Spring Boot Redis：实体更新后如何从数据库取数？@CacheEvict使用困惑

我是Redis新手，这可能是个基础问题。我使用@Cacheable()和@CacheEvict()注解，当用户实体更新后，通过ID获取用户时仍会拿到缓存中的过时数据。我知道@CacheEvict()应该能解决这个问题，但我对它的作用感到困惑——使用它和不使用它的结果似乎一样，比如耗时3秒的长任务，使用该注解后还是需要3秒。

首次获取数据耗时3秒，再次获取同一数据仅需5毫秒（从Redis读取），但更新用户后再次获取会得到过时数据，导致数据不一致。

UserServiceImpl.java #

package com.example.demo.serviceImpl;

import lombok.AllArgsConstructor;
import com.example.demo.model.User;
import com.example.demo.repository.UserRepository;
import com.example.demo.service.UserService;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.util.List;

@Service
@EnableCaching
@AllArgsConstructor
public class UserServiceImpl implements UserService {

    private UserRepository userRepository;

    @Override
    public User createUser(User user) {
        return userRepository.save(user);
    }

    @Override
    @CacheEvict(value = "users")
    public User findUser(String userId) {
        doLongRunningTask();
        return userRepository.findById(userId).orElseThrow();
    }

    @Override
    @Cacheable(value = "users")
    public List<User> findAll() {
        return (List<User>) userRepository.findAll();
    }

    @Override
    @CacheEvict(value = "users", key = "#user.id")
    public User updateUser(String userId, User user) {
        doLongRunningTask();
        user.setUpdatedAt(LocalDateTime.now());
        return userRepository.save(user);
    }

    @Override
    @CacheEvict(value = "users", key = "#userId")
    public void deleteUser(String userId) {
        userRepository.deleteById(userId);
    }

    private void doLongRunningTask() {
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}

RedisConfig.java #

package com.example.demo.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;

import java.time.Duration;

import static org.springframework.data.redis.serializer.RedisSerializationContext.SerializationPair.fromSerializer;

@Configuration
public class RedisConfig {

    @Value("${redis.host}")
    private String redisHost;

    @Value("${redis.port}")
    private int redisPort;

    @Bean
    public LettuceConnectionFactory redisConnectionFactory() {
        RedisStandaloneConfiguration configuration = new RedisStandaloneConfiguration();
        configuration.setHostName(redisHost);
        configuration.setPort(redisPort);
        return new LettuceConnectionFactory(configuration);
    }

    @Bean
    public RedisCacheManager cacheManager() {
        RedisCacheConfiguration cacheConfig = myDefaultCacheConfig(Duration.ofMinutes(10)).disableCachingNullValues();

        return RedisCacheManager
                .builder(redisConnectionFactory())
                .cacheDefaults(cacheConfig)
                .withCacheConfiguration("users", myDefaultCacheConfig(Duration.ofMinutes(5)))
                .build();
    }

    private RedisCacheConfiguration myDefaultCacheConfig(Duration duration) {
        return RedisCacheConfiguration
                .defaultCacheConfig()
                .entryTtl(duration)
                .serializeValuesWith(fromSerializer(new GenericJackson2JsonRedisSerializer()));
    }

}

更新补充内容 #

model/User.java #

package com.example.demo.model;

import lombok.*;
import org.springframework.data.annotation.Id;
import org.springframework.data.redis.core.RedisHash;

@Data
@Builder
@RedisHash("user")
public class User {

    @Id
    private String id;
    private String name;
    private Integer age;

}

dto/UserDTO.java #

package com.example.demo.dto;

import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class UserDTO implements Serializable {

    @JsonProperty(value = "id")
    private String id;

    @JsonProperty(value = "name")
    private String name;

    @JsonProperty(value = "age")
    private Integer age;

}

感谢@Max Kozlov的帮助，现在该DTO类已实现Serializable，确保Redis缓存正常工作。

更新后的RedisCacheConfig.java #

package com.example.demo.config;

import com.example.demo.handler.DefaultCacheErrorHandler;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.CachingConfigurer;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.cache.interceptor.CacheErrorHandler;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;

import java.time.Duration;

@Configuration
@EnableCaching
public class RedisCacheConfig implements CachingConfigurer {

    @Value("${redis.host}")
    private String redisHost;

    @Value("${redis.port}")
    private int redisPort;

    @Bean
    public LettuceConnectionFactory redisConnectionFactory() {
        RedisStandaloneConfiguration configuration = new RedisStandaloneConfiguration();
        configuration.setHostName(redisHost);
        configuration.setPort(redisPort);
        return new LettuceConnectionFactory(configuration);
    }

    @Bean
    public RedisCacheConfiguration redisCacheConfiguration() {
        return RedisCacheConfiguration
                .defaultCacheConfig()
                .entryTtl(Duration.ofMinutes(15));
    }

    @Bean
    @Override
    public CacheErrorHandler errorHandler() {
        return new DefaultCacheErrorHandler();
    }

    @Bean("longLifeCacheManager")
    public CacheManager longLifeCacheManager() {
        RedisCacheConfiguration defaultConfiguration = RedisCacheConfiguration
                .defaultCacheConfig()
                .entryTtl(Duration.ofDays(90));

        return RedisCacheManager
                .RedisCacheManagerBuilder
                .fromConnectionFactory(redisConnectionFactory())
                .cacheDefaults(defaultConfiguration)
                .build();
    }

    @Primary
    @Bean("shortLifeCacheManager")
    public CacheManager shortLifeCacheManager() {
        RedisCacheConfiguration defaultConfiguration = RedisCacheConfiguration
                .defaultCacheConfig()
                .entryTtl(Duration.ofDays(1));

        return RedisCacheManager
                .RedisCacheManagerBuilder
                .fromConnectionFactory(redisConnectionFactory())
                .cacheDefaults(defaultConfiguration)
                .build();
    }

}

内容的提问来源于stack exchange，提问作者busuu