SpringBoot中请求级缓存4种高效方案对比的终极指南

// 缓存工具类
public class RequestCache {
    private static final ThreadLocal<Map<String, Object>> cache = new ThreadLocal<>();

    public static void put(String key, Object value) {
        if (cache.get() == null) {
            cache.set(new HashMap<>());
        }
        cache.get().put(key, value);
    }

    public static Object get(String key) {
        return cache.get() != null ? cache.get().get(key) : null;
    }

    public static void clear() {
        cache.remove();
    }
}

// Filter配置
@Configuration
public class RequestCacheFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
        try {
            chain.doFilter(request, response);
        } finally {
            RequestCache.clear(); // 请求结束自动清除
        }
    }
}

// 自定义注解
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface RequestCached {
    String key();
}

// AOP切面
@Aspect
@Component
public class RequestCacheAspect {
    private final ThreadLocal<Map<String, Object>> cache = new ThreadLocal<>();

    @Before("@annotation(requestCached)")
    public void before(JoinPoint joinPoint, RequestCached requestCached) {
        String key = requestCached.key();
        if (cache.get() == null) {
            cache.set(new HashMap<>());
        }
    }

    @AfterReturning(pointcut = "@annotation(requestCached)", returning = "result")
    public void afterReturning(JoinPoint joinPoint, RequestCached requestCached, Object result) {
        String key = requestCached.key();
        cache.get().put(key, result);
    }

    @After("execution(* *(..)) && @annotation(requestCached)")
    public void after(JoinPoint joinPoint, RequestCached requestCached) {
        cache.remove(); // 请求结束清除
    }
}

@Service
public class UserService {
    @Cacheable(value = "request", key = "#userId")
    public User getUserById(String userId) {
        // 模拟数据库查询
        return userRepository.findById(userId);
    }
}

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @GetMapping("/user/{id}")
    public User getUser(@PathVariable String id) {
        User user = userService.getUserById(id);
        // 手动清除缓存（需配合Filter或AOP）
        return user;
    }
}

// Filter配置
@Configuration
public class RequestCacheFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
        Map<String, Object> cache = new HashMap<>();
        request.setAttribute("requestCache", cache); // 绑定到请求上下文
        try {
            chain.doFilter(request, response);
        } finally {
            cache.clear(); // 请求结束清除
        }
    }
}

// 业务代码
@RestController
public class UserController {
    @GetMapping("/user/{id}")
    public User getUser(@PathVariable String id, HttpServletRequest request) {
        Map<String, Object> cache = (Map<String, Object>) request.getAttribute("requestCache");
        User user = (User) cache.get("user_" + id);
        if (user == null) {
            user = userRepository.findById(id);
            cache.put("user_" + id, user);
        }
        return user;
    }
}

// 错误示例：未隔离线程池导致缓存污染
@Bean
public Executor taskExecutor() {
    return Executors.newFixedThreadPool(10); // 默认线程池
}

@Bean
public Executor taskExecutor() {
    ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setThreadNamePrefix("RequestCache-");
    executor.setTaskDecorator(new RequestCacheTaskDecorator()); // 自定义装饰器隔离缓存
    return executor;
}

// 错误示例：硬编码缓存键
cache.put("user_" + id, user);

// 使用枚举统一管理缓存键
public enum CacheKey {
    USER("user_"), ORDER("order_");
    private final String prefix;
    CacheKey(String prefix) { this.prefix = prefix; }
    public String getKey(String id) { return prefix + id; }
}

// 错误示例：未捕获异常导致缓存残留
try {
    User user = getUserFromDB(id);
    cache.put("user_" + id, user);
} catch (Exception e) {
    log.error("Query failed", e);
}

// 使用Finally确保清除
try {
    User user = getUserFromDB(id);
    cache.put("user_" + id, user);
} finally {
    cache.clear(); // 或仅清除特定键
}