spring ioc實現原理

spring ioc實現原理

一、一個普通的調用

ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); GsonFormatBean bean = (GsonFormatBean) context.getBean("GsonFormatBean"); bean.isPalindrome(100);

 

1.1 分析第一步

 

 

 

 建立一個classPathXmlApplication的context，主要的實如今abstractAppplicationContext的refresh()這個方法中

@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

			// Prepare the bean factory for use in this context.
			prepareBeanFactory(beanFactory);

			try {
				// Allows post-processing of the bean factory in context subclasses.
				postProcessBeanFactory(beanFactory);

				// Invoke factory processors registered as beans in the context.
				invokeBeanFactoryPostProcessors(beanFactory);

				// Register bean processors that intercept bean creation.
				registerBeanPostProcessors(beanFactory);

				// Initialize message source for this context.
				initMessageSource();

				// Initialize event multicaster for this context.
				initApplicationEventMulticaster();

				// Initialize other special beans in specific context subclasses.
				onRefresh();

				// Check for listener beans and register them.
				registerListeners();

				// Instantiate all remaining (non-lazy-init) singletons.
				finishBeanFactoryInitialization(beanFactory);

				// Last step: publish corresponding event.
				finishRefresh();
			}

			catch (BeansException ex) {
				if (logger.isWarnEnabled()) {
					logger.warn("Exception encountered during context initialization - " +
							"cancelling refresh attempt: " + ex);
				}

				// Destroy already created singletons to avoid dangling resources.
				destroyBeans();

				// Reset 'active' flag.
				cancelRefresh(ex);

				// Propagate exception to caller.
				throw ex;
			}

			finally {
				// Reset common introspection caches in Spring's core, since we
				// might not ever need metadata for singleton beans anymore...
				resetCommonCaches();
			}
		}
	}

 

使用對象鎖保證只有一個線程訪問邏輯

 第一步：

 

設置容器的一些全局性參數，好比closed，active等參數

 

第二步：

 

 

告訴父類建立一個bean工廠

 

 刷新整個bean工廠，獲取一個ConfigurableListableBeanFacotory，返回bean工廠。

 

刷新beanFactory

 

 

 建立一個DefaultListableBeanFactory，設置一些屬性，加載beanDefinition，具體的實如今abstractxmlApplicationContext、AnnotationWebConfigApplicationContext等

 

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

容器怎麼實現加載全部的bean

 

 兩個關鍵的方法：

 

 容器註冊全部的beanDefinitions

 

 

解析單個bean的操做 

 

 

 最終生成beanDefination，也就是將xml映射成爲一個bean

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------