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Spring Boot啟動過程(六)之內(nèi)嵌Tomcat中StandardHost、StandardContext和StandardWrapper的啟動教程詳解

 更新時間:2017年04月22日 17:38:53   作者:draculav  
這篇文章主要介紹了Spring Boot啟動過程(六)之內(nèi)嵌Tomcat中StandardHost、StandardContext和StandardWrapper的啟動教程詳解,需要的朋友可以參考下

 StandardEngine[Tomcat].StandardHost[localhost]的啟動與StandardEngine不在同一個線程中,它的start:   

// Start our child containers, if any
  Container children[] = findChildren();
  List<Future<Void>> results = new ArrayList<>();
  for (int i = 0; i < children.length; i++) {
   results.add(startStopExecutor.submit(new StartChild(children[i])));
  }
  boolean fail = false;
  for (Future<Void> result : results) {
   try {
    result.get();
   } catch (Exception e) {
    log.error(sm.getString("containerBase.threadedStartFailed"), e);
    fail = true;
   }
  }
  if (fail) {
   throw new LifecycleException(
     sm.getString("containerBase.threadedStartFailed"));
  }
 private static class StartChild implements Callable<Void> {
  private Container child;
  public StartChild(Container child) {
   this.child = child;
  }
  @Override
  public Void call() throws LifecycleException {
   child.start();
   return null;
  }
 }

  這個start流程中,initInternal方法是ContainerBase的代碼,還是那個初始化startStopExecutor的,線程名例如Thread[localhost-startStop-1,5,main],這次是用來初始化host的子容器的,然后是StandardHost中的startInternal方法,主要是注冊了一個errorValue,如果現(xiàn)有的pipeline中沒有errorvalue,則反射創(chuàng)建org.apache.catalina.valves.ErrorReportValve實例,并加入pipeline中,容器pipeline加入Value時會發(fā)布一個Container.ADD_VALVE_EVENT事件,與engine一樣,之后進(jìn)入ContainerBase的startInternal,但是這次Realm是null不需要啟動,然后findChildren出StandardEngine[Tomcat]. StandardHost [localhost].StandardContext[],然后同樣新開個線程new StartChild,start同樣是上面的代碼,需要特別說明的是,這次before_init的事件有監(jiān)聽的了,F(xiàn)ixContextListener,DisablePersistSessionListener,MemoryLeakTrackingListener;FixContextListener監(jiān)聽的處理,會加入一個用于不做用戶身份認(rèn)證的安全檢查的Value:               

Context context = (Context) event.getLifecycle();
    if (event.getType().equals(Lifecycle.CONFIGURE_START_EVENT)) {
     context.setConfigured(true);
    }
    // LoginConfig is required to process @ServletSecurity
    // annotations
    if (context.getLoginConfig() == null) {
     context.setLoginConfig(
       new LoginConfig("NONE", null, null, null));
     context.getPipeline().addValve(new NonLoginAuthenticator());
    }

   DisablePersistSessionListener監(jiān)聽只處理start事件,所以這里只判斷了一下發(fā)現(xiàn)不是就出去了,其實這里可以思考下,有沒有更好的辦法,讓監(jiān)聽不只是廣播方式,能不能用訂閱方式,先不細(xì)想了,接著看代碼,MemoryLeakTrackingListener只監(jiān)聽了after_start事件,這步同樣什么都沒做。

  于是來到了StandardContext的initInternal,它的super.initInternal又是一個startStopExecutor,ContainerBase的super.initInternal就不再說了,發(fā)送j2ee.object.created消息:         

Notification notification = new Notification("j2ee.object.created",
     this.getObjectName(), sequenceNumber.getAndIncrement());
   broadcaster.sendNotification(notification);

   Notification是EventObject的子類,代表由MBean發(fā)出的通知,MBean server發(fā)出的通知會包含發(fā)出的MBean的引用,如果MBean注冊了監(jiān)聽,可以通過object name或引用獲取消息發(fā)出者,官方建議使用object name;sendNotification方法:

