我有一个EmployeeDaoImpl类，它有一个**saveEmployee方法，它使用hashOperations的putIfAbsent方法在Redis中存储JSON**字符串。

@Service
public class EmployeeDaoImpl implements IEmployeeDao {

    private static final String MAPPING_KEY = "EMPLOYEES_REG_TEMP_RECORDS";
    
    private final ObjectMapper objectMapper;
    private final StringRedisTemplate stringRedisTemplate;
    @Resource(name = "stringRedisTemplate")  // 'stringRedisTemplate' is defined as a Bean in AppConfig.java
    private HashOperations<String, String, String> hashOperations;
    
    public EmployeeDaoImpl(ObjectMapper objectMapper, StringRedisTemplate stringRedisTemplate) {
        this.objectMapper = objectMapper;
        this.stringRedisTemplate = stringRedisTemplate;
    }
    
    @Override
    public void saveEmployee(Employee emp) throws JsonProcessingException {
        String json = objectMapper.writeValueAsString(emp);
        hashOperations.putIfAbsent(MAPPING_KEY, emp.getRequestRefId(), json);
    }

}

这张截图是Redis

中员工记录的保存方式
我可以通过这种方式使密钥过期

stringRedisTemplate.expire(key, 30, TimeUnit.SECONDS)

但现在我希望能够为EMPLOYEES_REG_TEMP_RECORDS哈希键中的每个单行记录设置TTL，而不会使该键过期