Spring Data Redis中Hash结构操作技巧与最佳实践

@Autowired
private StringRedisTemplate stringRedisTemplate;

public class User {
    private String id;
    private String name;
    private String email;
    private Integer age;
    // getter/setter...
}

@Component
public class UserRedisService {
    @Autowired
    private StringRedisTemplate redisTemplate;
    private static final String USER_HASH_PREFIX = "user:";
    // 保存用户（全量覆盖）
    public void saveUser(User user) {
        String key = USER_HASH_PREFIX + user.getId();
        Map<String, String> userMap = new HashMap<>();
        userMap.put("name", user.getName());
        userMap.put("email", user.getEmail());
        userMap.put("age", String.valueOf(user.getAge()));
        redisTemplate.opsForHash().putAll(key, userMap);
        // 设置过期时间（可选）
        redisTemplate.expire(key, 2, TimeUnit.HOURS);
    }
    // 更新单个字段（如修改邮箱）
    public void updateEmail(String userId, String newEmail) {
        redisTemplate.opsForHash().put(USER_HASH_PREFIX + userId, "email", newEmail);
    }
    // 获取用户完整信息
    public User getUser(String userId) {
        String key = USER_HASH_PREFIX + userId;
        Map<Object, Object> entries = redisTemplate.opsForHash().entries(key);
        if (entries.isEmpty()) {
            return null; // 缓存未命中
        }
        User user = new User();
        user.setId(userId);
        user.setName((String) entries.get("name"));
        user.setEmail((String) entries.get("email"));
        user.setAge(Integer.parseInt((String) entries.get("age")));
        return user;
    }
    // 获取单个字段（如只查用户名）
    public String getUserName(String userId) {
        return (String) redisTemplate.opsForHash().get(USER_HASH_PREFIX + userId, "name");
    }
    // 删除用户
    public void deleteUser(String userId) {
        redisTemplate.delete(USER_HASH_PREFIX + userId);
    }
}

// 获取多个用户的姓名
List<String> userIds = Arrays.asList("1001", "1002", "1003");
List<String> names = userIds.stream()
    .map(id -> (String) redisTemplate.opsForHash().get("user:" + id, "name"))
    .collect(Collectors.toList());

@Autowired
private RedisTemplate<String, String> redisTemplate; // 注意类型
public List<String> getNamesInPipeline(List<String> userIds) {
    return redisTemplate.executePipelined((RedisCallback<String>) connection -> {
        for (String id : userIds) {
            connection.hGet(("user:" + id).getBytes(), "name".getBytes());
        }
        return null;
    });
}

// 错误：直接强转
Integer age = (Integer) redisTemplate.opsForHash().get("user:1001", "age"); // ClassCastException!

String ageStr = (String) redisTemplate.opsForHash().get("user:1001", "age");
Integer age = Integer.valueOf(ageStr);