 /**
  * Sends a notification.
  *
  * If an {@code Executor} was specified in the constructor, it will be given one
  * task per selected listener to deliver the notification to that listener.
  *
  * @param notification The notification to send.
  */
 public void sendNotification(Notification notification) {
  if (notification == null) {
   return;
  }
  boolean enabled;
  for (ListenerInfo li : listenerList) {
   try {
    enabled = li.filter == null ||
     li.filter.isNotificationEnabled(notification);
   } catch (Exception e) {
    if (logger.debugOn()) {
     logger.debug("sendNotification", e);
    }
    continue;
   }
   if (enabled) {
    executor.execute(new SendNotifJob(notification, li));
   }
  }
 }

  發(fā)完消息就轉(zhuǎn)變狀態(tài)為初始化完成,因為監(jiān)聽器是注冊在context容器上的,于是after_init事件又觸發(fā)了那三個監(jiān)聽器,這一階段監(jiān)聽器什么都沒處理走了下過場而已;before_start同走過場;然后StandardContext的startInternal方法,發(fā)布了個j2ee.state.starting消息object name為Tomcat:j2eeType=WebModule,name=//localhost/,J2EEApplication=none, J2EEServer=none;setConfigured(false)還沒有正確的配置;設(shè)置WebResourceRoot,WebResourceRoot提供整個應(yīng)用資源處理類的各種方法,內(nèi)嵌用的實現(xiàn)類是StandardRoot,set的過程中加了寫鎖:        

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

   StandardRoot的屬性allResources:

private final List<List<WebResourceSet>> allResources =
   new ArrayList<>();
 {
  allResources.add(preResources);
  allResources.add(mainResources);
  allResources.add(classResources);
  allResources.add(jarResources);
  allResources.add(postResources);
 }

  http://tomcat.apache.org/tomcat-8.0-doc/api/org/apache/catalina/WebResourceRoot.html有相關(guān)說明,我就不翻譯了。

  set之后就是啟動resourcesStart,initInternal執(zhí)行的是StandardRoot的initInternal方法,super.initInternal中依然是那兩行代碼,register(cache, getObjectNameKeyProperties() + ",name=Cache")會發(fā)送MBeanServerNotification. REGISTRATION_NOTIFICATION通知,生成ObjectName這里cacheJmxName是Tomcat:type=WebResourceRoot,host=localhost,context=/,name=Cache;registerURLStreamHandlerFactory里面的代碼是TomcatURLStreamHandlerFactory.register()這行代碼的注釋說這是為了支持war包內(nèi)的jar資源的。之后是循環(huán)上面的allResources,init里面加入的webResourceSet,但是由于全都是空的,所以等于沒執(zhí)行,就不說了,回頭再仔細(xì)看看什么情況下回不為空,還是內(nèi)嵌的就是空的。createMainResourceSet主要是設(shè)置個主目錄,例如/tmp/tomcat-docbase.3031819619941848514.80,然后是各種資源該放在哪個子目錄的一些設(shè)置代碼;這次資源有一個了,所以可以有一個start了,DirResourceSet的;super.initInternal()的super是AbstractFileResourceSet:

 //-------------------------------------------------------- Lifecycle methods
 @Override
 protected void initInternal() throws LifecycleException {
  super.initInternal();
  // Is this an exploded web application?
  if (getWebAppMount().equals("")) {
   // Look for a manifest
   File mf = file("META-INF/MANIFEST.MF", true);
   if (mf != null && mf.isFile()) {
    try (FileInputStream fis = new FileInputStream(mf)) {
     setManifest(new Manifest(fis));
    } catch (IOException e) {
     log.warn(sm.getString("dirResourceSet.manifestFail", mf.getAbsolutePath()), e);
    }
   }
  }
 }

  super.initInternal主要是對base目錄進(jìn)行了一些規(guī)范化處理,規(guī)范的方法主要是UnixFileSystem中的canonicalize其中還使用ExpiringCache對路徑做了緩存,另外還有在normalize方法中對路徑中類似"\.."的部分做了處理。WebAppMount是Web應(yīng)用發(fā)布資源的位置,必須以‘/'開頭,這里應(yīng)該是通過它來判斷不是war包部署的模式,然后由于manifest沒找到,所以方法返回初始化完成,這個資源一路狀態(tài)變化就啟動完了。

  回到StandardRoot,接下來是processWebInfLib方法,代碼很直觀,不解釋了:

private void processWebInfLib() {
  WebResource[] possibleJars = listResources("/WEB-INF/lib", false);
  for (WebResource possibleJar : possibleJars) {
   if (possibleJar.isFile() && possibleJar.getName().endsWith(".jar")) {
    createWebResourceSet(ResourceSetType.CLASSES_JAR,
      "/WEB-INF/classes", possibleJar.getURL(), "/");
   }
  }
 }

