfig创建context。

public void addRuleInstances(Digester digester) {if(this.create) {digester.addObjectCreate(this.prefix + "Context", "org.apache.catalina.core.StandardContext", "className");digester.addSetProperties(this.prefix + "Context");} else {digester.addRule(this.prefix + "Context", new SetContextPropertiesRule());}if(this.create) {digester.addRule(this.prefix + "Context", new LifecycleListenerRule("org.apache.catalina.startup.ContextConfig", "configClass"));//生命周期监听器，用于详细配置context，如详细解析web.xmldigester.addSetNext(this.prefix + "Context", "addChild", "org.apache.catalina.Container");}digester.addObjectCreate(this.prefix + "Context/Listener", (String)null, "className");digester.addSetProperties(this.prefix + "Context/Listener");digester.addSetNext(this.prefix + "Context/Listener", "addLifecycleListener", "org.apache.catalina.LifecycleListener");
//指定生命周期监听器digester.addObjectCreate(this.prefix + "Context/Loader", "org.apache.catalina.loader.WebappLoader", "className");digester.addSetProperties(this.prefix + "Context/Loader");digester.addSetNext(this.prefix + "Context/Loader", "setLoader", "org.apache.catalina.Loader");
//指定类加载器digester.addObjectCreate(this.prefix + "Context/Manager", "org.apache.catalina.session.StandardManager", "className");digester.addSetProperties(this.prefix + "Context/Manager");digester.addSetNext(this.prefix + "Context/Manager", "setManager", "org.apache.catalina.Manager");digester.addObjectCreate(this.prefix + "Context/Manager/Store", (String)null, "className");digester.addSetProperties(this.prefix + "Context/Manager/Store");digester.addSetNext(this.prefix + "Context/Manager/Store", "setStore", "org.apache.catalina.Store");digester.addObjectCreate(this.prefix + "Context/Manager/SessionIdGenerator", "org.apache.catalina.util.StandardSessionIdGenerator", "className");digester.addSetProperties(this.prefix + "Context/Manager/SessionIdGenerator");digester.addSetNext(this.prefix + "Context/Manager/SessionIdGenerator", "setSessionIdGenerator", "org.apache.catalina.SessionIdGenerator");
//会话管理器digester.addObjectCreate(this.prefix + "Context/Parameter", "org.apache.tomcat.util.descriptor.web.ApplicationParameter");digester.addSetProperties(this.prefix + "Context/Parameter");digester.addSetNext(this.prefix + "Context/Parameter", "addApplicationParameter", "org.apache.tomcat.util.descriptor.web.ApplicationParameter");
//添加初始化参数，这个会导致应用与tomcat紧耦合（一般很少更换服务容器，所以这个其实没什么影响）。digester.addRuleSet(new RealmRuleSet(this.prefix + "Context/"));digester.addObjectCreate(this.prefix + "Context/Resources", "org.apache.catalina.webresources.StandardRoot", "className");digester.addSetProperties(this.prefix + "Context/Resources");digester.addSetNext(this.prefix + "Context/Resources", "setResources", "org.apache.catalina.WebResourceRoot");digester.addObjectCreate(this.prefix + "Context/Resources/PreResources", (String)null, "className");digester.addSetProperties(this.prefix + "Context/Resources/PreResources");digester.addSetNext(this.prefix + "Context/Resources/PreResources", "addPreResources", "org.apache.catalina.WebResourceSet");digester.addObjectCreate(this.prefix + "Context/Resources/JarResources", (String)null, "className");digester.addSetProperties(this.prefix + "Context/Resources/JarResources");digester.addSetNext(this.prefix + "Context/Resources/JarResources", "addJarResources", "org.apache.catalina.WebResourceSet");digester.addObjectCreate(this.prefix + "Context/Resources/PostResources", (String)null, "className");digester.addSetProperties(this.prefix + "Context/Resources/PostResources");digester.addSetNext(this.prefix + "Context/Resources/PostResources", "addPostResources", "org.apache.catalina.WebResourceSet");
//添加安全配置以及资源配置digester.addObjectCreate(this.prefix + "Context/ResourceLink", "org.apache.tomcat.util.descriptor.web.ContextResourceLink");digester.addSetProperties(this.prefix + "Context/ResourceLink");digester.addRule(this.prefix + "Context/ResourceLink", new SetNextNamingRule("addResourceLink", "org.apache.tomcat.util.descriptor.web.ContextResourceLink"));//添加资源链接，用于Java EE   命名服务digester.addObjectCreate(this.prefix + "Context/Valve", (String)null, "className");digester.addSetProperties(this.prefix + "Context/Valve");digester.addSetNext(this.prefix + "Context/Valve", "addValve", "org.apache.catalina.Valve");
//添加拦截器Valuedigester.addCallMethod(this.prefix + "Context/WatchedResource", "addWatchedResource", 0);//添加监视资源，这些资源发生变化时，web应用会重新加载，默认是web.xmldigester.addCallMethod(this.prefix + "Context/WrapperLifecycle", "addWrapperLifecycle", 0);//为context添加生命周期监听器，添加到context包含的wrapper上digester.addCallMethod(this.prefix + "Context/WrapperListener", "addWrapperListener", 0);digester.addObjectCreate(this.prefix + "Context/JarScanner", "org.apache.tomcat.util.scan.StandardJarScanner", "className");digester.addSetProperties(this.prefix + "Context/JarScanner");digester.addSetNext(this.prefix + "Context/JarScanner", "setJarScanner", "org.apache.tomcat.JarScanner");digester.addObjectCreate(this.prefix + "Context/JarScanner/JarScanFilter", "org.apache.tomcat.util.scan.StandardJarScanFilter", "className");digester.addSetProperties(this.prefix + "Context/JarScanner/JarScanFilter");digester.addSetNext(this.prefix + "Context/JarScanner/JarScanFilter", "setJarScanFilter", "org.apache.tomcat.JarScanFilter");
//添加守护资源配置digester.addObjectCreate(this.prefix + "Context/CookieProcessor", "org.apache.tomcat.util.http.Rfc6265CookieProcessor", "className");digester.addSetProperties(this.prefix + "Context/CookieProcessor");digester.addSetNext(this.prefix + "Context/CookieProcessor", "setCookieProcessor", "org.apache.tomcat.util.http.CookieProcessor");}//添加cookie管理器

