源码分析

java">/**** @author Andy Wilkinson* @author Madhura Bhave* @author Tyler Van Gorder* @author Phillip Webb* @since 2.2.0* @see LazyInitializationExcludeFilter** 主要用于延迟初始化 Bean 的配置。它通过修改 BeanFactory 的配置来确保某些 Bean 在实际需要时才进行初始化，而不是在应用启动时就全部初始化。这有助于提高应用的启动速度和资源利用率。*/
public final class LazyInitializationBeanFactoryPostProcessor implements BeanFactoryPostProcessor, Ordered {/*** 在BeanFactory初始化后对bean进行后处理* 主要用于处理延迟初始化相关的逻辑** @param beanFactory ConfigurableListableBeanFactory类型的参数，代表BeanFactory* @throws BeansException 如果处理过程中遇到错误，则抛出此异常*/@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {// Take care not to force the eager init of factory beans when getting filters//获取LazyInitializationExcludeFilter类型的beanCollection<LazyInitializationExcludeFilter> filters = beanFactory.getBeansOfType(LazyInitializationExcludeFilter.class, false, false).values();//遍历容器中的所有bean定义for (String beanName : beanFactory.getBeanDefinitionNames()) {//根据beanName获取bean的定义BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanName);//检查bean定义是否为AbstractBeanDefinition类型if (beanDefinition instanceof AbstractBeanDefinition) {//如果是，则进行延迟初始化处理postProcess(beanFactory, filters, beanName, (AbstractBeanDefinition) beanDefinition);}}}/*** 根据条件更新bean的懒初始化状态** @param beanFactory Bean工厂，用于获取bean的相关信息* @param filters 排除懒初始化的过滤器集合* @param beanName 当前bean的名称* @param beanDefinition 当前bean的定义，包含懒初始化状态*/private void postProcess(ConfigurableListableBeanFactory beanFactory,Collection<LazyInitializationExcludeFilter> filters, String beanName,AbstractBeanDefinition beanDefinition) {// 如果bean的懒初始化状态已明确，无需处理Boolean lazyInit = beanDefinition.getLazyInit();if (lazyInit != null) {return;}// 获取bean的类型Class<?> beanType = getBeanType(beanFactory, beanName);//如果该bean不再filters列表中，则LazyInit设置为trueif (!isExcluded(filters, beanName, beanDefinition, beanType)) {//给这个bean设置延迟初始化beanDefinition.setLazyInit(true);}}private Class<?> getBeanType(ConfigurableListableBeanFactory beanFactory, String beanName) {try {return beanFactory.getType(beanName, false);}catch (NoSuchBeanDefinitionException ex) {return null;}}/*** 判断指定的bean是否被排除在懒初始化之外** @param filters 一个包含多个排除过滤器的集合，用于判断bean是否应该被排除* @param beanName bean的名称，用于在过滤时进行标识* @param beanDefinition bean的定义信息，包含了bean的元数据* @param beanType bean的类型，可能为null，用于类型级别的过滤* @return 如果bean被至少一个过滤器认定为需要排除，则返回true；否则返回false*/private boolean isExcluded(Collection<LazyInitializationExcludeFilter> filters, String beanName,AbstractBeanDefinition beanDefinition, Class<?> beanType) {// 如果bean类型不为null，遍历所有过滤器以判断bean是否应被排除if (beanType != null) {for (LazyInitializationExcludeFilter filter : filters) {// 如果当前过滤器认为bean应被排除，则直接返回trueif (filter.isExcluded(beanName, beanDefinition, beanType)) {return true;}}}// 如果没有过滤器认为bean应被排除，则返回falsereturn false;}@Overridepublic int getOrder() {return Ordered.HIGHEST_PRECEDENCE;}}

测试案例

java">class LazyInitializationExcludeFilterTests {@Testvoid forBeanTypesMatchesTypes() {// 创建一个LazyInitializationExcludeFilter，排除CharSequence和Number类型的beanLazyInitializationExcludeFilter filter = LazyInitializationExcludeFilter.forBeanTypes(CharSequence.class,Number.class);// 定义一个测试用的bean名称String beanName = "test";// 模拟一个BeanDefinition对象BeanDefinition beanDefinition = mock(BeanDefinition.class);// 验证filter是否正确排除了CharSequence类型System.out.println("验证filter是否正确排除了CharSequence类型:"+filter.isExcluded(beanName, beanDefinition, CharSequence.class));// 验证filter是否正确排除了String类型（CharSequence的子类型）System.out.println("验证filter是否正确排除了String类型（CharSequence的子类型）:"+filter.isExcluded(beanName, beanDefinition, String.class));// 验证filter是否正确排除了StringBuilder类型（CharSequence的子类型）System.out.println("验证filter是否正确排除了StringBuilder类型（CharSequence的子类型）:"+filter.isExcluded(beanName, beanDefinition, StringBuilder.class));// 验证filter是否正确排除了Number类型System.out.println("验证filter是否正确排除了Number类型:"+filter.isExcluded(beanName, beanDefinition, Number.class));// 验证filter是否正确排除了Long类型（Number的子类型）System.out.println("验证filter是否正确排除了Long类型（Number的子类型）:"+filter.isExcluded(beanName, beanDefinition, Long.class));// 验证filter是否正确不排除Boolean类型（非Number类型）System.out.println("验证filter是否正确不排除Boolean类型（非Number类型）:"+filter.isExcluded(beanName, beanDefinition, Boolean.class));}}

测试结果

验证filter是否正确排除了CharSequence类型:true
验证filter是否正确排除了String类型（CharSequence的子类型）:true
验证filter是否正确排除了StringBuilder类型（CharSequence的子类型）:true
验证filter是否正确排除了Number类型:true
验证filter是否正确排除了Long类型（Number的子类型）:true
验证filter是否正确不排除Boolean类型（非Number类型）:false