一：核心流程源码剖析

Tomcat中的各容器组件都会涉及创建、销毁等，因此设计了生命周期接口Lifecycle进行统一规范，各容 器组件实现该接口。
Lifecycle生命周期接口主要方法示意
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Lifecycle生命周期接口继承体系示意

二、核心流程源码剖析

源码追踪部分我们关注两个流程：
Tomcat启动流程和Tomcat请求处理流程 Tomcat启动流程

1、Tomcat启动流程

涉及到很多容器，初始化、启动。下面的各个容器、容器有生命周期，设计时候高端设计，都继承了Lifecycle接口，
同一管理生命周期。
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2、Tomcat请求处理流程

请求处理流程分析
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请求处理流程示意图
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3、Mapper组件体系结构

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三、点击查看源码流程

Tomcat初始化部分

参考Tomcat启动时序图来看源码

1

时序图：
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源码：
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2

时序图：
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源码：
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3、

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4、

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  1.   protected Digester createStartDigester() {
  2.         long t1=System.currentTimeMillis();
  3.         // Initialize the digester
  4.         Digester digester = new Digester();
  5.         digester.setValidating(false);
  6.         digester.setRulesValidation(true);
  7.         Map<Class<?>, List<String>> fakeAttributes = new HashMap<>();
  8.         List<String> objectAttrs = new ArrayList<>();
  9.         objectAttrs.add("className");
  10.         fakeAttributes.put(Object.class, objectAttrs);
  11.         // Ignore attribute added by Eclipse for its internal tracking
  12.         List<String> contextAttrs = new ArrayList<>();
  13.         contextAttrs.add("source");
  14.         fakeAttributes.put(StandardContext.class, contextAttrs);
  15.         digester.setFakeAttributes(fakeAttributes);
  16.         digester.setUseContextClassLoader(true);
  18.         // Configure the actions we will be using
  19.         digester.addObjectCreate("Server",
  20.                                  "org.apache.catalina.core.StandardServer",
  21.                                  "className");
  22.         digester.addSetProperties("Server");
  23.         digester.addSetNext("Server",
  24.                             "setServer",
  25.                             "org.apache.catalina.Server");
  27.         digester.addObjectCreate("Server/GlobalNamingResources",
  28.                                  "org.apache.catalina.deploy.NamingResourcesImpl");
  29.         digester.addSetProperties("Server/GlobalNamingResources");
  30.         digester.addSetNext("Server/GlobalNamingResources",
  31.                             "setGlobalNamingResources",
  32.                             "org.apache.catalina.deploy.NamingResourcesImpl");
  34.         digester.addObjectCreate("Server/Listener",
  35.                                  null, // MUST be specified in the element
  36.                                  "className");
  37.         digester.addSetProperties("Server/Listener");
  38.         digester.addSetNext("Server/Listener",
  39.                             "addLifecycleListener",
  40.                             "org.apache.catalina.LifecycleListener");
  42.         digester.addObjectCreate("Server/Service",
  43.                                  "org.apache.catalina.core.StandardService",
  44.                                  "className");
  45.         digester.addSetProperties("Server/Service");
  46.         digester.addSetNext("Server/Service",
  47.                             "addService",
  48.                             "org.apache.catalina.Service");
  50.         digester.addObjectCreate("Server/Service/Listener",
  51.                                  null, // MUST be specified in the element
  52.                                  "className");
  53.         digester.addSetProperties("Server/Service/Listener");
  54.         digester.addSetNext("Server/Service/Listener",
  55.                             "addLifecycleListener",
  56.                             "org.apache.catalina.LifecycleListener");
  58.         //Executor
  59.         digester.addObjectCreate("Server/Service/Executor",
  60.                          "org.apache.catalina.core.StandardThreadExecutor",
  61.                          "className");
  62.         digester.addSetProperties("Server/Service/Executor");
  64.         digester.addSetNext("Server/Service/Executor",
  65.                             "addExecutor",
  66.                             "org.apache.catalina.Executor");
  69.         digester.addRule("Server/Service/Connector",
  70.                          new ConnectorCreateRule());
  71.         digester.addRule("Server/Service/Connector",
  72.                          new SetAllPropertiesRule(new String[]{"executor", "sslImplementationName"}));
  73.         digester.addSetNext("Server/Service/Connector",
  74.                             "addConnector",
  75.                             "org.apache.catalina.connector.Connector");
  77.         digester.addObjectCreate("Server/Service/Connector/SSLHostConfig",
  78.                                  "org.apache.tomcat.util.net.SSLHostConfig");
  79.         digester.addSetProperties("Server/Service/Connector/SSLHostConfig");
  80.         digester.addSetNext("Server/Service/Connector/SSLHostConfig",