  接下來也不解釋:

 // Need to start the newly found resources
  for (WebResourceSet classResource : classResources) {
   classResource.start();
  }

  cache.enforceObjectMaxSizeLimit是計算緩存限制的,詳細(xì)的可以參考http://tomcat.apache.org/tomcat-8.0-doc/config/resources.html,至此StandardRoot的啟動完成就只剩下改狀態(tài)了。

  回到StandardContext,因為classloader已經(jīng)有了不需要new了;接著創(chuàng)建Rfc6265CookieProcessor類型的cookieProcessor實例,關(guān)于Rfc6265標(biāo)準(zhǔn)參考http://www.rfc-editor.org/rfc/rfc6265.txt;character set mapper因為已經(jīng)初始化好了只判斷了下;工作目錄處理,先根據(jù)host和engine名生成路徑如:work/Tomcat/localhost/ROOT,結(jié)合前面的base創(chuàng)建目錄例如/tmp/tomcat.3726907762383543267.80/work/Tomcat/localhost/ROOT,然后初始化StandardContext中的ApplicationContext類型可繼承的全局變量context構(gòu)造用參數(shù)是this(context = new ApplicationContext(this)),返回new ApplicationContextFacade(this);將上面的全路徑設(shè)置給ServletContext.TEMPDIR屬性,并將這個屬性設(shè)置為只讀:

 /**
  * Set an attribute as read only.
  */
 void setAttributeReadOnly(String name) {
  if (attributes.containsKey(name))
   readOnlyAttributes.put(name, name);
 }

  之后是對擴(kuò)展進(jìn)行驗證,這里說一下,StandardContext中不管是這里的獲取資源還是之后的讀取classloader都是加了讀鎖的:

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

  catalina.useNaming用于是否開啟命名服務(wù)支持,開啟了就會注冊NamingContextListener監(jiān)聽器:

if (!dependencyCheck) {
   // do not make application available if depency 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);
   }
  }

  ClassLoader oldCCL = bindThread()里有個ThreadBindingListener,不過因為webApplicationClassLoader是null,所以等于沒執(zhí)行,返回的是null,里面的邏輯還不少,命名服務(wù)也沒開ContextBindings.bindThread于是也沒執(zhí)行。

  old的沒有,但是loader還是有的,到了loader的start了,主要要說的是WebappLoader的startInternal方法,classloader創(chuàng)建:       

 classLoader = createClassLoader();
   classLoader.setResources(context.getResources());
   classLoader.setDelegate(this.delegate);

  buildClassPath的主要功能是遍歷各個層次的classloader并將其中classpath的jar拼成一個字符串,例如
:/usr/lib/jvm/java-8-oracle/jre/lib/charsets.jar:/usr/lib/jvm/java-8-oracle/jre/lib/deploy.jar:/usr/lib/jvm/java-8-oracle/jre/lib/ext/cldrdata.jar...,是以':'作為分隔是因為我的開發(fā)環(huán)境是linux,在windows中應(yīng)該是';':

 while (loader != null) {
   if (!buildClassPath(classpath, loader)) {
    break;
   }
   loader = loader.getParent();
  }
  if (delegate) {
   // Delegation was enabled, go back and add the webapp paths
   loader = getClassLoader();
   if (loader != null) {
    buildClassPath(classpath, loader);
   }
  }

         delegate之前提過了,是會向基loader類委托的;setClassPath的最后一句:servletContext.setAttribute(Globals.CLASS_PATH_ATTR, this.classpath)。

  setPermissions方法,由于我這第一個判斷就返回了,而且看上去代碼也很直觀,我就不說了:

private void setPermissions() {
  if (!Globals.IS_SECURITY_ENABLED)
   return;
  if (context == null)
   return;
  // Tell the class loader the root of the context
  ServletContext servletContext = context.getServletContext();
  // Assigning permissions for the work directory
  File workDir =
   (File) servletContext.getAttribute(ServletContext.TEMPDIR);
  if (workDir != null) {
   try {
    String workDirPath = workDir.getCanonicalPath();
    classLoader.addPermission
     (new FilePermission(workDirPath, "read,write"));
    classLoader.addPermission
     (new FilePermission(workDirPath + File.separator + "-",
          "read,write,delete"));
   } catch (IOException e) {
    // Ignore
   }
  }
  for (URL url : context.getResources().getBaseUrls()) {
   classLoader.addPermission(url);
  }
 }

