电子商务公司网站设计,wordpress标签归档,搜索网站的设计与建设,wordpress商城自动发货BeanFactoryPostProcessor和BeanPostProcessor这两个接口都是初始化bean时对外暴露的入口之一#xff0c;和Aware类似#xff08;PS:关于spring的hook可以看看Spring钩子方法和钩子接口的使用详解讲的蛮详细#xff09;本文也主要是学习具体的钩子的细节#xff0c;以便于实…BeanFactoryPostProcessor和BeanPostProcessor这两个接口都是初始化bean时对外暴露的入口之一和Aware类似PS:关于spring的hook可以看看Spring钩子方法和钩子接口的使用详解讲的蛮详细本文也主要是学习具体的钩子的细节以便于实际开发中我们能有效率例如如何在scala中如何获取springboot的启动类等等一些中间件为了监控整个系统的服务也需要获取到spring容器数据和状态。 接下来具体学习和了解下BeanFactoryPostProcessor和BeanPostProcessor。 BeanFactoryPostProcessor bean工厂的bean属性处理容器说通俗一些就是可以管理我们的bean工厂内所有的beandefinition未实例化数据可以随心所欲的修改属性。 使用方法 public class CustomBeanFactoryPostProcessor implements BeanFactoryPostProcessor {/*** 主要是用来自定义修改持有的bean* ConfigurableListableBeanFactory 其实就是DefaultListableBeanDefinition对象* param beanFactory* throws BeansException*/public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {System.out.println(调用了自定义的BeanFactoryPostProcessor beanFactory);Iterator it beanFactory.getBeanNamesIterator();String[] names beanFactory.getBeanDefinitionNames();// 获取了所有的bean名称列表for(int i0; inames.length; i){String name names[i];BeanDefinition bd beanFactory.getBeanDefinition(name);System.out.println(name bean properties: bd.getPropertyValues().toString());// 本内容只是个demo打印持有的bean的属性情况}} }context:property-placeholder locationpro.properties / bean idstudent classStudent init-methodinit / bean classCustomBeanFactoryPostProcessor idcustomBeanFactoryPostProcessor /输出结果 源码分析 毫无疑问肯定已经解析xml了继续看refresh函数 AbstractApplicationContext 文件 public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {// Prepare this context for refreshing.prepareRefresh();// 解析xml完成存储在一个具体的bean工厂中ConfigurableListableBeanFactory beanFactory obtainFreshBeanFactory();// bean工厂的初始化操作prepareBeanFactory(beanFactory);try {// 由子类继承去实现该类当前该方法为空postProcessBeanFactory(beanFactory);// invoke 其中存在的BeanFactoryPostProcessors,也就是我们现在说的invokeBeanFactoryPostProcessors(beanFactory);... PostProcessorRegistrationDelegate 文件 invokeBeanFactoryPostProcessors方法的参数为bean工厂ConfigurableListableBeanFactory和当前已知的postprocessor对象函数分为了好几部分去处理截取其中我们关心的部分即可其实还包含了优先级、属性等类似处理过程 String[] postProcessorNames beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);// 筛选出bean工程中存在的所有实现BeanFactoryPostProcessor类的类名称ListBeanFactoryPostProcessor priorityOrderedPostProcessors new ArrayListBeanFactoryPostProcessor();ListString orderedPostProcessorNames new ArrayListString();ListString nonOrderedPostProcessorNames new ArrayListString();for (String ppName : postProcessorNames) {if (processedBeans.contains(ppName)) {// 已经存在了不再处理}else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));// 为PriorityOrdered类型}else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {orderedPostProcessorNames.add(ppName);// 为Ordered类型}else {nonOrderedPostProcessorNames.add(ppName);// 这个就是我们当前需要关心的PostProcessors}}...ListBeanFactoryPostProcessor nonOrderedPostProcessors new ArrayListBeanFactoryPostProcessor();for (String postProcessorName : nonOrderedPostProcessorNames) {nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));// 获取自定义的BeanFactoryPostProcessor// 这里有一点需要注意到}invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);上述代码中nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));中使用了getBean起初没注意到以为是生成具体的对象然后修改其实不是getBean后面还有一个参数BeanFactoryPostProcessor.class注意看这个函数会发现返回的是一个抽象类结论就是nonOrderedPostProcessors添加的不是bean实例而是beandefinition在实例化前这点很重要 private static void invokeBeanFactoryPostProcessors(Collection? extends BeanFactoryPostProcessor postProcessors, ConfigurableListableBeanFactory beanFactory) {for (BeanFactoryPostProcessor postProcessor : postProcessors) {postProcessor.postProcessBeanFactory(beanFactory);// 调用每一个自定义的BeanFactoryPostProcessor的方法// 在本文章中就会去调用自定义的CustomBeanFactoryPostProcessor的postProcessBeanFactory方法} }再多说一点关于上面的getBeanNamesForType函数从名字肯定很容易理解了根据传递的类型获取容器中的beanName。