【死磕 Spring】----- ApplicationContext 相关接口架构分析

public interface WebApplicationContext extends ApplicationContext {
    ServletContext getServletContext();
}

public interface ConfigurableApplicationContext extends ApplicationContext, Lifecycle, Closeable { // 为 ApplicationContext 设置唯一 ID void setId(String id);
 // 为 ApplicationContext 设置 parent // 父类不应该被修改：如果创建的对象不可用时，则应该在构造函数外部设置它 void setParent(@Nullable ApplicationContext parent);
 // 设置 Environment void setEnvironment(ConfigurableEnvironment environment);
 // 获取 Environment @Override ConfigurableEnvironment getEnvironment();
 // 添加 BeanFactoryPostProcessor void addBeanFactoryPostProcessor(BeanFactoryPostProcessor postProcessor);
 // 添加 ApplicationListener void addApplicationListener(ApplicationListener<?> listener);
 // 添加 ProtocolResolver void addProtocolResolver(ProtocolResolver resolver);
 // 加载或者刷新配置 // 这是一个非常重要的方法 void refresh() throws BeansException, IllegalStateException;
 // 注册 shutdown hook void registerShutdownHook();
 // 关闭 ApplicationContext @Override void close();
 // ApplicationContext 是否处于激活状态 boolean isActive();
 // 获取当前上下文的 BeanFactory ConfigurableListableBeanFactory getBeanFactory() throws IllegalStateException;}

public interface ConfigurableWebApplicationContext extends WebApplicationContext, ConfigurableApplicationContext { void setServletContext(@Nullable ServletContext servletContext);
 void setServletConfig(@Nullable ServletConfig servletConfig);
 ServletConfig getServletConfig();
 void setNamespace(@Nullable String namespace);
 String getNamespace();
 void setConfigLocation(String configLocation);
 void setConfigLocations(String... configLocations);
 String[] getConfigLocations();}

ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
StudentService studentService = (StudentService)ac.getBean("studentService");

org.springframework.context.support.AbstractApplicationContext      
org.springframework.context.support.AbstractRefreshableApplicationContext            
org.springframework.context.support.AbstractRefreshableConfigApplicationContext                  
org.springframework.context.support.AbstractXmlApplicationContext                        
org.springframework.context.support.ClassPathXmlApplicationContext

BeanFactory：Spring 容器 Bean 的管理
MessageSource：管理 message ，实现国际化等功能
ApplicationEventPublisher：事件发布
ResourcePatternResolver：资源加载
EnvironmentCapable：系统 Environment（profile + Properties） 相关
Lifecycle：管理生命周期
Closeable：关闭，释放资源
InitializingBean：自定义初始化
BeanNameAware：设置 beanName 的 Aware 接口

 private MessageSource messageSource;
 // 实现 getMessage() 
 public String getMessage(String code, @Nullable Object[] args, @Nullable String defaultMessage, Locale locale) {
     // 委托给 messageSource 实现  
     return getMessageSource().getMessage(code, args, defaultMessage, locale); 
 }
 private MessageSource getMessageSource() throws IllegalStateException {
   if (this.messageSource == null) {
      throw new IllegalStateException("MessageSource not initialized - " +     "call 'refresh' before accessing messages via the context: " + this);  
   }  
   return this.messageSource; 
}

 public final String getMessage(String code, @Nullable Object[] args, @Nullable String defaultMessage, Locale locale) {
   String msg = getMessageInternal(code, args, locale);  
   if (msg != null) { 
     return msg;  
   }  
   if (defaultMessage == null) { 
     return getDefaultMessage(code);  
   }  
   return renderDefaultMessage(defaultMessage, args, locale); 
}

 @Override public void publishEvent(Object event) {
   publishEvent(event, null); 
 }
 protected void publishEvent(Object event, @Nullable ResolvableType eventType) {
   Assert.notNull(event, "Event must not be null");  
   if (logger.isTraceEnabled()) { 
     logger.trace("Publishing event in " + getDisplayName() + ": " + event);  
   }
   ApplicationEvent applicationEvent;  
   if (event instanceof ApplicationEvent) { 
     applicationEvent = (ApplicationEvent) event;  
   }  
   else { 
     applicationEvent = new PayloadApplicationEvent<>(this, event);   
     if (eventType == null) {  
       eventType = ((PayloadApplicationEvent) applicationEvent).getResolvableType();   
     }  
   }
   if (this.earlyApplicationEvents != null) { 
     this.earlyApplicationEvents.add(applicationEvent);  
   }  
   else { 
     getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType);  
   }
   if (this.parent != null) { 
     if (this.parent instanceof AbstractApplicationContext) {  
       ((AbstractApplicationContext) this.parent).publishEvent(event, eventType);   
     }   
     else {  
       this.parent.publishEvent(event);   
     }  
   } 
 }

 public Resource[] getResources(String locationPattern) throws IOException {
   return this.resourcePatternResolver.getResources(locationPattern); 
 }

 public ConfigurableEnvironment getEnvironment() {
   if (this.environment == null) { 
     this.environment = createEnvironment();  
   }  
   return this.environment; 
 }

 protected ConfigurableEnvironment createEnvironment() {
   return new StandardEnvironment(); 
 }

 @Override public void start() {
   getLifecycleProcessor().start();  
   publishEvent(new ContextStartedEvent(this)); 
 }
 @Override public void stop() {
   getLifecycleProcessor().stop(); 
   publishEvent(new ContextStoppedEvent(this));
 }
 @Override public boolean isRunning() {
   return (this.lifecycleProcessor != null && this.lifecycleProcessor.isRunning()); 
 }

 public void close() {
   synchronized (this.startupShutdownMonitor) { 
     doClose();   
     // If we registered a JVM shutdown hook, we don't need it anymore now:   
     // We've already explicitly closed the context.   
     if (this.shutdownHook != null) {  
       try {   
         Runtime.getRuntime().removeShutdownHook(this.shutdownHook);    
       }    
       catch (IllegalStateException ex) {   
         // ignore - VM is already shutting down    
       }   
     }  
   } 
 }   

 protected void doClose() {   
   // 省略部分代码   
   try {  
     // Publish shutdown event.    
     publishEvent(new ContextClosedEvent(this));   
   }   
   catch (Throwable ex) {  
     logger.warn("Exception thrown from ApplicationListener handling ContextClosedEvent", ex);   
   }
         
   // 省略部分代码   
   destroyBeans();   
   closeBeanFactory();   
   onClose();
   this.active.set(false);  
 } 

 public void afterPropertiesSet() {
   if (!isActive()) { 
     refresh();  
   } 
 }

 public void setBeanName(String name) {
   if (!this.setIdCalled) { 
     super.setId(name);   
     setDisplayName("ApplicationContext '" + name + "'");  
   } 
 }