      ((Lifecycle) classLoader).start(),這個classloader是TomcatEmbeddedWebappClassLoader走的是WebappClassLoaderBase中的start方法,這里因為是內(nèi)嵌的版本(我沒確認(rèn),猜測)所以也并沒有加載到東西,所以也不細(xì)說了:

 public void start() throws LifecycleException {
  state = LifecycleState.STARTING_PREP;
  WebResource classes = resources.getResource("/WEB-INF/classes");
  if (classes.isDirectory() && classes.canRead()) {
   localRepositories.add(classes.getURL());
  }
  WebResource[] jars = resources.listResources("/WEB-INF/lib");
  for (WebResource jar : jars) {
   if (jar.getName().endsWith(".jar") && jar.isFile() && jar.canRead()) {
    localRepositories.add(jar.getURL());
    jarModificationTimes.put(
      jar.getName(), Long.valueOf(jar.getLastModified()));
   }
  }
  state = LifecycleState.STARTED;
 }

  然后生成ObjectName例如:Tomcat:context=/,host=localhost,type=TomcatEmbeddedWebappClassLoader,然后注冊MBean:getMBeanServer().registerMBean( mbean, oname);WebappLoader的start就沒什么了,started之后就是設(shè)置了幾個屬性:

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

  這里的unbindThread因為前面的bind幾乎沒做什么,所以什么也沒做;接著的bindThread主要講線程與classloader做了綁定: Thread.currentThread().setContextClassLoader (webApplicationClassLoader),至于threadBindingListener.bind()由于threadBindingListener用了個空實現(xiàn),所以這里什么也沒做。

  接下來用讀鎖取到Realm并start它;接下來發(fā)布configure_start事件,F(xiàn)ixContextListener中執(zhí)行了context.setConfigured(true)。

  終于到了StandardWrapper(StandardEngine[Tomcat].StandardHost[localhost].StandardContext[].StandardWrapper[default])的start了,initInternal直接就是ContainerBase的初始化startStopExecutor,startInternal方法是發(fā)了個j2ee.state.starting的消息,ObjectName是Tomcat:j2eeType=Servlet, WebModule=//localhost/, name=default, J2EEApplication=none, J2EEServer=none,然后又到ContainerBase的startInternal,然而由于它沒有子容器了,所以這里并沒有StartChild的任務(wù)產(chǎn)生;于是開始執(zhí)行它的Value,先start它的pipeline,startInternal方法依然是StandardPipeline的,按順序start,由于到這的時候一個都沒有,所以執(zhí)行的是basic的,StandardWrapperValve的initInternal中只有一句注釋:Don't register this Valve in JMX;startInternal的最后是threadStart,但由于backgroundProcessorDelay是-1所以并沒有啟動背景線程;setAvailable(0L)設(shè)置可用,它的說明 The date and time at which this servlet will become available (in milliseconds since the epoch), or zero if the servlet is available;然后發(fā)送一個消息j2ee.state.running,ObjectName是Tomcat:j2eeType=Servlet,WebModule=//localhost/,name=default,J2EEApplication=none,J2EEServer=none;

  StandardWrapper就啟動完了,回到StandardContext,start它的pipeline;與StandardWrapper的pipeline不同,它之前被注冊過NonLoginAuthenticator,它的startInternal方法定義在AuthenticatorBase,方法中設(shè)置了jaspicAppContextID(例如:Tomcat/localhost ),然后獲取上級容器也就是host的pipeline中的所有Value,并找到其中SingleSignOn類型的Value,明顯是用于單點登錄的,我這里沒有,于是又去找了上一級容器engine當(dāng)然還是沒有,于是就往下走了;實例化了一個StandardSessionIdGenerator,設(shè)置安全隨機(jī)數(shù)生成算法我這里是SHA1PRNG,生成器類名為null,生成器provider也是null,然后就是下一個Value對象StandardContextValve的start,只不過它的start是標(biāo)準(zhǔn)的什么額外事都沒干,于是回到了StandardContext中。下面一段主要是執(zhí)行了TomcatEmbeddedContext中的setManager方法:

