1 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>tomcat load web.xml>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 2     3     4     5    tomcat加载web.xml中用户的servlet到context中去，同时实例化该servlet到/WEB-INF/classes/中 6    过程大致如下 7     8    由事件接收器 接收 到CONFIGURE_START_EVENT的消息后，才会触发处理加载web.xml的动作， 9    10            /**11              * The LifecycleEvent type for the "configure_start" event. Used by those12              * components that use a separate component to perform configuration and13              * need to signal when configuration should be performed - usually after14              * {@link #BEFORE_START_EVENT} and before {@link #START_EVENT}.15              */16             public static final String CONFIGURE_START_EVENT = "configure_start";17     18    那么又是谁来把该消息注册到监听器中的呢？如下，从启动过程中进行查找：19    20   21  org.apache.catalina.startup.Bootstrap.start()22   -->org.apache.catalina.startup.Catalina.start()23   ----》load()24   ------》25      getServer().init();26      Server==="org.apache.catalina.core.StandardServer" 27      -----》StandardServer.initInternal()28        StandardServer.startInternal() 29              ---》30                     void java.org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(String type, Object data)31                              32                             fireLifecycleEvent(CONFIGURE_START_EVENT, null);33                              ---》34                              LifecycleSupport fireLifecycleEvent(CONFIGURE_START_EVENT, null);35                                 36                                 由LifecycleSupport 来广播给所有的接收者，37                                  接收者根据需要来判断是否需要处理【此处用到观察者模式 】38  39                                          40                         41                              而public class ContextConfig implements LifecycleListener42                              是所谓的接收者43                              其重写的 lifecycleEvent(LifecycleEvent event)方法中44                              45                               if (event.getType().equals(Lifecycle.CONFIGURE_START_EVENT)) {46                                         47                                configureStart();该方法是进行加载的具体方法  48      49     50             protected synchronized void configureStart()51                  -----------------》webconfig()52                                                         ：：：：：53       54                webconfig()中55                            {56                                                     String resource =57                                                             "/WEB-INF/classes/" + binding.getName();58                                                     try {59                                                         URL url = sContext.getResource(resource);60                                                         processAnnotationsUrl(url, webXml,61                                                                 webXml.isMetadataComplete());62                                                     } catch (MalformedURLException e) {63                                                         log.error(sm.getString(64                                                                 "contextConfig.webinfClassesUrl",65                                                                 resource), e);66                                                     }67                               68                            }69    70    ---------------》71     void java.org.apache.catalina.startup.ContextConfig.processAnnotationsUrl(URL url, WebXml fragment, boolean handlesTypesOnly)72                 ----------》73                  void java.org.apache.catalina.startup.ContextConfig.processAnnotationsJndi(URL url, WebXml fragment, boolean handlesTypesOnly)74                         ------------》75                              void java.org.apache.catalina.startup.ContextConfig.processAnnotationsStream(InputStream is, WebXml fragment, boolean handlesTypesOnly) throws ClassFormatException, IOException76                                     --------------》77                                          void java.org.apache.catalina.startup.ContextConfig.processAnnotationWebServlet(String className, AnnotationEntry ae, WebXml fragment)78 79                                                  ---------》80                                                   fragment.addServlet(servletDef);81                                                   fragment.addServletMapping(urlPattern, servletName);82  83  84     ------->webXml.configureContext(context);85  86                  public void configureContext(Context context) {87                       Wrapper wrapper = context.createWrapper();88                       context.addChild(wrapper);89                       context.addServletMapping(entry.getKey(), entry.getValue());90     91   >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>tomcat load web.xml>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>92   93