tomcat8.5.57源码阅读笔记4.1

接着上一篇, 该到StandardContext的 init 和 startInternal 方法了.

StandardContext#initInternal()

此方法由 org.apache.catalina.util.LifecycleBase#init() 调用而来.

//org.apache.catalina.core.StandardContext#initInternal
protected void initInternal() throws LifecycleException {
    super.initInternal();

    // Register the naming resources
    if (namingResources != null) {
        namingResources.init();
    }

    // Send j2ee.object.created notification
    if (this.getObjectName() != null) {
        Notification notification = new Notification("j2ee.object.created",
                this.getObjectName(), sequenceNumber.getAndIncrement());
        broadcaster.sendNotification(notification);
    }
}

super.initInternal() 调用的是 org.apache.catalina.core.ContainerBase#initInternal(), 里面创建了一个阻塞队列线程池

StandardContext#startInternal

protected synchronized void startInternal() throws LifecycleException {
        if(log.isDebugEnabled())
            log.debug("Starting " + getBaseName());

        // Send j2ee.state.starting notification
        if (this.getObjectName() != null) {
            Notification notification = new Notification("j2ee.state.starting",
                    this.getObjectName(), sequenceNumber.getAndIncrement());
            broadcaster.sendNotification(notification);
        }

        setConfigured(false);
        boolean ok = true;

        // Currently this is effectively a NO-OP but needs to be called to
        // ensure the NamingResources follows the correct lifecycle
        if (namingResources != null) {
            namingResources.start();
        }

        // Post work directory
        // 生成工作目录, work/Catalina/localhost
        postWorkDirectory();

        // Add missing components as necessary
        if (getResources() == null) {   // (1) Required by Loader
            if (log.isDebugEnabled())
                log.debug("Configuring default Resources");

            try {
                setResources(new StandardRoot(this));
            } catch (IllegalArgumentException e) {
                log.error(sm.getString("standardContext.resourcesInit"), e);
                ok = false;
            }
        }
        if (ok) {
            resourcesStart();
        }

        if (getLoader() == null) {
            WebappLoader webappLoader = new WebappLoader();
            webappLoader.setDelegate(getDelegate());
            setLoader(webappLoader);
        }

        // An explicit cookie processor hasn't been specified; use the default
        if (cookieProcessor == null) {
            cookieProcessor = new Rfc6265CookieProcessor();
        }

        // Initialize character set mapper
        // 字符集映射
        getCharsetMapper();

        // Validate required extensions
        boolean dependencyCheck = true;
        try {
            dependencyCheck = ExtensionValidator.validateApplication
                (getResources(), this);
        } catch (IOException ioe) {
            log.error(sm.getString("standardContext.extensionValidationError"), ioe);
            dependencyCheck = false;
        }

        if (!dependencyCheck) {
            // do not make application available if dependency check fails
            ok = false;
        }

        // Reading the "catalina.useNaming" environment variable
        String useNamingProperty = System.getProperty("catalina.useNaming");
        if ((useNamingProperty != null)
            && (useNamingProperty.equals("false"))) {
            useNaming = false;
        }

        if (ok && isUseNaming()) {
            if (getNamingContextListener() == null) {
                NamingContextListener ncl = new NamingContextListener();
                ncl.setName(getNamingContextName());
                ncl.setExceptionOnFailedWrite(getJndiExceptionOnFailedWrite());
                addLifecycleListener(ncl);
                setNamingContextListener(ncl);
            }
        }

        // Standard container startup
        if (log.isDebugEnabled())
            log.debug("Processing standard container startup");


        // Binding thread
        ClassLoader oldCCL = bindThread();

        try {
            if (ok) {
                // Start our subordinate components, if any
                Loader loader = getLoader();
                if (loader instanceof Lifecycle) {
                    ((Lifecycle) loader).start();
                }

                // since the loader just started, the webapp classloader is now
                // created.
                setClassLoaderProperty("clearReferencesRmiTargets",
                        getClearReferencesRmiTargets());
                setClassLoaderProperty("clearReferencesStopThreads",
                        getClearReferencesStopThreads());
                setClassLoaderProperty("clearReferencesStopTimerThreads",
                        getClearReferencesStopTimerThreads());
                setClassLoaderProperty("clearReferencesHttpClientKeepAliveThread",
                        getClearReferencesHttpClientKeepAliveThread());
                setClassLoaderProperty("clearReferencesObjectStreamClassCaches",
                        getClearReferencesObjectStreamClassCaches());
                setClassLoaderProperty("clearReferencesThreadLocals",
                        getClearReferencesThreadLocals());