@Override
 public void setManager(Manager manager) {
  if (manager instanceof ManagerBase) {
   ((ManagerBase) manager).setSessionIdGenerator(new LazySessionIdGenerator());
  }
  super.setManager(manager);
 }

  這里判斷是true,LazySessionIdGenerator整個的代碼:

class LazySessionIdGenerator extends StandardSessionIdGenerator {

@Override
 protected void startInternal() throws LifecycleException {
  setState(LifecycleState.STARTING);
 }
}

  TomcatEmbeddedContext的super.setManager(manager)的super是StandardContext,在寫鎖中執(zhí)行的,spring中多數(shù)的set都是交換的方式,先set個old保存下來,然后判斷新值和old是否相同,不相同用新的并將新值綁定容器,相同直接返回;getServletContext().setAttribute(Globals.RESOURCES_ATTR, getResources())沒什么好解釋的;setNamingResources(new NamingResourcesImpl());然后init這個namingResources,NamingResourcesImpl的initInternal,在設(shè)置當(dāng)前已知命名資源前設(shè)置resourceRequireExplicitRegistration用于避免時序問題,重復(fù)注冊是正常的,后面一段我不想解釋:

 for (ContextResource cr : resources.values()) {
   try {
    MBeanUtils.createMBean(cr);
   } catch (Exception e) {
    log.warn(sm.getString(
      "namingResources.mbeanCreateFail", cr.getName()), e);
   }
  }
  for (ContextEnvironment ce : envs.values()) {
   try {
    MBeanUtils.createMBean(ce);
   } catch (Exception e) {
    log.warn(sm.getString(
      "namingResources.mbeanCreateFail", ce.getName()), e);
   }
  }
  for (ContextResourceLink crl : resourceLinks.values()) {
   try {
    MBeanUtils.createMBean(crl);
   } catch (Exception e) {
    log.warn(sm.getString(
      "namingResources.mbeanCreateFail", crl.getName()), e);
   }
  }

        init之后是start,start中只發(fā)布了個configure_start事件。

  setInstanceManager(new DefaultInstanceManager(context, injectionMap, this, this.getClass().getClassLoader())),InstanceManager主要是用于創(chuàng)建和回收實例,然后綁定:         

 getServletContext().setAttribute(
      InstanceManager.class.getName(), getInstanceManager());
    InstanceManagerBindings.bind(getLoader().getClassLoader(), getInstanceManager());

  還有:            

 getServletContext().setAttribute(
      JarScanner.class.getName(), getJarScanner());

  合并參數(shù)mergeParameters由于我這里是空的,所以什么也沒做;然后遍歷initializers并onStartup:

  先是進(jìn)入到TomcatStarter的onStartup,這里又是:     

 for (ServletContextInitializer initializer : this.initializers) {
    initializer.onStartup(servletContext);
   }

  先是執(zhí)行:   

private org.springframework.boot.web.servlet.ServletContextInitializer getSelfInitializer() {
  return new ServletContextInitializer() {
   @Override
   public void onStartup(ServletContext servletContext) throws ServletException {
    selfInitialize(servletContext);
   }
  };
 }

  EmbeddedWebApplicationContext中的selfInitialize ,prepareEmbeddedWebApplicationContext正常情況下先打一條日志Initializing Spring embedded WebApplicationContext然后servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this)然后將this綁定servletContext,如果啟動Info級別日志,會打印類似這樣的日志:Root WebApplicationContext: initialization completed in 3150193 ms;然后new ExistingWebApplicationScopes,這玩意的注釋說它允許與非嵌入式相同的方式注冊作用域到ApplicationContextInitializer,先執(zhí)行了一個靜態(tài)代碼塊:   

 static {
   Set<String> scopes = new LinkedHashSet<String>();
   scopes.add(WebApplicationContext.SCOPE_REQUEST);//request
   scopes.add(WebApplicationContext.SCOPE_SESSION);//session
   scopes.add(WebApplicationContext.SCOPE_GLOBAL_SESSION);//global session
   SCOPES = Collections.unmodifiableSet(scopes);
  }

