从海量数据里查出某一固定前缀的key

   @Override
    @SuppressWarnings("unchecked")
    public <T> Map<String, T> hScan(String key, String pattern) {
        final Map<String, T> scanResult = Maps.newHashMap();
        try (Cursor<Map.Entry<Object, Object>> cursor = template.opsForHash().scan(key, ScanOptions.scanOptions()
                .count(Integer.MAX_VALUE)
                .match(pattern)
                .build())) {
            while (cursor.hasNext()) {
                final Map.Entry<Object, Object> entry = cursor.next();
                scanResult.put(String.valueOf(entry.getKey()), (T) entry.getValue());
            }
        } catch (Exception e) {
            log.error(e.getMessage(), e);
        }
        return scanResult;
    }


  @Override
    public Set<String> scan(String pattern) {
        return template.execute((RedisCallback<Set<String>>) connection -> {
            Set<String> keysTmp = Sets.newHashSet();
            try (Cursor<byte[]> cursor = connection.scan(new ScanOptions.ScanOptionsBuilder()
                    .count(Integer.MAX_VALUE)
                    .match(pattern)
                    .build())) {
                while (cursor.hasNext()) {
                    keysTmp.add(new String(cursor.next()));
                }
            } catch (Exception e) {
                log.error(e.getMessage(), e);
            }
            return keysTmp;
        });
    }