Spring Core面试题
基础概念
Q1: Spring的核心特性有哪些？
java
public class SpringCoreBasicDemo {
// 1. IoC容器
public class IoCExample {
public void iocDemo() {
// XML配置
@Configuration
public class AppConfig {
@Bean
public UserService userService() {
return new UserService(userRepository());
}
@Bean
public UserRepository userRepository() {
return new JdbcUserRepository();
}
}
// 注解配置
@Component
public class UserService {
private final UserRepository userRepository;
@Autowired
public UserService(UserRepository userRepository) {
this.userRepository = userRepository;
}
}
}
}
// 2. AOP实现
public class AOPExample {
public void aopDemo() {
@Aspect
@Component
public 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？
java
public class BeanLifecycleDemo {
// 1. Bean定义
public class BeanDefinitionExample {
public void beanDefDemo() {
@Component
public class LifecycleBean implements
InitializingBean,
DisposableBean,
BeanFactoryAware,
BeanNameAware {
@Override
public void setBeanFactory(BeanFactory beanFactory) {
// BeanFactory回调
}
@Override
public void setBeanName(String name) {
// Bean名称回调
}
@PostConstruct
public void init() {
// 初始化方法
}
@Override
public void afterPropertiesSet() {
// 属性设置后回调
}
@PreDestroy
public void cleanup() {
// 销毁前回调
}
@Override
public void destroy() {
// 销毁方法
}
}
}
}
// 2. Bean后处理器
public class BeanPostProcessorExample {
public void postProcessorDemo() {
@Component
public class CustomBeanPostProcessor
implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(
Object bean, String beanName) {
if (bean instanceof LifecycleBean) {
// 初始化前处理
}
return bean;
}
@Override
public 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？
java
public class TransactionDemo {
// 1. 声明式事务
public class DeclarativeTransactionExample {
public void transactionDemo() {
@Configuration
@EnableTransactionManagement
public class TransactionConfig {
@Bean
public PlatformTransactionManager transactionManager(
DataSource dataSource) {
return new DataSourceTransactionManager(dataSource);
}
}
@Service
@Transactional
public 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() {
@Service
public 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>() {
@Override
public 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？
java
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
@Service
public class UserService {
private final ApplicationEventPublisher eventPublisher;
@Autowired
public 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() {
@Component
public class UserEventListener {
@EventListener
public void handleUserCreatedEvent(
UserCreatedEvent event) {
User user = event.getUser();
// 处理用户创建事件
}
@EventListener
@Async
public 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？
java
public class CacheDemo {
// 1. 缓存配置
public class CacheConfigExample {
public void cacheConfigDemo() {
@Configuration
@EnableCaching
public class CacheConfig {
@Bean
public CacheManager cacheManager() {
SimpleCacheManager cacheManager =
new SimpleCacheManager();
cacheManager.setCaches(Arrays.asList(
new ConcurrentMapCache("users"),
new ConcurrentMapCache("roles")));
return cacheManager;
}
@Bean
public KeyGenerator keyGenerator() {
return new KeyGenerator() {
@Override
public 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() {
@Service
public 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
}
}
}
}
}面试关键点
- 理解Spring的核心特性
- 掌握Bean生命周期
- 熟悉事务管理机制
- 了解事件处理机制
- 掌握缓存实现原理
- 理解AOP的实现
- 注意性能优化
- 关注最佳实践