tomcat加载web.xml

 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 those
12              * components that use a separate component to perform configuration and
13              * need to signal when configuration should be performed - usually after
14              * {@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 LifecycleListener
42                              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, IOException
76                                     --------------》
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