  但是似乎在我這add白做了,因為構(gòu)造函數(shù)中從bean工廠并沒取到Scope實例:     

this.beanFactory = beanFactory;
   for (String scopeName : SCOPES) {
    Scope scope = beanFactory.getRegisteredScope(scopeName);
    if (scope != null) {
     this.scopes.put(scopeName, scope);
    }
   }

   真正注冊作用域是在下一句WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, getServletContext()):  

 beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope());
  beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION, new SessionScope(false));
  beanFactory.registerScope(WebApplicationContext.SCOPE_GLOBAL_SESSION, new SessionScope(true));
  if (sc != null) {
   ServletContextScope appScope = new ServletContextScope(sc);
   beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION, appScope);
   // Register as ServletContext attribute, for ContextCleanupListener to detect it.
   sc.setAttribute(ServletContextScope.class.getName(), appScope);
  }
  beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory());
  beanFactory.registerResolvableDependency(ServletResponse.class, new ResponseObjectFactory());
  beanFactory.registerResolvableDependency(HttpSession.class, new SessionObjectFactory());
  beanFactory.registerResolvableDependency(WebRequest.class, new WebRequestObjectFactory());
  if (jsfPresent) {
   FacesDependencyRegistrar.registerFacesDependencies(beanFactory);
  }

  registerResolvableDependency將類型與對應(yīng)的裝配對象注冊進(jìn)bean工廠。existingScopes.restore里的代碼:      

public void restore() {
   for (Map.Entry<String, Scope> entry : this.scopes.entrySet()) {
    if (logger.isInfoEnabled()) {
     logger.info("Restoring user defined scope " + entry.getKey());
    }
    this.beanFactory.registerScope(entry.getKey(), entry.getValue());
   }
  }

  WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, getServletContext())把相應(yīng)的變量key與值注冊給bean工廠,如servletContext、contextParameters和contextAttributes;從bean工廠中獲取所有org.springframework.boot.web.servlet.ServletContextInitializer類型的bean,如filterRegistrationBean和dispatcherServletRegistration然后add給ServletContextInitializerBeans實例的initializers;addAdaptableBeans方法先從bean工廠中獲取javax.servlet.MultipartConfigElement類型的對象,然而javax.servlet.Servlet沒在bean工廠里找到,所以add什么也沒做;javax.servlet.Filter找到characterEncodingFilter、hiddenHttpMethodFilter、httpPutFormContentFilter、requestContextFilter;ServletListenerRegistrationBean.getSupportedTypes()取的是ServletListenerRegistrationBean的SUPPORTED_TYPES,不過全都沒找到,所以什么也沒做:

 static {
  Set<Class<?>> types = new HashSet<Class<?>>();
  types.add(ServletContextAttributeListener.class);
  types.add(ServletRequestListener.class);
  types.add(ServletRequestAttributeListener.class);
  types.add(HttpSessionAttributeListener.class);
  types.add(HttpSessionListener.class);
  types.add(ServletContextListener.class);
  SUPPORTED_TYPES = Collections.unmodifiableSet(types);
 }

  然后是對找到的進(jìn)行排序:     

List<ServletContextInitializer> sortedInitializers = new ArrayList<ServletContextInitializer>();
  for (Map.Entry<?, List<ServletContextInitializer>> entry : this.initializers
    .entrySet()) {
   AnnotationAwareOrderComparator.sort(entry.getValue());
   sortedInitializers.addAll(entry.getValue());
  }
  this.sortedList = Collections.unmodifiableList(sortedInitializers);
 public static void sort(Object[] array) {
  if (array.length > 1) {
   Arrays.sort(array, INSTANCE);
  }
 }
 private int doCompare(Object o1, Object o2, OrderSourceProvider sourceProvider) {
  boolean p1 = (o1 instanceof PriorityOrdered);
  boolean p2 = (o2 instanceof PriorityOrdered);
  if (p1 && !p2) {
   return -1;
  }
  else if (p2 && !p1) {
   return 1;
  }
  // Direct evaluation instead of Integer.compareTo to avoid unnecessary object creation.
  int i1 = getOrder(o1, sourceProvider);
  int i2 = getOrder(o2, sourceProvider);
  return (i1 < i2) ? -1 : (i1 > i2) ? 1 : 0;
 }

