Spring

Spring interview questions with detailed answers; how Spring resolves circular dependencies.

Spring core container, data access/integration, Web, AOP, Instrumentation, Test, and miscellaneous modules.

1. What ApplicationListener is 2. How to use the event-listener mechanism 3. References

1. Scope categories 2. Why prototype exists 3. References

1. Create the project 2. pom.xml 3. Code

1. Create the project 2. pom.xml 3. Code

Class inheritance diagram and principle analysis of Spring's AutowiredAnnotationBeanPostProcessor.

1. Enable transaction management. 2. TransactionManagementConfigurationSelector imports AutoProxyRegistrar and ProxyTransactionManagementConfiguration. 3. Study AutoProxyRegistrar. 4. Study ProxyTransactionManagementConfiguration and transaction interception.

1. Process 2. Usage 3. References

1. What AOP is 2. Implementation principle

1. Explanation of IoC 2. Implementation principle 3. Benefits of IoC

Common Spring annotations and Aware interfaces, including Configuration, ComponentScan, Bean, Scope, Lazy, Conditional, Import, Value, Autowired, Qualifier, Primary, and Profile.

1. What transaction propagation is. 1.1. Propagation behaviors including REQUIRED, SUPPORTS, MANDATORY, REQUIRES_NEW, NOT_SUPPORTED, and NEVER. 1.2. Notes. 2. References.

1. BeanFactory and ApplicationContext 2. References

Create a project, configure pom.xml, and use Spring transactions with DbConfig, TestService, and TestDao.

1. What a circular dependency is 2. What problems it causes 3. How to solve it 4. References

1. Use @DependsOn 2. References

1. Code to analyze 2. Create ApplicationContext and trace the refresh process

1. Code to study 2. Process BeanDefinitionRegistryPostProcessors 3. Process BeanFactoryPostProcessors

1. Code to study 2. Obtain BeanPostProcessors 3. Classify them 4-7. Register each group

Source tracing of finishBeanFactoryInitialization and preInstantiateSingletons through getBean, singleton lookup and creation, BeanPostProcessors, bean instantiation, property population, initialization, proxy creation, and destruction registration.

Spring IoC UML diagram

Enable AOP, register AspectJAnnotationAutoProxyCreator, and trace when ImportBeanDefinitionRegistrar.registerBeanDefinitions is called

Class hierarchy, call-stack analysis, BeanFactoryAware setBeanFactory, registration and initialization of AnnotationAwareAspectJAutoProxyCreator

Created on Monday, July 22, 2019. Source analysis of Spring AOP from @EnableAspectJAutoProxy through auto-proxy creation and target-method interceptor execution.

Trace postProcessBeforeInstantiation and postProcessAfterInitialization while creating singleton Beans

Trace to postProcessBeforeInstantiation, determine whether a proxy is needed, wrap the Bean with advisors, and create JDK/CGLIB proxies

Invoke Calc.div, enter the proxy intercept method, build the interceptor chain, and execute interceptors plus the target method