Spring Core面试题

基础概念

Q1: Spring的核心特性有哪些？

public class SpringCoreBasicDemo {// 1. IoC容器public class IoCExample {public void iocDemo() {// XML配置@Configurationpublic class AppConfig {@Beanpublic UserService userService() {return new UserService(userRepository());}@Beanpublic UserRepository userRepository() {return new JdbcUserRepository();}}// 注解配置@Componentpublic class UserService {private final UserRepository userRepository;@Autowiredpublic UserService(UserRepository userRepository) {this.userRepository = userRepository;}}}}// 2. AOP实现public class AOPExample {public void aopDemo() {@Aspect@Componentpublic class LoggingAspect {@Around("execution(* com.example.service.*.*(..))")public Object logMethod(ProceedingJoinPoint joinPoint) throws Throwable {String methodName = joinPoint.getSignature().getName();logger.info("Before method: " + methodName);Object result = joinPoint.proceed();logger.info("After method: " + methodName);return result;}@AfterThrowing(pointcut = "execution(* com.example.service.*.*(..))",throwing = "ex")public void logException(Exception ex) {logger.error("Exception: " + ex.getMessage());}}}}
}

Q2: Spring的Bean生命周期是怎样的？

public class BeanLifecycleDemo {// 1. Bean定义public class BeanDefinitionExample {public void beanDefDemo() {@Componentpublic class LifecycleBean implements InitializingBean, DisposableBean, BeanFactoryAware, BeanNameAware {@Overridepublic void setBeanFactory(BeanFactory beanFactory) {// BeanFactory回调}@Overridepublic void setBeanName(String name) {// Bean名称回调}@PostConstructpublic void init() {// 初始化方法}@Overridepublic void afterPropertiesSet() {// 属性设置后回调}@PreDestroypublic void cleanup() {// 销毁前回调}@Overridepublic void destroy() {// 销毁方法}}}}// 2. Bean后处理器public class BeanPostProcessorExample {public void postProcessorDemo() {@Componentpublic class CustomBeanPostProcessor implements BeanPostProcessor {@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) {if (bean instanceof LifecycleBean) {// 初始化前处理}return bean;}@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) {if (bean instanceof LifecycleBean) {// 初始化后处理}return bean;}}}}
}

高级特性

Q3: Spring的事务管理是怎样的？

public class TransactionDemo {// 1. 声明式事务public class DeclarativeTransactionExample {public void transactionDemo() {@Configuration@EnableTransactionManagementpublic class TransactionConfig {@Beanpublic PlatformTransactionManager transactionManager(DataSource dataSource) {return new DataSourceTransactionManager(dataSource);}}@Service@Transactionalpublic class UserService {@Transactional(propagation = Propagation.REQUIRED,isolation = Isolation.READ_COMMITTED,rollbackFor = Exception.class)public void createUser(User user) {userRepository.save(user);emailService.sendWelcomeEmail(user);}@Transactional(readOnly = true)public User getUser(Long id) {return userRepository.findById(id).orElseThrow(() -> new UserNotFoundException(id));}}}}// 2. 编程式事务public class ProgrammaticTransactionExample {public void programmaticTransactionDemo() {@Servicepublic class UserService {private final PlatformTransactionManager transactionManager;private final UserRepository userRepository;public void createUser(User user) {TransactionTemplate template = new TransactionTemplate(transactionManager);template.execute(new TransactionCallback<Void>() {@Overridepublic Void doInTransaction(TransactionStatus status) {try {userRepository.save(user);emailService.sendWelcomeEmail(user);return null;} catch (Exception ex) {status.setRollbackOnly();throw ex;}}});}}}}
}

Q4: Spring的事件机制是怎样的？

public class EventDemo {// 1. 事件定义public class EventDefinitionExample {public void eventDefDemo() {// 自定义事件public class UserCreatedEvent extends ApplicationEvent {private final User user;public UserCreatedEvent(Object source, User user) {super(source);this.user = user;}public User getUser() {return user;}}// 事件发布者@Servicepublic class UserService {private final ApplicationEventPublisher eventPublisher;@Autowiredpublic UserService(ApplicationEventPublisher eventPublisher) {this.eventPublisher = eventPublisher;}public void createUser(User user) {userRepository.save(user);eventPublisher.publishEvent(new UserCreatedEvent(this, user));}}}}// 2. 事件监听public class EventListenerExample {public void eventListenerDemo() {@Componentpublic class UserEventListener {@EventListenerpublic void handleUserCreatedEvent(UserCreatedEvent event) {User user = event.getUser();// 处理用户创建事件}@EventListener@Asyncpublic void handleAsyncEvent(AsyncEvent event) {// 异步处理事件}@TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT)public void handleTransactionalEvent(TransactionalEvent event) {// 事务提交后处理事件}}}}
}

Q5: Spring的缓存机制是怎样的？

public class CacheDemo {// 1. 缓存配置public class CacheConfigExample {public void cacheConfigDemo() {@Configuration@EnableCachingpublic class CacheConfig {@Beanpublic CacheManager cacheManager() {SimpleCacheManager cacheManager = new SimpleCacheManager();cacheManager.setCaches(Arrays.asList(new ConcurrentMapCache("users"),new ConcurrentMapCache("roles")));return cacheManager;}@Beanpublic KeyGenerator keyGenerator() {return new KeyGenerator() {@Overridepublic Object generate(Object target, Method method, Object... params) {return target.getClass().getSimpleName() + ":" + method.getName() + ":" + Arrays.toString(params);}};}}}}// 2. 缓存使用public class CacheUsageExample {public void cacheUsageDemo() {@Servicepublic class UserService {@Cacheable(value = "users",key = "#id",condition = "#id != null",unless = "#result == null")public User getUser(Long id) {return userRepository.findById(id).orElse(null);}@CachePut(value = "users",key = "#user.id")public User updateUser(User user) {return userRepository.save(user);}@CacheEvict(value = "users",key = "#id")public void deleteUser(Long id) {userRepository.deleteById(id);}@CacheEvict(value = "users",allEntries = true)public void clearCache() {// 清除所有缓存}}}}
}