Spring源码阅读（七）

这一讲主要分析bean注册过程中各种初始化方法回调的执行逻辑（initializeBean）

    /**
     * Initialize the given bean instance, applying factory callbacks
     * as well as init methods and bean post processors.
     * 生成bean实例，并且回调诸如init methods，bean post processors方法
     * <p>Called from {@link #createBean} for traditionally defined beans,
     * and from {@link #initializeBean} for existing bean instances.
     * @param beanName the bean name in the factory (for debugging purposes)
     * @param bean the new bean instance we may need to initialize
     * @param mbd the bean definition that the bean was created with
     * (can also be {@code null}, if given an existing bean instance)
     * @return the initialized bean instance (potentially wrapped)
     * @see BeanNameAware
     * @see BeanClassLoaderAware
     * @see BeanFactoryAware
     * @see #applyBeanPostProcessorsBeforeInitialization
     * @see #invokeInitMethods
     * @see #applyBeanPostProcessorsAfterInitialization
     */
    protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {
        if (System.getSecurityManager() != null) {
            AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
                invokeAwareMethods(beanName, bean);
                return null;
            }, getAccessControlContext());
        }
        else {
            // 执行BeanNameAware，BeanClassLoaderAware，BeanFactoryAware接口方法
            invokeAwareMethods(beanName, bean);
        }

        Object wrappedBean = bean;
        if (mbd == null || !mbd.isSynthetic()) {
            // 执行BeanPostProcessor的postProcessBeforeInitialization方法，包括@PostConstruct注解方法
            wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
        }

        try {
            // 执行InitializingBean的afterPropertiesSet方法，包括init-method方法
            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()) {
            // 执行BeanPostProcessor的postProcessAfterInitialization方法
            wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
        }

        return wrappedBean;
    }