点此返回

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//模拟 @ComponentScan 注解的解析
//1、让自定义类实现 BeanDefinitionRegistryPostProcessor 接口
//		并重写 postProcessBeanFactory 方法
public class ComponentScanPostProcessor implements BeanDefinitionRegistryPostProcessor {
    @Override // context.refresh
    public void postProcessBeanFactory
        (ConfigurableListableBeanFactory configurableListableBeanFactory)
        throws BeansException {
        
        try {
            //2、使用 AnnotationUtils 工具类从Config类中找到 @ComponentScan 注解对象
            ComponentScan componentScan = AnnotationUtils
                .findAnnotation(Config.class, ComponentScan.class);
            if (componentScan != null) {
                //3、不为空，获取包名（包名转换为classpath下的资源路径）
                //	com.itheima.a05.component 
                //	-> classpath*:com/itheima/a05/component/**/*.class
                for (String p : componentScan.basePackages()) {
                    String path = "classpath*:" + p.replace(".", "/") + "/**/*.class";
                    
                    //4、读取类的元信息
                    CachingMetadataReaderFactory factory = 
                        new CachingMetadataReaderFactory();
                    Resource[] resources = 
                        new PathMatchingResourcePatternResolver().getResources(path);
                    AnnotationBeanNameGenerator generator =
                        new AnnotationBeanNameGenerator();
                    
                    for (Resource resource : resources) {
                        MetadataReader reader = factory.getMetadataReader(resource);
                        //5、判断是否间接或者直接加了@Component注解
                        if (reader.getAnnotationMetadata()
                            		  	.hasMetaAnnotation(Component.class.getName())
                            		   	|| 
                           	 reader.getAnnotationMetadata()
                            			.hasAnnotation(Component.class.getName())) {
                            
                            //6、创建一个BeanDefinition
                            AbstractBeanDefinition bd = BeanDefinitionBuilder
                                .genericBeanDefinition(reader
                                                       	.getClassMetadata()
                                                       	.getClassName())
                                						.getBeanDefinition();
                            if (configurableListableBeanFactory instanceof 
                                DefaultListableBeanFactory beanFactory) {
                                //7、将BeanDefinition加入到Bean工厂
                                String beanName = generator.generateBeanName(bd, beanFactory);
                                beanFactory.registerBeanDefinition(beanName,bd);
                            }
                        }
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

当其他类使用时，只需要调用 context的 registerBean方法，并传入自定义类的.class即可

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GenericApplicationContext context = new GenericApplicationContext();
context.registerBean(ComponentScanPostProcessor.class);
//初始化容器
context.refresh();
//for (String name : context.getBeanDefinitionNames()) {
//    System.out.println(name);
//}
//销毁容器
context.close();