tomcat源码分析 MBeanFactory#createStandardContext过程
这个方法主要是启动一个web项目，
可以想象一下，所有跟web项目配置相关的信息，都会在这个方法里间接调用到，listener, servlet, filter等在web.xml配置的信息，还有一些通过注解配置的信息，tomcat都会扫描出来，并做初始化工作。
1、生成StandardContext实例，并设置属性。
// Create a new StandardContext instance StandardContext context = new StandardContext(); path = getPathStr(path); context.setPath(path); context.setDocBase(docBase); context.setXmlValidation(xmlValidation); context.setXmlNamespaceAware(xmlNamespaceAware); context.setTldValidation(tldValidation); context.setTldNamespaceAware(tldNamespaceAware);
2、生成ContextConfig实例。ContextConfig实现了LifecycleListener接口，该接口最重要的方法是
public void lifecycleEvent(LifecycleEvent event);
在ContextConfig实现这个方法，并注册到StandardContext上，对StandardContext实例触发的一些重要事件做出回应。
ContextConfig contextConfig = new ContextConfig(); context.addLifecycleListener(contextConfig);
3、设置StandardContext的config属性，即根据哪个配置文件加载这个项目的。
在我这个环境下是：file:/....../conf/Catalina/localhost/ROOT.xml
4、以MBean的方式调用HostConfig的manageApp方法，参数即为StandardContext实例。
这一步将StandardContext添加到Host上，
host.addChild(context);
5、在addChild过程中，将调用StandardContext的startInternal进行初始化工作。
/** * Start this component and implement the requirements * of {@link org.apache.catalina.util.LifecycleBase#startInternal()}. * * @exception LifecycleException if this component detects a fatal error * that prevents this component from being used */ @Override 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(); } // Add missing components as necessary if (webappResources == null) { // (1) Required by Loader if (log.isDebugEnabled()) log.debug("Configuring default Resources"); try { if ((getDocBase() != null) && (getDocBase().endsWith(".war")) && (!(new File(getBasePath())).isDirectory())) setResources(new WARDirContext()); else setResources(new FileDirContext()); } catch (IllegalArgumentException e) { log.error("Error initializing resources: " + e.getMessage()); ok = false; } } if (ok) { if (!resourcesStart()) { log.error( "Error in resourceStart()"); ok = false; } } if (getLoader() == null) { WebappLoader webappLoader = new WebappLoader(getParentClassLoader()); webappLoader.setDelegate(getDelegate()); setLoader(webappLoader); } // Initialize character set mapper getCharsetMapper(); // Post work directory postWorkDirectory(); // Validate required extensions boolean dependencyCheck = true; try { dependencyCheck = ExtensionValidator.validateApplication (getResources(), this); } catch (IOException ioe) { log.error("Error in dependencyCheck", ioe); dependencyCheck = false; } 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); } } // 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 if ((loader != null) && (loader instanceof Lifecycle)) ((Lifecycle) loader).start(); // since the loader just started, the webapp classloader is now // created. // 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(); if ((cluster != null) && (cluster instanceof Lifecycle)) ((Lifecycle) cluster).start(); Realm realm = getRealmInternal(); if ((realm != null) && (realm instanceof Lifecycle)) ((Lifecycle) realm).start(); if ((resources != null) && (resources instanceof Lifecycle)) ((Lifecycle) resources).start(); // Notify our interested LifecycleListeners fireLifecycleEvent(Lifecycle.CONFIGURE_START_EVENT, null); // Start our child containers, if not already started 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(); } // Acquire clustered manager Manager contextManager = null; if (manager == null) { if (log.isDebugEnabled()) { log.debug(sm.getString("standardContext.cluster.noManager", Boolean.valueOf((getCluster() != null)), Boolean.valueOf(distributable))); } if ( (getCluster() != null) && distributable) { try { contextManager = getCluster().createManager(getName()); } catch (Exception ex) { log.error("standardContext.clusterFail", ex); ok = false; } } else { contextManager = new StandardManager(); } } // Configure default manager if none was specified if (contextManager != null) { if (log.isDebugEnabled()) { log.debug(sm.getString("standardContext.manager", contextManager.getClass().getName())); } setManager(contextManager); } if (manager!=null && (getCluster() != null) && distributable) { //let the cluster know that there is a context that is distributable //and that it has its own manager getCluster().registerManager(manager); } } } finally { // Unbinding thread unbindThread(oldCCL); } if (!getConfigured()) { log.error( "Error getConfigured"); ok = false; } // We put the resources into the servlet context if (ok) getServletContext().setAttribute (Globals.RESOURCES_ATTR, getResources()); // Initialize associated mapper mapper.setContext(getPath(), welcomeFiles, resources); // Binding thread oldCCL = bindThread(); if (ok ) { if (getInstanceManager() == null) { javax.naming.Context context = null; if (isUseNaming() && getNamingContextListener() != null) { context = getNamingContextListener().getEnvContext(); } Map<String, Map<String, String>> injectionMap = buildInjectionMap( getIgnoreAnnotations() ? new NamingResources(): getNamingResources()); setInstanceManager(new DefaultInstanceManager(context, injectionMap, this, this.getClass().getClassLoader())); getServletContext().setAttribute( InstanceManager.class.getName(), getInstanceManager()); } } try { // Create context attributes that will be required if (ok) { getServletContext().setAttribute( JarScanner.class.getName(), getJarScanner()); } // Set up the context init params mergeParameters(); // Call ServletContainerInitializers for (Map.Entry<ServletContainerInitializer, Set<Class<?>>> entry : initializers.entrySet()) { try { entry.getKey().onStartup(entry.getValue(), getServletContext()); } catch (ServletException e) { // TODO: Log error ok = false; break; } } // Configure and call application event listeners if (ok) { if (!listenerStart()) { log.error( "Error listenerStart"); ok = false; } } try { // Start manager if ((manager != null) && (manager instanceof Lifecycle)) { ((Lifecycle) getManager()).start(); } // Start ContainerBackgroundProcessor thread super.threadStart(); } catch(Exception e) { log.error("Error manager.start()", e); ok = false; } // Configure and call application filters if (ok) { if (!filterStart()) { log.error("Error filterStart"); ok = false; } } // Load and initialize all "load on startup" servlets if (ok) { loadOnStartup(findChildren()); } } finally { // Unbinding thread unbindThread(oldCCL); } // Set available status depending upon startup success if (ok) { if (log.isDebugEnabled()) log.debug("Starting completed"); } else { log.error(sm.getString("standardContext.startFailed", getName())); } startTime=System.currentTimeMillis(); // Send j2ee.state.running notification if (ok && (this.getObjectName() != null)) { Notification notification = new Notification("j2ee.state.running", this.getObjectName(), sequenceNumber.getAndIncrement()); broadcaster.sendNotification(notification); } // Close all JARs right away to avoid always opening a peak number // of files on startup if (getLoader() instanceof WebappLoader) { ((WebappLoader) getLoader()).closeJARs(true); } // Reinitializing if something went wrong if (!ok) { setState(LifecycleState.FAILED); } else { setState(LifecycleState.STARTING); } }
这一步做了太多工作，接下来我们再做一些分析工作。