                // By calling unbindThread and bindThread in a row, we setup the
                // current Thread CCL to be the webapp classloader
                unbindThread(oldCCL);
                oldCCL = bindThread();

                // Initialize logger again. Other components might have used it
                // too early, so it should be reset.
                logger = null;
                getLogger();

                Realm realm = getRealmInternal();
                if(null != realm) {
                    if (realm instanceof Lifecycle) {
                        ((Lifecycle) realm).start();
                    }

                    // Place the CredentialHandler into the ServletContext so
                    // applications can have access to it. Wrap it in a "safe"
                    // handler so application's can't modify it.
                    CredentialHandler safeHandler = new CredentialHandler() {
                        @Override
                        public boolean matches(String inputCredentials, String storedCredentials) {
                            return getRealmInternal().getCredentialHandler().matches(inputCredentials, storedCredentials);
                        }

                        @Override
                        public String mutate(String inputCredentials) {
                            return getRealmInternal().getCredentialHandler().mutate(inputCredentials);
                        }
                    };
                    context.setAttribute(Globals.CREDENTIAL_HANDLER, safeHandler);
                }

                // Notify our interested LifecycleListeners
                // 这里会激发监听器 ContextConfig
                fireLifecycleEvent(Lifecycle.CONFIGURE_START_EVENT, null);

                // Start our child containers, if not already started 如果Wrapper没启动, 这里会再次尝试启动
                for (Container child : findChildren()) {
                    if (!child.getState().isAvailable()) {
                        child.start();
                    }
                }

                // Start the Valves in our pipeline (including the basic),
                // if any
                if (pipeline instanceof Lifecycle) {
                    ((Lifecycle) pipeline).start();
                }

                ......
    }

2. 这个方法里面会调用 loadOnStartup(findChildren()) 方法, 当 loadOnStartup >=0 时, 会对wrapper进行load操作, 最终执行 servlet#init() 方法.

1. fireLifecycleEvent 会激发 ContextConfig 的监听方法: org.apache.catalina.startup.ContextConfig#lifecycleEvent

套路和 HostConfig 是一样的.

public void lifecycleEvent(LifecycleEvent event) {

    // Identify the context we are associated with
    try {
        context = (Context) event.getLifecycle();
    } catch (ClassCastException e) {
        log.error(sm.getString("contextConfig.cce", event.getLifecycle()), e);
        return;
    }

    // Process the event that has occurred
    if (event.getType().equals(Lifecycle.CONFIGURE_START_EVENT)) {
        configureStart();
    } else if (event.getType().equals(Lifecycle.BEFORE_START_EVENT)) {
        beforeStart();
    } else if (event.getType().equals(Lifecycle.AFTER_START_EVENT)) {
        // Restore docBase for management tools
        if (originalDocBase != null) {
            context.setDocBase(originalDocBase);
        }
    } else if (event.getType().equals(Lifecycle.CONFIGURE_STOP_EVENT)) {
        configureStop();
    } else if (event.getType().equals(Lifecycle.AFTER_INIT_EVENT)) {
        init();
    } else if (event.getType().equals(Lifecycle.AFTER_DESTROY_EVENT)) {
        destroy();
    }
}

根据传入事件, 会进入 configureStart() 方法.

protected synchronized void configureStart() {
    // Called from StandardContext.start()

    if (log.isDebugEnabled()) {
        log.debug(sm.getString("contextConfig.start"));
    }

    if (log.isDebugEnabled()) {
        log.debug(sm.getString("contextConfig.xmlSettings",
                context.getName(),
                Boolean.valueOf(context.getXmlValidation()),
                Boolean.valueOf(context.getXmlNamespaceAware())));
    }

    //解析 web.xml
    webConfig();

    //后加代码， 为了解决报错问题
    context.addServletContainerInitializer(new JasperInitializer(), null);

    if (!context.getIgnoreAnnotations()) {
        applicationAnnotationsConfig();
    }
    if (ok) {
        validateSecurityRoles();
    }

    // Configure an authenticator if we need one
    if (ok) {
        authenticatorConfig();
    }