web应用加载是server启动的核心处理过程，Catalina通过Standard host、hostconfig，standardcontext、contextConfig、standardWrapper这5个类完成对web应用的加载。

StandardHost加载web应用（即standardContext）的入口有2个，其中一个入口是由生命周期管理接口调用start方法启动，这是配置context元素在host元素内（解析server.xml时会创建context），这种方式不好用，因为每部署一个web应用，都需要在这来配置。

另一个入口是HostConfig自动扫描部署目录，创建context实例并启动。

StandardHost启动加载过程：

为host添加一个Value实现ErrorReportValue(也可以修改host的errorReportValueClass属性指定自己的错误处理Value),用于在服务器处理异常时输出错误页面。如果web.xml中没有添加错误处理页面，tomcat就会返回这个类生成的页面。
调用StandardHost父类ContainerBase的startInternal方法启动虚拟主机，处理分为以下几步
1. 如果配置了集群组件Cluster，则启动
2. 如果配置了安全组件Realm，则启动
3. 启动子节点
4. 启动Host持有的Pipeline组件
5. 设置Host状态为Starting,此时会触发StartEvent事件，HostConfig监听这个事件，扫描Web部署目录，对于部署描述文件、WAR包等，会自动创建StandardContext实例，并添加到Context中。
6. 启动Host层级的后台任务处理：Cluster后台任务、Realm后台任务处理、Pipeline中Value的后台任务处理。

HostConfig----它是一个LifecycleListener实现，由catalina添加到Host实例上。处理的生命周期事件包括Start_EVENT,PERIODIC_EVENT,STOP_EVENT。前两者与web应用部署密切相关，后者用于在Host停止时注销其对应的MBean。

