BeanDefinition接口

代码片段

public interface BeanDefinition {// ...void setScope(@Nullable String scope);@NullableString getScope();void setLazyInit(boolean lazyInit);boolean isLazyInit();void setDependsOn(@Nullable String... dependsOn);@NullableString[] getDependsOn();boolean isSingleton();boolean isPrototype();boolean isAbstract();// ...
}

作用

存储Bean的定义信息，Spring通过Bean对应的BeanDefinition中的信息来判断该Bean是否单例，是否懒加载，是否抽象，是否依赖于其它的Bean等等

BeanDefinitionRegistry接口

代码片段

public interface BeanDefinitionRegistry extends AliasRegistry {// 往容器中添加BeanDefinitionvoid registerBeanDefinition(String beanName, BeanDefinition beanDefinition)throws BeanDefinitionStoreException;// 删除容器中指定的BeanDefinitionvoid removeBeanDefinition(String beanName) throws NoSuchBeanDefinitionException;// 获取容器中指定的BeanDefinitionBeanDefinition getBeanDefinition(String beanName) throws NoSuchBeanDefinitionException;// 判断容器中是否包含指定的BeanDefinitionboolean containsBeanDefinition(String beanName);// 获取容器中所有BeanDefinition的nameString[] getBeanDefinitionNames();// 统计容器中BeanDefinition的个数int getBeanDefinitionCount();// ...}

作用

提供对Spring容器中BeanDefinition进行操作的方法

RootBeanDefinition实现类

public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(BeanDefinitionRegistry registry, @Nullable Object source) {// ...// 这里Spring使用了RootBeanDefinition将内部组件Bean对象的BeanDefinition添加到容器中if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);def.setSource(source);beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));}// ...
}private static BeanDefinitionHolder registerPostProcessor(BeanDefinitionRegistry registry, RootBeanDefinition definition, String beanName) {// ...// 添加BeanDefinition到Spring容器中registry.registerBeanDefinition(beanName, definition);// ...}

GenericBeanDefinition实现类

/*** 普通Java类，没有加任何注解*/
public class Teacher {
}

public class SpringMain {public static void main(String[] args) {// Spring容器DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();// 构建GenericBeanDefinition对象GenericBeanDefinition beanDefinition = new GenericBeanDefinition();beanDefinition.setBeanClass(Teacher.class);// 将GenericBeanDefinition放入Spring容器beanFactory.registerBeanDefinition("teacher", beanDefinition);// 从容器中获取Bean对象Teacher teacherBean = beanFactory.getBean(Teacher.class);// 获取到Bean对象：xxxx.Teacher@279ad2e3System.out.println(teacherBean);}
}