    // Dump the contents of this pipeline if requested
    if (log.isDebugEnabled()) {
        log.debug("Pipeline Configuration:");
        Pipeline pipeline = context.getPipeline();
        Valve valves[] = null;
        if (pipeline != null) {
            valves = pipeline.getValves();
        }
        if (valves != null) {
            for (Valve valve : valves) {
                log.debug("  " + valve.getClass().getName());
            }
        }
        log.debug("======================");
    }

    // Make our application available if no problems were encountered
    if (ok) {
        context.setConfigured(true);
    } else {
        log.error(sm.getString("contextConfig.unavailable"));
        context.setConfigured(false);
    }

}

webConfig()方法, 会去解析 web.xml 文件. servlet3.0之前, 都是将 servlet 配置在web.xml文件中, servlet3.0之后, 出现了注解的方式.

protected void webConfig() {
    //web.xml解析器
    WebXmlParser webXmlParser = new WebXmlParser(context.getXmlNamespaceAware(),
            context.getXmlValidation(), context.getXmlBlockExternal());

    Set<WebXml> defaults = new HashSet<>();
    defaults.add(getDefaultWebXmlFragment(webXmlParser));

    //web.xml解析结果, 放到 WebXml 对象中
    WebXml webXml = createWebXml();

    // Parse context level web.xml
    InputSource contextWebXml = getContextWebXmlSource();
    if (!webXmlParser.parseWebXml(contextWebXml, webXml, false)) {
        ok = false;
    }

    ServletContext sContext = context.getServletContext();

    // Ordering is important here

    // Step 1. Identify all the JARs packaged with the application and those
    // provided by the container. If any of the application JARs have a
    // web-fragment.xml it will be parsed at this point. web-fragment.xml
    // files are ignored for container provided JARs.
    Map<String,WebXml> fragments = processJarsForWebFragments(webXml, webXmlParser);

    // Step 2. Order the fragments.
    Set<WebXml> orderedFragments = null;
    orderedFragments = WebXml.orderWebFragments(webXml, fragments, sContext);

    // Step 3. Look for ServletContainerInitializer implementations
    if (ok) {
        processServletContainerInitializers();
    }

    if  (!webXml.isMetadataComplete() || typeInitializerMap.size() > 0) {
        // Steps 4 & 5.
        processClasses(webXml, orderedFragments);
    }

    if (!webXml.isMetadataComplete()) {
        ......
    } else {
        webXml.merge(defaults);
        convertJsps(webXml);
        //配置方法, 会调用 context.addChild()方法
        configureContext(webXml);
    }

    ......
}

进 configureContext() 方法看

private void configureContext(WebXml webxml) {
    // As far as possible, process in alphabetical order so it is easy to
    // check everything is present
    // Some validation depends on correct public ID
    context.setPublicId(webxml.getPublicId());

    // Everything else in order
    context.setEffectiveMajorVersion(webxml.getMajorVersion());
    context.setEffectiveMinorVersion(webxml.getMinorVersion());

    for (Entry<String, String> entry : webxml.getContextParams().entrySet()) {
        context.addParameter(entry.getKey(), entry.getValue());
    }
    context.setDenyUncoveredHttpMethods(
            webxml.getDenyUncoveredHttpMethods());
    context.setDisplayName(webxml.getDisplayName());
    context.setDistributable(webxml.isDistributable());
    for (ContextLocalEjb ejbLocalRef : webxml.getEjbLocalRefs().values()) {
        context.getNamingResources().addLocalEjb(ejbLocalRef);
    }
    for (ContextEjb ejbRef : webxml.getEjbRefs().values()) {
        context.getNamingResources().addEjb(ejbRef);
    }
    for (ContextEnvironment environment : webxml.getEnvEntries().values()) {
        context.getNamingResources().addEnvironment(environment);
    }
    for (ErrorPage errorPage : webxml.getErrorPages().values()) {
        context.addErrorPage(errorPage);
    }
    for (FilterDef filter : webxml.getFilters().values()) {
        if (filter.getAsyncSupported() == null) {
            filter.setAsyncSupported("false");
        }
        context.addFilterDef(filter);
    }
    for (FilterMap filterMap : webxml.getFilterMappings()) {
        context.addFilterMap(filterMap);
    }
    context.setJspConfigDescriptor(webxml.getJspConfigDescriptor());
    for (String listener : webxml.getListeners()) {
        context.addApplicationListener(listener);
    }
    for (Entry<String, String> entry :
            webxml.getLocaleEncodingMappings().entrySet()) {
        context.addLocaleEncodingMappingParameter(entry.getKey(),
                entry.getValue());
    }
    // Prevents IAE
    if (webxml.getLoginConfig() != null) {
        context.setLoginConfig(webxml.getLoginConfig());
    }
    for (MessageDestinationRef mdr :
            webxml.getMessageDestinationRefs().values()) {
        context.getNamingResources().addMessageDestinationRef(mdr);
    }