START_EVENT事件
该事件在host启动时触发，完成服务器启动过程中的web应用部署（需要deployOnStartup为true，默认是true）。
· context描述文件部署：tomcat支持通过一个独立的Context描述文件来配置并启动web应用，配置方式如同server.xml中的context元素。配置文件的存储路径由host的xmlBase属性指定，默认为$CATALINA_BASE/conf/< Engine名称 >/host名称。
这个就会加载test/myApp目录下的应用，访问路径则path。

context的描述文件由hostConfig进行扫描和解析，而hostconfig会使用线程池同时解析多个context的xml文件。

而每个线程使用以下代码解析单个xml文件：

 protected void deployDescriptor(ContextName cn, File contextXml) {HostConfig.DeployedApplication deployedApp = new HostConfig.DeployedApplication(cn.getName(), true);long startTime = 0L;if(log.isInfoEnabled()) {startTime = System.currentTimeMillis();log.info(sm.getString("hostConfig.deployDescriptor", new Object[]{contextXml.getAbsolutePath()}));}Context context = null;boolean isExternalWar = false;boolean isExternal = false;File expandedDocBase = null;boolean var30 = false;label870: {boolean unpackWAR;File warDocBase;label871: {try {var30 = true;FileInputStream fis = new FileInputStream(contextXml);Throwable var11 = null;try {Object var12 = this.digesterLock;synchronized(this.digesterLock) {try {context = (Context)this.digester.parse(fis);} catch (Exception var49) {log.error(sm.getString("hostConfig.deployDescriptor.error", new Object[]{contextXml.getAbsolutePath()}), var49);} finally {this.digester.reset();if(context == null) {context = new FailedContext();}}}Class<?> clazz = Class.forName(this.host.getConfigClass());LifecycleListener listener = (LifecycleListener)clazz.newInstance();((Context)context).addLifecycleListener(listener);((Context)context).setConfigFile(contextXml.toURI().toURL());((Context)context).setName(cn.getName());((Context)context).setPath(cn.getPath());((Context)context).setWebappVersion(cn.getVersion());if(((Context)context).getDocBase() != null) {File docBase = new File(((Context)context).getDocBase());if(!docBase.isAbsolute()) {docBase = new File(this.host.getAppBaseFile(), ((Context)context).getDocBase());}if(!docBase.getCanonicalPath().startsWith(this.host.getAppBaseFile().getAbsolutePath() + File.separator)) {isExternal = true;deployedApp.redeployResources.put(contextXml.getAbsolutePath(), Long.valueOf(contextXml.lastModified()));deployedApp.redeployResources.put(docBase.getAbsolutePath(), Long.valueOf(docBase.lastModified()));if(docBase.getAbsolutePath().toLowerCase(Locale.ENGLISH).endsWith(".war")) {isExternalWar = true;}} else {log.warn(sm.getString("hostConfig.deployDescriptor.localDocBaseSpecified", new Object[]{docBase}));((Context)context).setDocBase((String)null);}}this.host.addChild((Container)context);} catch (Throwable var52) {var11 = var52;throw var52;} finally {if(fis != null) {if(var11 != null) {try {fis.close();} catch (Throwable var48) {var11.addSuppressed(var48);}} else {fis.close();}}}var30 = false;break label871;} catch (Throwable var54) {ExceptionUtils.handleThrowable(var54);log.error(sm.getString("hostConfig.deployDescriptor.error", new Object[]{contextXml.getAbsolutePath()}), var54);var30 = false;} finally {if(var30) {expandedDocBase = new File(this.host.getAppBaseFile(), cn.getBaseName());if(((Context)context).getDocBase() != null && !((Context)context).getDocBase().toLowerCase(Locale.ENGLISH).endsWith(".war")) {expandedDocBase = new File(((Context)context).getDocBase());if(!expandedDocBase.isAbsolute()) {expandedDocBase = new File(this.host.getAppBaseFile(), ((Context)context).getDocBase());}}boolean unpackWAR = this.unpackWARs;if(unpackWAR && context instanceof StandardContext) {unpackWAR = ((StandardContext)context).getUnpackWAR();}if(isExternalWar) {if(unpackWAR) {deployedApp.redeployResources.put(expandedDocBase.getAbsolutePath(), Long.valueOf(expandedDocBase.lastModified()));this.addWatchedResources(deployedApp, expandedDocBase.getAbsolutePath(), (Context)context);} else {this.addWatchedResources(deployedApp, (String)null, (Context)context);}} else {if(!isExternal) {File warDocBase = new File(expandedDocBase.getAbsolutePath() + ".war");if(warDocBase.exists()) {deployedApp.redeployResources.put(warDocBase.getAbsolutePath(), Long.valueOf(warDocBase.lastModified()));} else {deployedApp.redeployResources.put(warDocBase.getAbsolutePath(), Long.valueOf(0L));}}if(unpackWAR) {deployedApp.redeployResources.put(expandedDocBase.getAbsolutePath(), Long.valueOf(expandedDocBase.lastModified()));this.addWatchedResources(deployedApp, expandedDocBase.getAbsolutePath(), (Context)context);} else {this.addWatchedResources(deployedApp, (String)null, (Context)context);}if(!isExternal) {deployedApp.redeployResources.put(contextXml.getAbsolutePath(), Long.valueOf(contextXml.lastModified()));}}this.addGlobalRedeployResources(deployedApp);}}expandedDocBase = new File(this.host.getAppBaseFile(), cn.getBaseName());if(((Context)context).getDocBase() != null && !((Context)context).getDocBase().toLowerCase(Locale.ENGLISH).endsWith(".war")) {expandedDocBase = new File(((Context)context).getDocBase());if(!expandedDocBase.isAbsolute()) {expandedDocBase = new File(this.host.getAppBaseFile(), ((Context)context).getDocBase());}}unpackWAR = this.unpackWARs;if(unpackWAR && context instanceof StandardContext) {unpackWAR = ((StandardContext)context).getUnpackWAR();}if(isExternalWar) {if(unpackWAR) {deployedApp.redeployResources.put(expandedDocBase.getAbsolutePath(), Long.valueOf(expandedDocBase.lastModified()));this.addWatchedResources(deployedApp, expandedDocBase.getAbsolutePath(), (Context)context);} else {this.addWatchedResources(deployedApp, (String)null, (Context)context);}} else {if(!isExternal) {warDocBase = new File(expandedDocBase.getAbsolutePath() + ".war");if(warDocBase.exists()) {deployedApp.redeployResources.put(warDocBase.getAbsolutePath(), Long.valueOf(warDocBase.lastModified()));} else {deployedApp.redeployResources.put(warDocBase.getAbsolutePath(), Long.valueOf(0L));}}if(unpackWAR) {deployedApp.redeployResources.put(expandedDocBase.getAbsolutePath(), Long.valueOf(expandedDocBase.lastModified()));this.addWatchedResources(deployedApp, expandedDocBase.getAbsolutePath(), (Context)context);} else {this.addWatchedResources(deployedApp, (String)null, (Context)context);}if(!isExternal) {deployedApp.redeployResources.put(contextXml.getAbsolutePath(), Long.valueOf(contextXml.lastModified()));}}this.addGlobalRedeployResources(deployedApp);break label870;}expandedDocBase = new File(this.host.getAppBaseFile(), cn.getBaseName());if(((Context)context).getDocBase() != null && !((Context)context).getDocBase().toLowerCase(Locale.ENGLISH).endsWith(".war")) {expandedDocBase = new File(((Context)context).getDocBase());if(!expandedDocBase.isAbsolute()) {expandedDocBase = new File(this.host.getAppBaseFile(), ((Context)context).getDocBase());}}unpackWAR = this.unpackWARs;if(unpackWAR && context instanceof StandardContext) {unpackWAR = ((StandardContext)context).getUnpackWAR();}if(isExternalWar) {if(unpackWAR) {deployedApp.redeployResources.put(expandedDocBase.getAbsolutePath(), Long.valueOf(expandedDocBase.lastModified()));this.addWatchedResources(deployedApp, expandedDocBase.getAbsolutePath(), (Context)context);} else {this.addWatchedResources(deployedApp, (String)null, (Context)context);}} else {if(!isExternal) {warDocBase = new File(expandedDocBase.getAbsolutePath() + ".war");if(warDocBase.exists()) {deployedApp.redeployResources.put(warDocBase.getAbsolutePath(), Long.valueOf(warDocBase.lastModified()));} else {deployedApp.redeployResources.put(warDocBase.getAbsolutePath(), Long.valueOf(0L));}}if(unpackWAR) {deployedApp.redeployResources.put(expandedDocBase.getAbsolutePath(), Long.valueOf(expandedDocBase.lastModified()));this.addWatchedResources(deployedApp, expandedDocBase.getAbsolutePath(), (Context)context);} else {this.addWatchedResources(deployedApp, (String)null, (Context)context);}if(!isExternal) {deployedApp.redeployResources.put(contextXml.getAbsolutePath(), Long.valueOf(contextXml.lastModified()));}}this.addGlobalRedeployResources(deployedApp);}if(this.host.findChild(((Context)context).getName()) != null) {this.deployed.put(((Context)context).getName(), deployedApp);}if(log.isInfoEnabled()) {log.info(sm.getString("hostConfig.deployDescriptor.finished", new Object[]{contextXml.getAbsolutePath(), Long.valueOf(System.currentTimeMillis() - startTime)}));}}

