Spring註解之BeanPostProcessor與InitializingBean
阿新 • • 發佈:2018-05-18
cati 構造 ID The invoke leg .net 源碼 bool
/**
* BeanPostProcessor 為每個bean實例化時提供個性化的修改,做些包裝等
*/ package org.springframework.beans.factory.config; import org.springframework.beans.BeansException; public interface BeanPostProcessor { /** * 在bean實例化前調用*/ Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;/** * 在bean實例化後調用,如果bean實現了InitializingBean,則在執行完* 該接口的afterPropertiesSet方法後調用 ,如果實現了init-method則 * 在執行完init-method後調用*/ Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException; }
package org.springframework.beans.factory; /** /* *InitializingBean 為實現該接口的bean提供默認的初始化方法 *也可以在xml配置bean的使用init-method來實現初始化方法 */*/ public interface InitializingBean { void afterPropertiesSet() throws Exception; }
InitializingBean和BeanPostProcessor的執行順序:構造方法-->BeanPostProcessor-->InitializingBean-->bean中的初始化方法
bean的最終初始化是由AbstractAutowireCapableBeanFactory的initializeBean方法來完成的,下面是該方法的源碼
protected Object initializeBean(finalString beanName, final Object bean, RootBeanDefinition mbd) { if (System.getSecurityManager() != null) { AccessController.doPrivileged(new PrivilegedAction<Object>() { public Object run() { **invokeAwareMethods**(beanName, bean); return null; } }, getAccessControlContext()); } else { invokeAwareMethods(beanName, bean); } Object wrappedBean = bean; if (mbd == null || !mbd.isSynthetic()) { wrappedBean = **applyBeanPostProcessorsBeforeInitialization**(wrappedBean, beanName); } try { **invokeInitMethods**(beanName, wrappedBean, mbd); } catch (Throwable ex) { throw new BeanCreationException( (mbd != null ? mbd.getResourceDescription() : null), beanName, "Invocation of init method failed", ex); } if (mbd == null || !mbd.isSynthetic()) { wrappedBean = **applyBeanPostProcessorsAfterInitialization**(wrappedBean, beanName); } return wrappedBean; }
可以看到initializeBean主要有四步驟
1. invokeAwareMethods 調用實現Aware接口方法,這裏只針對三種Aware接口BeanNameAware,BeanClassLoaderAware,BeanFactoryAware,方法如下
private void invokeAwareMethods(final String beanName, final Object bean) { if (bean instanceof Aware) { if (bean instanceof BeanNameAware) { ((BeanNameAware) bean).setBeanName(beanName); } if (bean instanceof BeanClassLoaderAware) { ((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader()); } if (bean instanceof BeanFactoryAware) { ((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this); } } }
- applyBeanPostProcessorsBeforeInitialization 調用所有實現BeanPostProcessor類 的 postProcessBeforeInitialization方法,源碼如下
public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName) throws BeansException { Object result = existingBean; for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) { result = beanProcessor.postProcessBeforeInitialization(result, beanName); if (result == null) { return result; } } return result; }
- invokeInitMethods 調用bean的初始化方法,如果bean實現了InitializingBean 接口,則調用afterPropertiesSet方法,如果有配置init-method,則調用配置的初始化方法,源碼如下:
protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd) throws Throwable { boolean isInitializingBean = (bean instanceof InitializingBean); if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) { if (logger.isDebugEnabled()) { logger.debug("Invoking afterPropertiesSet() on bean with name ‘" + beanName + "‘"); } if (System.getSecurityManager() != null) { try { AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() { public Object run() throws Exception { ((InitializingBean) bean).afterPropertiesSet(); return null; } }, getAccessControlContext()); } catch (PrivilegedActionException pae) { throw pae.getException(); } } else { ((InitializingBean) bean).**afterPropertiesSet**(); } } if (mbd != null) { String initMethodName = mbd.getInitMethodName(); if (initMethodName != null && !(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) && !mbd.isExternallyManagedInitMethod(initMethodName)) { **invokeCustomInitMethod**(beanName, bean, mbd); } } }
- applyBeanPostProcessorsAfterInitialization 調用所有實現BeanPostProcessor類 的 postProcessAfterInitialization方法,源碼如下
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException { Object result = existingBean; for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) { result = beanProcessor.postProcessAfterInitialization(result, beanName); if (result == null) { return result; } } return result; }
註:https://blog.csdn.net/zhaiyang1992/article/details/52200602
Spring註解之BeanPostProcessor與InitializingBean