    // messageDestinations were ignored in Tomcat 6, so ignore here

    context.setIgnoreAnnotations(webxml.isMetadataComplete());
    for (Entry<String, String> entry :
            webxml.getMimeMappings().entrySet()) {
        context.addMimeMapping(entry.getKey(), entry.getValue());
    }
    // Name is just used for ordering
    for (ContextResourceEnvRef resource :
            webxml.getResourceEnvRefs().values()) {
        context.getNamingResources().addResourceEnvRef(resource);
    }
    for (ContextResource resource : webxml.getResourceRefs().values()) {
        context.getNamingResources().addResource(resource);
    }
    boolean allAuthenticatedUsersIsAppRole =
            webxml.getSecurityRoles().contains(
                    SecurityConstraint.ROLE_ALL_AUTHENTICATED_USERS);
    for (SecurityConstraint constraint : webxml.getSecurityConstraints()) {
        if (allAuthenticatedUsersIsAppRole) {
            constraint.treatAllAuthenticatedUsersAsApplicationRole();
        }
        context.addConstraint(constraint);
    }
    for (String role : webxml.getSecurityRoles()) {
        context.addSecurityRole(role);
    }
    for (ContextService service : webxml.getServiceRefs().values()) {
        context.getNamingResources().addService(service);
    }
    for (ServletDef servlet : webxml.getServlets().values()) {
        Wrapper wrapper = context.createWrapper();
        // Description is ignored
        // Display name is ignored
        // Icons are ignored

        // jsp-file gets passed to the JSP Servlet as an init-param

        if (servlet.getLoadOnStartup() != null) {
            wrapper.setLoadOnStartup(servlet.getLoadOnStartup().intValue());
        }
        if (servlet.getEnabled() != null) {
            wrapper.setEnabled(servlet.getEnabled().booleanValue());
        }
        wrapper.setName(servlet.getServletName());
        Map<String,String> params = servlet.getParameterMap();
        for (Entry<String, String> entry : params.entrySet()) {
            wrapper.addInitParameter(entry.getKey(), entry.getValue());
        }
        wrapper.setRunAs(servlet.getRunAs());
        Set<SecurityRoleRef> roleRefs = servlet.getSecurityRoleRefs();
        for (SecurityRoleRef roleRef : roleRefs) {
            wrapper.addSecurityReference(
                    roleRef.getName(), roleRef.getLink());
        }
        wrapper.setServletClass(servlet.getServletClass());
        MultipartDef multipartdef = servlet.getMultipartDef();
        if (multipartdef != null) {
            long maxFileSize = -1;
            long maxRequestSize = -1;
            int fileSizeThreshold = 0;

            if(null != multipartdef.getMaxFileSize()) {
                maxFileSize = Long.parseLong(multipartdef.getMaxFileSize());
            }
            if(null != multipartdef.getMaxRequestSize()) {
                maxRequestSize = Long.parseLong(multipartdef.getMaxRequestSize());
            }
            if(null != multipartdef.getFileSizeThreshold()) {
                fileSizeThreshold = Integer.parseInt(multipartdef.getFileSizeThreshold());
            }