  然后對這些初始化器進(jìn)行beans.onStartup(servletContext);filterRegistrationBean執(zhí)行的AbstractFilterRegistrationBean的,主要執(zhí)行了這兩句:

        FilterRegistration.Dynamic added = servletContext.addFilter(name, filter);
                ...
        configure(added);
  name:characterEncodingFilter,filter:OrderedCharacterEncodingFilter,它的配置中這里設(shè)定了過濾器轉(zhuǎn)發(fā)模式有FORWARD、INCLUDE、REQUEST、ASYNC,攔截路徑:"/*";然后是hiddenHttpMethodFilter和OrderedHiddenHttpMethodFilter,httpPutFormContentFilter和OrderedHttpPutFormContentFilter,requestContextFilter和OrderedRequestContextFilter,cipherFilter和CipherFilter(我這自定義的)。ServletRegistrationBean的:dispatcherServlet和DispatcherServlet,asyncSupported是true,url映射是‘/',設(shè)置StandardWrapper的loadOnStartup、 multipartConfigElement。

  到了下一個初始化器SessionConfiguringInitializer:      

 public void onStartup(ServletContext servletContext) throws ServletException {
   if (this.session.getTrackingModes() != null) {
    servletContext.setSessionTrackingModes(this.session.getTrackingModes());
   }
   configureSessionCookie(servletContext.getSessionCookieConfig());
  }

  將session中的cookie信息補(bǔ)充進(jìn)ApplicationSessionCookieConfig的實例中,例如:           

 config.setName(cookie.getName());
    config.setDomain(cookie.getDomain());
    config.setPath(cookie.getPath());
    config.setComment(cookie.getComment());
    config.setHttpOnly(cookie.getHttpOnly());
    config.setSecure(cookie.getSecure());
    config.setMaxAge(cookie.getMaxAge());

  實際中我這里一個都沒執(zhí)行,因為我這的session中cookie信息都是null。

  下一個初始化器InitParameterConfiguringServletContextInitializer由于參數(shù)沒有,所以進(jìn)去就出來了。

  回到listenerStart,listenerStart:org.apache.tomcat.websocket.server.WsContextListener,用前面的DefaultInstanceManager的newInstance創(chuàng)建,然后加到lifecycleListeners中,然后傳給applicationLifecycleListenersObjects,然后是newServletContextListenerAllowed=false:當(dāng)listener發(fā)生調(diào)用后不允許添加,發(fā)布beforeContextInitialized事件,然后WsContextListener的contextInitialized:    

 ServletContext sc = sce.getServletContext();
  if(sc.getAttribute("javax.websocket.server.ServerContainer") == null) {
   WsSci.init(sce.getServletContext(), false);
  }

  init中先是初始化WsServerContainer:  

 static {
  GET_BYTES = "GET ".getBytes(StandardCharsets.ISO_8859_1);
  ROOT_URI_BYTES = "/".getBytes(StandardCharsets.ISO_8859_1);
  HTTP_VERSION_BYTES = " HTTP/1.1\r\n".getBytes(StandardCharsets.ISO_8859_1);
 }
 static {
  AUTHENTICATED_HTTP_SESSION_CLOSED = new CloseReason(CloseCodes.VIOLATED_POLICY, "This connection was established under an authenticated HTTP session that has ended.");
 }
 WsServerContainer(ServletContext servletContext) {
  this.enforceNoAddAfterHandshake = Constants.STRICT_SPEC_COMPLIANCE; //Boolean.getBoolean("org.apache.tomcat.websocket.STRICT_SPEC_COMPLIANCE")
  this.addAllowed = true;
  this.authenticatedSessions = new ConcurrentHashMap();
  this.endpointsRegistered = false;
  this.servletContext = servletContext;
   //我這里添加了org.apache.tomcat.websocket.server和本地語言en_US(我代碼是在英文版ubuntu上跑的)
  this.setInstanceManager((InstanceManager)servletContext.getAttribute(InstanceManager.class.getName())); 
  String value = servletContext.getInitParameter("org.apache.tomcat.websocket.binaryBufferSize");
  if(value != null) {
   this.setDefaultMaxBinaryMessageBufferSize(Integer.parseInt(value));
  }
  value = servletContext.getInitParameter("org.apache.tomcat.websocket.textBufferSize");
  if(value != null) {
   this.setDefaultMaxTextMessageBufferSize(Integer.parseInt(value));
  }
    //Java WebSocket 規(guī)范 1.0 并不允許第一個服務(wù)端點開始 WebSocket 握手之后進(jìn)行程序性部署。默認(rèn)情況下,Tomcat 繼續(xù)允許額外的程序性部署。
  value = servletContext.getInitParameter("org.apache.tomcat.websocket.noAddAfterHandshake");
  if(value != null) {
   this.setEnforceNoAddAfterHandshake(Boolean.parseBoolean(value));
  }
  Dynamic fr = servletContext.addFilter("Tomcat WebSocket (JSR356) Filter", new WsFilter());
  fr.setAsyncSupported(true);
  EnumSet types = EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD);
  fr.addMappingForUrlPatterns(types, true, new String[]{"/*"});
 }