ServletContext实现类为ApplicationContext。ApplicationFilterConfig负责Filter的实例化。FilterMap存储filter-mapping的配置。NamingResource存储web应用的命名服务JNDI。

StandardContext的启动过程：

发布正在启动的JMX通知，这样可以添加NotificationList来监听web应用的启动
启动当前Context维护的JNDI资源
初始化当前Context使用的WebResourceRoot并启动，WebResourceRoot维护了所有的资源集合（class文件、jar包以及其它资源文件），主要用于类加载和按照路径查找资源。
创建web应用类加载器
如果当前Context使用JNDI，则为其添加NamingContextListener
启动web应用类加载器
启用安全组件Realm
发布Configure_Start_EVENT事件
启动context子节点
启用context维护的pipeline
创建会话管理器
将context的web资源集合添加到servletContext属性，属性名为org.apache.catalina.resources。
启动添加到当前Context的ServletContaionerInitializer
实例化应用监听器
检测未覆盖的HTTP方法的安全约束
启动会话管理器
实例化FilterConfig,Filter，并调用Filter的init初始化
启动后台定时任务
发布正在运行的JMX通知
设置context状态

ContextConfig是Context的生命周期监听器

context的创建途径：

server.xml中有配置这个元素（这种方式一般不用，麻烦）
HostConfig部署web应用时，解析web应用中的META-INF/context.xml创建（没有这个目录或文件也没关系，直接自动创建）
Host部署Web应用时，解析$CATALINA_BASE/conf/Engine名/Host名目录下的context文件创建（这种方式是为设置一些第二种方式设置不了的属性用的）

context的默认配置，优先使用conf目录下的，再次是conf/eng/host/目录下的，最后是context的configfile属性。

Before_start_event事件

在context启动之前触发，用于更新context的docBase属性和解决web目录锁的问题。
更新docBase是针对本身为war包的情况，修改docbase为解压后的文件目录
具体处理过程：

根据Host的appBase以及context的docbase计算docbase的绝对路径
如果docbase是war，则先解压，然后更新docbase为解压后的位置
如果docbase是一个不存在的目录，但是存在同名war包，则解压部署、
如果docbase是一个有效目录，当时存在同名war,如果允许覆盖，则重新解压

当antiResourceLocking属性为true时，tomcat会把web包或目录复制到临时文件目录。将context的docbase更新为临时目录下的web应用。

standardWrapper的start方法广播通知了它的状态变化，然后加载了所有启动时加载的servlet。

Tomcat通过Mapper维护请求链接与Host,context,wrapper等与contaioner的映射。同时通过MapperListener监听器监听所有的Host,context，wrapper组件，在相关组件启动、停止时注册或移除相关映射。

Connector接收到请求后，首先读取请求数据，然后调用CoyoteAdapter.service()完成请求处理。

根据connector的请求和响应对象创建Servlet请求，转换请求参数并完成映射，
请求URI解码，初始化请求的路径参数，检查URI是否合法，请求映射

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