AOP详解之一基本概念

/**
 * @author tcy
 * @time 2021-06-22 16:43
 */
@Aspect
@Component
public class OperationAspect {

  private static String CHECK_FLAG = "CHECK_FLAG:";

  /**
   * 定义切入点，切入点为com.ruoyi.project.medicinemanager.operate.controller下的所有函数
   */
  @Pointcut("execution(public * com.ruoyi.project.medicinemanager.operate.controller.OperateController.insert(..))||" +
    "execution(public * com.ruoyi.project.medicinemanager.operate.controller.OperateController.save(..))" +
    "||execution(public * com.ruoyi.project.medicinemanager.operate.controller.OperateController.approve(..))")
  public void OperationController() {
  }

  /**
   * 前置通知：在操作单之前执行的通知
   *
   * @param joinPoint
   * @throws Throwable
   */
  @Before("OperationController()")
  public void doBefore(JoinPoint joinPoint) throws Throwable {
    // 判断标志位状态
    String objectId = SecurityUtilsWrapper.getDeptIdStr();
    if (RedisUtil.get(CHECK_FLAG + objectId) != null) {
      if (RedisUtil.get(CHECK_FLAG + objectId).equals(1)) {
        throw new CustomException("盘点中不允许操作");
      }
    }
  }

}

@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			//1、刷新前的准备
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.
			//2、将会初始化 BeanFactory、加载 Bean、注册 Bean
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

			// Prepare the bean factory for use in this context.
			//3、设置 BeanFactory 的类加载器，添加几个 BeanPostProcessor，手动注册几个特殊的 bean
			prepareBeanFactory(beanFactory);

			try {
				//4、模板方法
				// Allows post-processing of the bean factory in context subclasses.
				postProcessBeanFactory(beanFactory);

				// Invoke factory processors registered as beans in the context.
				//执行BeanFactory后置处理器
				invokeBeanFactoryPostProcessors(beanFactory);

				// 5、Register bean processors that intercept bean creation.
				//注册bean后置处理器
				registerBeanPostProcessors(beanFactory);

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

				// Initialize event multicaster for this context.
				//初始化事件广播器
				initApplicationEventMulticaster();

				// Initialize other special beans in specific context subclasses.
				//6、模板方法--springboot实现了这个方法
				onRefresh();

				// Check for listener beans and register them.
				//7、注册监听器
				registerListeners();

				// Instantiate all remaining (non-lazy-init) singletons.
				//8、完成bean工厂的初始化**方法重要**********************************************
				finishBeanFactoryInitialization(beanFactory);

				//9、 Last step: publish corresponding event.
				//完成上下文的刷新工作
				finishRefresh();
			}

@Override
	protected Object createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
			throws BeanCreationException {

		if (logger.isTraceEnabled()) {
			logger.trace("Creating instance of bean '" + beanName + "'");
		}
		RootBeanDefinition mbdToUse = mbd;

		// Make sure bean class is actually resolved at this point, and
		// clone the bean definition in case of a dynamically resolved Class
		// which cannot be stored in the shared merged bean definition.
		// 确保 BeanDefinition 中的 Class 被加载
		Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
		if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
			mbdToUse = new RootBeanDefinition(mbd);
			mbdToUse.setBeanClass(resolvedClass);
		}

		// Prepare method overrides.
		// 准备方法覆写，这里又涉及到一个概念：MethodOverrides，它来自于 bean 定义中的 <lookup-method />
		// 和 <replaced-method />，如果读者感兴趣，回到 bean 解析的地方看看对这两个标签的解析。
		try {
			mbdToUse.prepareMethodOverrides();
		}
		catch (BeanDefinitionValidationException ex) {
			throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
					beanName, "Validation of method overrides failed", ex);
		}

		try {
			// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
			// 让 InstantiationAwareBeanPostProcessor 在这一步有机会返回代理，
			// 在 《Spring AOP 源码分析》那篇文章中有解释，这里先跳过 aop入口*******************************************************
			// AOP核心方法，用来处理使用@Aspect注解标识的切面bean，读取切面bean中的信息，添加到advisorsCache缓存中，以便后面生成动态代理
			Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
			if (bean != null) {
				return bean;
			}
		}
		catch (Throwable ex) {
			throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,
					"BeanPostProcessor before instantiation of bean failed", ex);
		}

		try {
			// 重头戏，创建实例化 bean
			Object beanInstance = doCreateBean(beanName, mbdToUse, args);
			if (logger.isTraceEnabled()) {
				logger.trace("Finished creating instance of bean '" + beanName + "'");
			}
			return beanInstance;
		}
		catch (BeanCreationException | ImplicitlyAppearedSingletonException ex) {
			// A previously detected exception with proper bean creation context already,
			// or illegal singleton state to be communicated up to DefaultSingletonBeanRegistry.
			throw ex;
		}
		catch (Throwable ex) {
			throw new BeanCreationException(
					mbdToUse.getResourceDescription(), beanName, "Unexpected exception during bean creation", ex);
		}
	}