public class SpringUtils implements ApplicationListener<ApplicationEvent> {
	private static ApplicationContext applicationContext;
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
	public void onApplicationEvent(ApplicationEvent event) {
        if (event instanceof ContextRefreshedEvent) {
            ContextRefreshedEvent e = (ContextRefreshedEvent)event;
            if (e.getApplicationContext().getParent() == null) {
                applicationContext = e.getApplicationContext();
            }
        }
    }
	public static <T> T getBean(Class<T> clazz){
		return getApplicationContext().getBean(clazz);
	}
}

@Service
public class TestService{
}

@Component
public class TestInit{
    @PostConstruct
    public void init(){
        SpringUtils.getBean(TestService.class);
    }
}

@Component
public class SpringUtils implements BeanFactoryPostProcessor, ApplicationContextAware {
    private static ConfigurableListableBeanFactory beanFactory;
    private static ApplicationContext applicationContext;
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        SpringUtils.beanFactory = beanFactory;
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        SpringUtils.applicationContext = applicationContext;
    }
    /**
     * 獲取{@link ApplicationContext}
     *
     * @return {@link ApplicationContext}
     */
    public ApplicationContext getApplicationContext() {
        return applicationContext;
    }
    public ListableBeanFactory getBeanFactory() {
        return null == beanFactory ? applicationContext : beanFactory;
    }
    public ConfigurableListableBeanFactory getConfigurableBeanFactory() throws UtilException {
        final ConfigurableListableBeanFactory factory;
        if (null != beanFactory) {
            factory = beanFactory;
        } else if (applicationContext instanceof ConfigurableApplicationContext) {
            factory = ((ConfigurableApplicationContext) applicationContext).getBeanFactory();
        } else {
            throw new UtilException("No ConfigurableListableBeanFactory from context!");
        }
        return factory;
    }
    @SuppressWarnings("unchecked")
    public <T> T getBean(String name) {
        return (T) getBeanFactory().getBean(name);
    }
    /**
     * 通過class獲取Bean
     *
     * @param <T>   Bean類型
     * @param clazz Bean類
     * @return Bean對象
     */
    public <T> T getBean(Class<T> clazz) {
        return getBeanFactory().getBean(clazz);
    }
    /**
     * 通過name,以及Clazz返回指定的Bean
     *
     * @param <T>   bean類型
     * @param name  Bean名稱
     * @param clazz bean類型
     * @return Bean對象
     */
    public <T> T getBean(String name, Class<T> clazz) {
        return getBeanFactory().getBean(name, clazz);
    }
    /**
     * 從spring容器中獲取相關(guān)降級的bean
     *
     * @param fallbackClass 降級的Class類對象
     * @param paramValues   參數(shù)值
     * @return 相關(guān)降級的bean
     */
    public Object getBean(Class<?> fallbackClass, Object[] paramValues) {
        return getBeanFactory().getBean(fallbackClass, paramValues);
    }
    /**
     * 通過類型參考返回帶泛型參數(shù)的Bean
     *
     * @param reference 類型參考，用于持有轉(zhuǎn)換后的泛型類型
     * @param <T>       Bean類型
     * @return 帶泛型參數(shù)的Bean
     * @since 5.4.0
     */
    @SuppressWarnings("unchecked")
    public <T> T getBean(TypeReference<T> reference) {
        final ParameterizedType parameterizedType = (ParameterizedType) reference.getType();
        final Class<T> rawType = (Class<T>) parameterizedType.getRawType();
        final Class<?>[] genericTypes = Arrays.stream(parameterizedType.getActualTypeArguments()).map(type -> (Class<?>) type).toArray(Class[]::new);
        final String[] beanNames = getBeanFactory().getBeanNamesForType(ResolvableType.forClassWithGenerics(rawType, genericTypes));
        return getBean(beanNames[0], rawType);
    }
    /**
     * 獲取指定類型對應(yīng)的所有Bean，包括子類
     *
     * @param <T>  Bean類型
     * @param type 類、接口，null表示獲取所有bean
     * @return 類型對應(yīng)的bean，key是bean注冊的name，value是Bean
     * @since 5.3.3
     */
    public <T> Map<String, T> getBeansOfType(Class<T> type) {
        return getBeanFactory().getBeansOfType(type);
    }
    /**
     * 獲取指定類型對應(yīng)的Bean名稱，包括子類
     *
     * @param type 類、接口，null表示獲取所有bean名稱
     * @return bean名稱
     * @since 5.3.3
     */
    public String[] getBeanNamesForType(Class<?> type) {
        return getBeanFactory().getBeanNamesForType(type);
    }
    /**
     * 獲取配置文件配置項的值
     *
     * @param key 配置項key
     * @return 屬性值
     * @since 5.3.3
     */
    public String getProperty(String key) {
        if (null == applicationContext) {
            return null;
        }
        return applicationContext.getEnvironment().getProperty(key);
    }
    /**
     * 獲取應(yīng)用程序名稱
     *
     * @return 應(yīng)用程序名稱
     * @since 5.7.12
     */
    public String getApplicationName() {
        return getProperty("spring.application.name");
    }
    /**
     * 獲取當前的環(huán)境配置，無配置返回null
     *
     * @return 當前的環(huán)境配置
     * @since 5.3.3
     */
    public static String[] getActiveProfiles() {
        if (null == applicationContext) {
            return null;
        }
        return applicationContext.getEnvironment().getActiveProfiles();
    }
    /**
     * 獲取當前的環(huán)境配置，當有多個環(huán)境配置時，只獲取第一個
     *
     * @return 當前的環(huán)境配置
     * @since 5.3.3
     */
    public String getActiveProfile() {
        final String[] activeProfiles = getActiveProfiles();
        return ArrayUtil.isNotEmpty(activeProfiles) ? activeProfiles[0] : null;
    }
    /**
     * 動態(tài)向Spring注冊Bean
     * <p>
     * 由{@link org.springframework.beans.factory.BeanFactory} 實現(xiàn)，通過工具開放API
     * <p>
     * 更新: shadow 2021-07-29 17:20:44 增加自動注入，修復注冊bean無法反向注入的問題
     *
     * @param <T>      Bean類型
     * @param beanName 名稱
     * @param bean     bean
     * @author shadow
     * @since 5.4.2
     */
    public <T> void registerBean(String beanName, T bean) {
        final ConfigurableListableBeanFactory factory = getConfigurableBeanFactory();
        factory.autowireBean(bean);
        factory.registerSingleton(beanName, bean);
    }
    /**
     * 注銷bean
     * <p>
     * 將Spring中的bean注銷，請謹慎使用
     *
     * @param beanName bean名稱
     * @author shadow
     * @since 5.7.7
     */
    public void unregisterBean(String beanName) {
        final ConfigurableListableBeanFactory factory = getConfigurableBeanFactory();
        if (factory instanceof DefaultSingletonBeanRegistry) {
            DefaultSingletonBeanRegistry registry = (DefaultSingletonBeanRegistry) factory;
            registry.destroySingleton(beanName);
        } else {
            throw new UtilException("Can not unregister bean, the factory is not a DefaultSingletonBeanRegistry!");
        }
    }
    /**
     * 發(fā)布事件
     *
     * @param event the event to publish
     * @since 5.7.12
     */
    public void publishEvent(ApplicationEvent event) {
        if (null != applicationContext) {
            applicationContext.publishEvent(event);
        }
    }
}