了解下其内部的实现原理 DefaultListableBeanFactory 文件的 getBeanNamesForType函数 // type:类的类型名称 // includeNonSingletons:返回数据包含了非单例beanName // allowEagerInit: 可以提前加载初始化 public String[] getBeanNamesForType(Class? type, boolean includeNonSingletons, boolean allowEagerInit) {if (!isConfigurationFrozen() || type null || !allowEagerInit) {// 不可用缓存、类型无效、不允许提前加载初始化// 需要获取当前type的原始类型继续获取数据return doGetBeanNamesForType(ResolvableType.forRawClass(type), includeNonSingletons, allowEagerInit);}MapClass?, String[] cache (includeNonSingletons ? this.allBeanNamesByType : this.singletonBeanNamesByType);String[] resolvedBeanNames cache.get(type);// 如果缓存已经存储了该数据则无需再计算直接返回即可if (resolvedBeanNames ! null) {return resolvedBeanNames;}resolvedBeanNames doGetBeanNamesForType(ResolvableType.forRawClass(type), includeNonSingletons, true);// 这一步就是真正的获取数据遍历beanDefinitionNames的每一个数据符合要求的就会加入到返回的列表中if (ClassUtils.isCacheSafe(type, getBeanClassLoader())) {cache.put(type, resolvedBeanNames);// 便于下一次获取加入缓存中}return resolvedBeanNames; }BeanPostProcessor 从范围上来说从上面的所有的bean成为了特定的bean其次BeanFactoryPostProcessor可以在初始化前修改bean的属性等情况但是BeanPostProcessor只能在初始化后注意初始化不包括init方法执行一些操作。 网上很多文章都说BeanPostProcessor不能修改bean属性其实我看来未必当其实例化之后完全可以拿到实例化后的对象对对象进行一些改值操作也完全可以的 使用方法 public class Student {Value(${name})private String className;public Student() {System.out.println(constructor loading);}public void init(){System.out.println(init loading);} }public class CustomBeanPostProcessor implements BeanPostProcessor {public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {if(bean instanceof Student){// 如果当前的bean是Student,则打印日志System.out.println(postProcessBeforeInitialization bean : beanName);}return bean;}public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {if(bean instanceof Student){System.out.println(postProcessAfterInitialization bean : beanName);}return bean;} }bean idstudent classStudent init-methodinit / bean classCustomBeanPostProcessor idcustomBeanPostProcessor /输出结果 先打印出了构造器内部执行的话意味着这个时候实例化了Student类 在init方法前执行了postProcessBeforeInitialization 在init方法后执行了postProcessAfterInitialization 源码分析 入口依旧是refresh函数在完成初始化之后进入到finishBeanFactoryInitialization(beanFactory)执行BeanPostProcessor的相关操作中间的流程过长包含了getBean操作genBean操作过于繁琐后续再介绍。 AbstractAutowireCapableBeanFactory 文件 protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {if (System.getSecurityManager() ! null) {AccessController.doPrivileged(new PrivilegedActionObject() {Overridepublic Object run() {invokeAwareMethods(beanName, bean);return null;}}, getAccessControlContext());}else {invokeAwareMethods(beanName, bean);// aware同样是对外提供的钩子}Object wrappedBean bean;if (mbd null || !mbd.isSynthetic()) {wrappedBean applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);// 这一步就是执行自定义的beanpostprocessor的before操作}try {invokeInitMethods(beanName, wrappedBean, mbd);// 执行init方法}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);// 这一步就是执行自定义的beanpostprocessor的after操作}return wrappedBean; }public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)throws BeansException {Object result existingBean;for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {// 获取所有的BeanPostProcessor对象执行postProcessBeforeInitialization方法result beanProcessor.postProcessBeforeInitialization(result, beanName);if (result null) {return result;}}return result;// 然后把执行结果返回 }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; }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 PrivilegedExceptionActionObject() {Overridepublic Object run() throws Exception {((InitializingBean) bean).afterPropertiesSet();return null;}}, getAccessControlContext());}catch (PrivilegedActionException pae) {throw pae.getException();}}else {((InitializingBean) bean).afterPropertiesSet();}}if (mbd ! null) {// invoke 反射执行init方法String initMethodName mbd.getInitMethodName();if (initMethodName ! null !(isInitializingBean afterPropertiesSet.equals(initMethodName)) !mbd.isExternallyManagedInitMethod(initMethodName)) {invokeCustomInitMethod(beanName, bean, mbd);}} }