  81.                 "addSslHostConfig",
  82.                 "org.apache.tomcat.util.net.SSLHostConfig");
  84.         digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate",
  85.                          new CertificateCreateRule());
  86.         digester.addRule("Server/Service/Connector/SSLHostConfig/Certificate",
  87.                          new SetAllPropertiesRule(new String[]{"type"}));
  88.         digester.addSetNext("Server/Service/Connector/SSLHostConfig/Certificate",
  89.                             "addCertificate",
  90.                             "org.apache.tomcat.util.net.SSLHostConfigCertificate");
  92.         digester.addObjectCreate("Server/Service/Connector/SSLHostConfig/OpenSSLConf",
  93.                                  "org.apache.tomcat.util.net.openssl.OpenSSLConf");
  94.         digester.addSetProperties("Server/Service/Connector/SSLHostConfig/OpenSSLConf");
  95.         digester.addSetNext("Server/Service/Connector/SSLHostConfig/OpenSSLConf",
  96.                             "setOpenSslConf",
  97.                             "org.apache.tomcat.util.net.openssl.OpenSSLConf");
  99.         digester.addObjectCreate("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd",
  100.                                  "org.apache.tomcat.util.net.openssl.OpenSSLConfCmd");
  101.         digester.addSetProperties("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd");
  102.         digester.addSetNext("Server/Service/Connector/SSLHostConfig/OpenSSLConf/OpenSSLConfCmd",
  103.                             "addCmd",
  104.                             "org.apache.tomcat.util.net.openssl.OpenSSLConfCmd");
  106.         digester.addObjectCreate("Server/Service/Connector/Listener",
  107.                                  null, // MUST be specified in the element
  108.                                  "className");
  109.         digester.addSetProperties("Server/Service/Connector/Listener");
  110.         digester.addSetNext("Server/Service/Connector/Listener",
  111.                             "addLifecycleListener",
  112.                             "org.apache.catalina.LifecycleListener");
  114.         digester.addObjectCreate("Server/Service/Connector/UpgradeProtocol",
  115.                                   null, // MUST be specified in the element
  116.                                   "className");
  117.         digester.addSetProperties("Server/Service/Connector/UpgradeProtocol");
  118.         digester.addSetNext("Server/Service/Connector/UpgradeProtocol",
  119.                             "addUpgradeProtocol",
  120.                             "org.apache.coyote.UpgradeProtocol");
  122.         // Add RuleSets for nested elements
  123.         digester.addRuleSet(new NamingRuleSet("Server/GlobalNamingResources/"));
  124.         digester.addRuleSet(new EngineRuleSet("Server/Service/"));
  125.         digester.addRuleSet(new HostRuleSet("Server/Service/Engine/"));
  126.         digester.addRuleSet(new ContextRuleSet("Server/Service/Engine/Host/"));
  127.         addClusterRuleSet(digester, "Server/Service/Engine/Host/Cluster/");
  128.         digester.addRuleSet(new NamingRuleSet("Server/Service/Engine/Host/Context/"));
  130.         // When the 'engine' is found, set the parentClassLoader.
  131.         digester.addRule("Server/Service/Engine",
  132.                          new SetParentClassLoaderRule(parentClassLoader));
  133.         addClusterRuleSet(digester, "Server/Service/Engine/Cluster/");
  135.         long t2=System.currentTimeMillis();
  136.         if (log.isDebugEnabled()) {
  137.             log.debug("Digester for server.xml created " + ( t2-t1 ));
  138.         }
  139.         return digester;
  141.     }

5&6、

时序图
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源码：
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7、

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8、

时序图：
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源码：
点进services[i].init(); 也会出现7的步骤。
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9、

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12、

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13、

点击protocolHandler.init();进去
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点击进去endpoint.init();
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点击进去bind();
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Tomcat启动部分

14、

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15、

Catalina.start启动
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16、

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17、

点进getServer().start();
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18&21&22、

点进services[i].start();
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19、

点进engine.start();
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23、

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protocolHandler是一个组合组件

点进去protocolHandler.start();
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点进endpoint.start();

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点进去startAcceptorThreads();
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点进return new Acceptor();
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四、Debug断点追踪看源码流程

1、打断点

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后续的流程和点击查看的差不太多。