  init創(chuàng)建了 WsServerContainer之后,將它設(shè)置給servletContext的javax.websocket.server.ServerContainer屬性,然后servletContext.addListener(new WsSessionListener(sc))加進(jìn)前面的applicationLifecycleListenersObjects中,init結(jié)束,回到StandardContext發(fā)布afterContextInitialized事件,我這到這里listenerStart結(jié)束。

  checkConstraintsForUncoveredMethods(findConstraints())因為我這里find出來的并沒有,所以pass;start StandardManager startInternal先是super(ManagerBase),一進(jìn)方法先是將兩個雙端隊列sessionCreationTiming和sessionExpirationTiming根據(jù)常量TIMING_STATS_CACHE_SIZE用null填滿,設(shè)置jvmRoute(jvmRoute用于區(qū)分多tomcat節(jié)點,根據(jù)jvmRoute的值來確定當(dāng)前會話屬于哪個節(jié)點 ),從engine上取得,之前設(shè)置過,getEngine: 

 public Engine getEngine() {
  Engine e = null;
  for (Container c = getContext(); e == null && c != null ; c = c.getParent()) {
   if (c instanceof Engine) {
    e = (Engine)c;
   }
  }
  return e;
 }

  set給sessionIdGenerator,將之前初始化過的一些sessionIdGenerator值set給新new的SessionIdGeneratorBase,然后start之前的sessionIdGenerator,這個start沒做什么特別的,于是回到StandardManager,加載文件(例:/tmp/tomcat.7550276477249965168.80/work/Tomcat/localhost/ROOT/SESSIONS.ser),用于session持久化的,這時候找不到的。

  filterStart對filterConfigs同步鎖,filterConfigs.put(name, filterConfig):

  loadOnStartup(findChildren()),其實都一起start過了就不用了:

   該啟動StandardContext的后天線程了super.threadStart(),當(dāng)然因為backgroundProcessorDelay所以也沒啟,unbindThread說是解綁,其實只是把classloader還原了,別的沒做什么,對應(yīng)著之前的bind。

  設(shè)置StandardContext的startTime=System.currentTimeMillis(),發(fā)j2ee.state.running的通知,ObjectName是Tomcat:J2EEApplication=none, J2EEServer=none, j2eeType=WebModule, name=//localhost/;getResources().gc()因為WebResources引用了一些jar,有些平臺可能會對jar加鎖,這里先清理,但實際上這里的實現(xiàn)是空的。

   DisablePersistSessionListener由于并沒有配置session持久化,所以會觸發(fā)這個監(jiān)聽器,實際只執(zhí)行了((StandardManager) manager).setPathname(null)。MemoryLeakTrackingListener只走了個過場。

   發(fā)布after_start事件,這回終于執(zhí)行了MemoryLeakTrackingListener:      

 if (event.getType().equals(Lifecycle.AFTER_START_EVENT)) {
    if (event.getSource() instanceof Context) {
     Context context = ((Context) event.getSource());
     childClassLoaders.put(context.getLoader().getClassLoader(),
       context.getServletContext().getContextPath());
    }
   }

  子容器就啟動完成了。

咱最近用的github:https://github.com/saaavsaaa

以上所述是小編給大家介紹的Spring Boot啟動過程(六)之內(nèi)嵌Tomcat中StandardHost、StandardContext和StandardWrapper的啟動教程詳解,希望對大家有所幫助,如果大家有任何疑問請給我留言,小編會及時回復(fù)大家的。在此也非常感謝大家對腳本之家網(wǎng)站的支持!

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