            wrapper.setMultipartConfigElement(new MultipartConfigElement(
                    multipartdef.getLocation(),
                    maxFileSize,
                    maxRequestSize,
                    fileSizeThreshold));
        }
        if (servlet.getAsyncSupported() != null) {
            wrapper.setAsyncSupported(
                    servlet.getAsyncSupported().booleanValue());
        }
        wrapper.setOverridable(servlet.isOverridable());
        //加入节点Servlet StandardContext#addChild(StandardWrapper)
        context.addChild(wrapper);
    }
    for (Entry<String, String> entry :
            webxml.getServletMappings().entrySet()) {
        context.addServletMappingDecoded(entry.getKey(), entry.getValue());
    }
    SessionConfig sessionConfig = webxml.getSessionConfig();
    if (sessionConfig != null) {
        if (sessionConfig.getSessionTimeout() != null) {
            context.setSessionTimeout(
                    sessionConfig.getSessionTimeout().intValue());
        }
        SessionCookieConfig scc =
            context.getServletContext().getSessionCookieConfig();
        scc.setName(sessionConfig.getCookieName());
        scc.setDomain(sessionConfig.getCookieDomain());
        scc.setPath(sessionConfig.getCookiePath());
        scc.setComment(sessionConfig.getCookieComment());
        if (sessionConfig.getCookieHttpOnly() != null) {
            scc.setHttpOnly(sessionConfig.getCookieHttpOnly().booleanValue());
        }
        if (sessionConfig.getCookieSecure() != null) {
            scc.setSecure(sessionConfig.getCookieSecure().booleanValue());
        }
        if (sessionConfig.getCookieMaxAge() != null) {
            scc.setMaxAge(sessionConfig.getCookieMaxAge().intValue());
        }
        if (sessionConfig.getSessionTrackingModes().size() > 0) {
            context.getServletContext().setSessionTrackingModes(
                    sessionConfig.getSessionTrackingModes());
        }
    }

    // Context doesn't use version directly

    for (String welcomeFile : webxml.getWelcomeFiles()) {
        /*
         * The following will result in a welcome file of "" so don't add
         * that to the context
         * <welcome-file-list>
         *   <welcome-file/>
         * </welcome-file-list>
         */
        if (welcomeFile != null && welcomeFile.length() > 0) {
            context.addWelcomeFile(welcomeFile);
        }
    }

    // Do this last as it depends on servlets
    for (JspPropertyGroup jspPropertyGroup :
            webxml.getJspPropertyGroups()) {
        String jspServletName = context.findServletMapping("*.jsp");
        if (jspServletName == null) {
            jspServletName = "jsp";
        }
        if (context.findChild(jspServletName) != null) {
            for (String urlPattern : jspPropertyGroup.getUrlPatterns()) {
                context.addServletMappingDecoded(urlPattern, jspServletName, true);
            }
        } else {
            if(log.isDebugEnabled()) {
                for (String urlPattern : jspPropertyGroup.getUrlPatterns()) {
                    log.debug("Skipping " + urlPattern + " , no servlet " +
                            jspServletName);
                }
            }
        }
    }

    for (Entry<String, String> entry :
            webxml.getPostConstructMethods().entrySet()) {
        context.addPostConstructMethod(entry.getKey(), entry.getValue());
    }

    for (Entry<String, String> entry :
        webxml.getPreDestroyMethods().entrySet()) {
        context.addPreDestroyMethod(entry.getKey(), entry.getValue());
    }
}

1. 对 Context 设置了一些属性, 如过滤器, 错误页等

2. 创建 Wrapper , 并设置一些属性, 如 LoadOnStartup

3. 通过 context.addChild(wrapper), 将 servlet 加入到 context 的子节点上.

StandardContext.addChild()

public void addChild(Container child) {

    // Global JspServlet
    Wrapper oldJspServlet = null;

    if (!(child instanceof Wrapper)) {
        throw new IllegalArgumentException
            (sm.getString("standardContext.notWrapper"));
    }

    boolean isJspServlet = "jsp".equals(child.getName());

    // Allow webapp to override JspServlet inherited from global web.xml.
    if (isJspServlet) {
        oldJspServlet = (Wrapper) findChild("jsp");
        if (oldJspServlet != null) {
            removeChild(oldJspServlet);
        }
    }

    super.addChild(child);

    if (isJspServlet && oldJspServlet != null) {
        /*
         * The webapp-specific JspServlet inherits all the mappings
         * specified in the global web.xml, and may add additional ones.
         */
        String[] jspMappings = oldJspServlet.findMappings();
        for (int i=0; jspMappings!=null && i<jspMappings.length; i++) {
            addServletMappingDecoded(jspMappings[i], child.getName());
        }
    }
}

这里的 super.addChild(child) 和 StandardHost里面, 调用的 super.addChild() 是一样的.