@FunctionalInterface
public interface BeanFactoryPostProcessor {
    void postProcessBeanFactory(ConfigurableListableBeanFactory var1) throws BeansException;
}

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
        //主要是這一行
		PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
		// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
		// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
		if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
			beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
			beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
		}
	}
public static void invokeBeanFactoryPostProcessors(
			ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
		/**因代碼太長，省略了***/
		//這里從beanFacoty中通過BeanFactoryPostProcessor類型來獲取Bean名稱，就可以拿到我們自定義的BeanFactoryPostProcessor
		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
		List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		for (String ppName : postProcessorNames) {
			if (processedBeans.contains(ppName)) {
				// skip - already processed in first phase above
			}
			//這里是優(yōu)先級的處理，如果我們有多個自定義的BeanFactoryPostProcessor,可以通過優(yōu)先級來定義執(zhí)行順序
			else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
			}
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			}
			else {
				nonOrderedPostProcessorNames.add(ppName);
			}
		}
		// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
		//這里先處理實現(xiàn)了PriorityOrdered接口的BeanFactoryPostProcessor，也就是定義了優(yōu)先級的先處理
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		//再處理實現(xiàn)了Ordered接口的BeanFactoryPostProcessor
		List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
		for (String postProcessorName : orderedPostProcessorNames) {
			orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
		// Finally, invoke all other BeanFactoryPostProcessors.
		List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
		for (String postProcessorName : nonOrderedPostProcessorNames) {
			nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		//這里才到了處理普通的自定義BeanFactoryPostProcessors
		invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
		// Clear cached merged bean definitions since the post-processors might have
		// modified the original metadata, e.g. replacing placeholders in values...
		beanFactory.clearMetadataCache();
	}
private static void invokeBeanFactoryPostProcessors(
			Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {
		for (BeanFactoryPostProcessor postProcessor : postProcessors) {
			postProcessor.postProcessBeanFactory(beanFactory);
		}
	}