Spring注解系列十五：生命周期-BeanPostProcessor原理

喜欢ヅ旅行 2022-02-03 00:29 276阅读 0赞

1、AbstractAutowireCapableBeanFactory

//在bean初始化之前给bean进行属性赋值
    protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
       PropertyValues pvs = mbd.getPropertyValues();
         if (bw == null) {
             if (!((PropertyValues)pvs).isEmpty()) {
                 throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
             }
         } else {
             boolean continueWithPropertyPopulation = true;
             if (!mbd.isSynthetic() && this.hasInstantiationAwareBeanPostProcessors()) {
                 Iterator var6 = this.getBeanPostProcessors().iterator();
    
                 while(var6.hasNext()) {
                     BeanPostProcessor bp = (BeanPostProcessor)var6.next();
                     if (bp instanceof InstantiationAwareBeanPostProcessor) {
                         InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor)bp;
                         if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
                             continueWithPropertyPopulation = false;
                             break;
                         }
                     }
                 }
             }
    
             if (continueWithPropertyPopulation) {
                 if (mbd.getResolvedAutowireMode() == 1 || mbd.getResolvedAutowireMode() == 2) {
                     MutablePropertyValues newPvs = new MutablePropertyValues((PropertyValues)pvs);
                     if (mbd.getResolvedAutowireMode() == 1) {
                         this.autowireByName(beanName, mbd, bw, newPvs);
                     }
    
                     if (mbd.getResolvedAutowireMode() == 2) {
                         this.autowireByType(beanName, mbd, bw, newPvs);
                     }
    
                     pvs = newPvs;
                 }
    
                 boolean hasInstAwareBpps = this.hasInstantiationAwareBeanPostProcessors();
                 boolean needsDepCheck = mbd.getDependencyCheck() != 0;
                 if (hasInstAwareBpps || needsDepCheck) {
                     PropertyDescriptor[] filteredPds = this.filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
                     if (hasInstAwareBpps) {
                         Iterator var9 = this.getBeanPostProcessors().iterator();
    
                         while(var9.hasNext()) {
                             BeanPostProcessor bp = (BeanPostProcessor)var9.next();
                             if (bp instanceof InstantiationAwareBeanPostProcessor) {
                                 InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor)bp;
                                 pvs = ibp.postProcessPropertyValues((PropertyValues)pvs, filteredPds, bw.getWrappedInstance(), beanName);
                                 if (pvs == null) {
                                     return;
                                 }
                             }
                         }
                     }
    
                     if (needsDepCheck) {
                         this.checkDependencies(beanName, mbd, filteredPds, (PropertyValues)pvs);
                     }
                 }
    
                 this.applyPropertyValues(beanName, mbd, bw, (PropertyValues)pvs);
             }
         }
     }
    
    //初始化bean
     protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
       if (System.getSecurityManager() != null) {
            AccessController.doPrivileged(new PrivilegedAction<Object>() {
                public Object run() {
                    AbstractAutowireCapableBeanFactory.this.invokeAwareMethods(beanName, bean);
                    return null;
                }
            }, this.getAccessControlContext());
        } else {
            this.invokeAwareMethods(beanName, bean);
        }
    
        Object wrappedBean = bean;
        if (mbd == null || !mbd.isSynthetic()) {
        	//在初始化之前工作
            wrappedBean = this.applyBeanPostProcessorsBeforeInitialization(bean, beanName);
        }
    
        try {
        	//执行自定义初始化
            this.invokeInitMethods(beanName, wrappedBean, mbd);
        } catch (Throwable var6) {
            throw new BeanCreationException(mbd != null ? mbd.getResourceDescription() : null, beanName, "Invocation of init method failed", var6);
        }
    
        if (mbd == null || !mbd.isSynthetic()) {
        	//在初始化之后工作
            wrappedBean = this.applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
        }
    
        return wrappedBean;
    }
    
    
    //执行初始化
    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 (this.logger.isDebugEnabled()) {
                this.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;
                        }
                    }, this.getAccessControlContext());
                } catch (PrivilegedActionException var6) {
                    throw var6.getException();
                }
            } else {
                ((InitializingBean)bean).afterPropertiesSet();
            }
        }
    
        if (mbd != null) {
            String initMethodName = mbd.getInitMethodName();
            if (initMethodName != null && (!isInitializingBean || !"afterPropertiesSet".equals(initMethodName)) && !mbd.isExternallyManagedInitMethod(initMethodName)) {
                this.invokeCustomInitMethod(beanName, bean, mbd);
            }
        }
    
    }
    
    
    //初始化之前
    public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName) throws BeansException {
       Object result = existingBean;
        Iterator var4 = this.getBeanPostProcessors().iterator();
    
    
    	//遍历得到容器中所有的BeanPostProcessor
        do {
            if (!var4.hasNext()) {
                return result;
            }
    
            BeanPostProcessor beanProcessor = (BeanPostProcessor)var4.next();
            //执行postProcessorsBeforeInitialization方法，一但返回null，跳出for循环。
            result = beanProcessor.postProcessBeforeInitialization(result, beanName);
        } while(result != null);
    
        return result;
    }
    
    
    //初始化之后
    public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {
       Object result = existingBean;
        Iterator var4 = this.getBeanPostProcessors().iterator();
    
        do {
            if (!var4.hasNext()) {
                return result;
            }
    
            BeanPostProcessor beanProcessor = (BeanPostProcessor)var4.next();
            result = beanProcessor.postProcessAfterInitialization(result, beanName);
        } while(result != null);
    
        return result;
    }