@Override
public void addChild(Container child) {
    if (Globals.IS_SECURITY_ENABLED) {
        PrivilegedAction<Void> dp =
            new PrivilegedAddChild(child);
        AccessController.doPrivileged(dp);
    } else {
        addChildInternal(child);
    }
}


//在解析 Server.xml 文件的时候, 通过 StandardEngine.addChild() 一路调用过来
//<Host name="localhost"  appBase="webapps" unpackWARs="true" autoDeploy="true" startStopThreads="1">
//此时, 不会调用 start() 方法
private void addChildInternal(Container child) {

    if( log.isDebugEnabled() )
        log.debug("Add child " + child + " " + this);
    synchronized(children) {
        if (children.get(child.getName()) != null)
            throw new IllegalArgumentException("addChild:  Child name '" +
                                               child.getName() +
                                               "' is not unique");
        child.setParent(this);  // May throw IAE
        children.put(child.getName(), child);
    }

    // Start child
    // Don't do this inside sync block - start can be a slow process and
    // locking the children object can cause problems elsewhere
    try {
        if ((getState().isAvailable() ||
                LifecycleState.STARTING_PREP.equals(getState())) &&
                startChildren) {
            //addChild的时候, 调用启动方法, 解析Server.xml时, 不会进此方法
            //如果子类没有重写start方法, 则会调用 LifecycleBase#start()
            //StandardHost的时候, 会进此方法, 调用的是 StandardContext.start() -> StandardContext.startInternal()
            //StandardContext的时候, 会进此方法, 调用的是 StandardWrapper.start() -> StandardWrapper.startInternal()
            child.start();
        }
    } catch (LifecycleException e) {
        log.error("ContainerBase.addChild: start: ", e);
        throw new IllegalStateException("ContainerBase.addChild: start: " + e);
    } finally {
        fireContainerEvent(ADD_CHILD_EVENT, child);
    }
}

 由于 StandardWrapper 没有重写 start() 方法, 所以会调用 LifecycleBase#start()

public final synchronized void start() throws LifecycleException {

    if (LifecycleState.STARTING_PREP.equals(state) || LifecycleState.STARTING.equals(state) ||
            LifecycleState.STARTED.equals(state)) {

        if (log.isDebugEnabled()) {
            Exception e = new LifecycleException();
            log.debug(sm.getString("lifecycleBase.alreadyStarted", toString()), e);
        } else if (log.isInfoEnabled()) {
            log.info(sm.getString("lifecycleBase.alreadyStarted", toString()));
        }

        return;
    }

    if (state.equals(LifecycleState.NEW)) {
        //results.add(startStopExecutor.submit(new StartChild(child)));
        //异步执行 StandardHost.start() 方法时, 会走这里
        init();
    } else if (state.equals(LifecycleState.FAILED)) {
        stop();
    } else if (!state.equals(LifecycleState.INITIALIZED) &&
            !state.equals(LifecycleState.STOPPED)) {
        invalidTransition(Lifecycle.BEFORE_START_EVENT);
    }

    try {
        setStateInternal(LifecycleState.STARTING_PREP, null, false);
        startInternal();
        if (state.equals(LifecycleState.FAILED)) {
            // This is a 'controlled' failure. The component put itself into the
            // FAILED state so call stop() to complete the clean-up.
            stop();
        } else if (!state.equals(LifecycleState.STARTING)) {
            // Shouldn't be necessary but acts as a check that sub-classes are
            // doing what they are supposed to.
            invalidTransition(Lifecycle.AFTER_START_EVENT);
        } else {
            setStateInternal(LifecycleState.STARTED, null, false);
        }
    } catch (Throwable t) {
        // This is an 'uncontrolled' failure so put the component into the
        // FAILED state and throw an exception.
        handleSubClassException(t, "lifecycleBase.startFail", toString());
    }
}

StandardWrapper中, 没有重写 initInternal(), 所以会调用 org.apache.catalina.core.ContainerBase#initInternal(), 创建一个阻塞队列线程池

所以, 这里只需要看 startInternal() 方法即可

StandardWrapper#startInternal()

protected synchronized void startInternal() throws LifecycleException {

    // Send j2ee.state.starting notification
    if (this.getObjectName() != null) {
        Notification notification = new Notification("j2ee.state.starting",
                                                    this.getObjectName(),
                                                    sequenceNumber++);
        broadcaster.sendNotification(notification);
    }

    // Start up this component
    super.startInternal();

    setAvailable(0L);

    // Send j2ee.state.running notification
    if (this.getObjectName() != null) {
        Notification notification =
            new Notification("j2ee.state.running", this.getObjectName(),
                            sequenceNumber++);
        broadcaster.sendNotification(notification);
    }

}

StandardWrapper#startInternal() 到这里就完结了, 因为他是Servlet, 是最后一级, 所以也没有子节点了.