Hash操作
* 看别人的总没有自己实操来的印象深刻
redis的五大数据类型 字符串、列表、集合、有序集合、哈希
redis的哈希类型指的是键值本身又是一个键值对结构：
如：vaule = {{key1,value1},{key2,value2}...{keyn,valuen}}
相对于java可以理解为map：Key=>(Map<HK,HV>)
哈希类型的内部编码有两种：
ziplist（压缩列表）：当哈希类型元素个数小于hash-max-ziplist-entries配置（默认512个）、同时所有值都小于hash-max-ziplist-value配置（默认64字节）时，Redis会使用ziplist作为哈希的内部实现，ziplist使用更加紧凑的结构实现多个元素的连续存储，所以在节省内存方面比hashtable更加优秀。
hashtable（哈希表）：当哈希类型无法满足ziplist的条件时，Redis会使用hashtable作为哈希的内部实现，因为此时ziplist的读写效率会下降，而hashtable的读写时间复杂度为O（1）。
在redis开发与运维中的图解：
redis对哈希的命令在redisTemplate中都有映射，见下方表：
redisTemplate
//以下表格使用hash代替redisTemplate.opsForHash() :
HashOperations hash = redisTemplate.opsForHash();
| 命令 | 操作 | 返回值 |
|---|---|---|
| hash.delete(H key, Object... hashKeys) | 删除，可以传入多个map的key【hdel】 | Long |
| hash.hasKey(key, hashKey) | 查看hash中的某个hashKey是否存在【hexists】 | Boolean |
| hash.get(key, hashKey) | 获取值【hget】 | Object（HV 泛型约束对象） |
| hash.multiGet(H key, Collection<HK> hashKeys) | 批量获取集合中的key对应的值【hmget】 | List<HV> |
| hash.increment(H key, HK hashKey, long delta) | 对值进行+(delta值)操作【】 | Long |
| hash.increment(H key, HK hashKey, double delta) | ~ | double |
| hash.keys(key) | 返回map内hashKey的集合【hkeys】 | Set<HK> |
| hash.lengthOfValue(H key, HK hashKey) | 返回查询键关联的值的长度，为null则返回0【hstrlen】 | Long |
| hash.size(H key) | 获取hashKey的个数【hlen】 | Long |
| hash.putAll(H key, Map<? extends HK, ? extends HV> m) | 相当于map的putAll【hmset】 | void |
| hash.put(H key, HK hashKey, HV value) | 设置值，添加hashKey-value，hashKay相当于map的key 【hset】 | void |
| hash.putIfAbsent(H key, HK hashKey, HV value) | 仅当hashKey不存在时设置值 | Boolean |
| hash.values(key) | 返回value的集合【hvals】 | List<HV> |
| hase.entries(H key) | 获取map【hgetall】 | Map<HK, HV> |
| hash.scan(H key, ScanOptions options) | 基于游标的迭代查询【hscan】 | Cursor<Map.Entry<HK, HV>>（返回的Cursor要手动关闭，见下面示例2） |
| hash.getOperations() | 返回RedisOperation，它就是redis操作的接口 | RedisOperations<H, ?> |
对于命令的时间复杂度见下表：
示例测试操作1：
//key String k = "phoneMap"; //map的key String hashKey = "13838383838"; Map<String, String> phoneMap = new HashMap<>(); phoneMap.put("13838383839","1"); phoneMap.put(hashKey,"2"); //添加map //redisTemplate.opsForHash().putAll(k, phoneMap); //在key的value中添加单个hash值 redisTemplate.opsForHash().put(k, "19199999999","2"); //获取map Map m1 = redisTemplate.opsForHash().entries(k); Object o = redisTemplate.opsForHash().get(k, hashKey); log.info("get key:{}", o); log.info("map:{}", m1);
log打印的结果：
2019-12-13 15:45:36.836 INFO 4156 --- [ main] : get key:null
2019-12-13 15:45:36.836 INFO 4156 --- [ main] : map:{13838121333=1, 13838121556=2, 19199999999=2}
如果这里使用了redisTemplate.opsForHash().putAll(k, phoneMap); ，则get key打印的结果就是2。这里打印的map是包含之前测试的值。
示例测试操作2：
@Test public void hashTest(){ String k = "phoneMap"; String hashKey = "19199999999"; HashOperations<String, String, String> hash = redisTemplate.opsForHash(); hash.increment(k,hashKey,1); log.info("19199999999:{}", hash.get(k,hashKey)); Set set = hash.keys(k); log.info("phoneMap:{}", set); Long sizeLong = hash.size(k); log.info("sizeLong:{}",sizeLong); Cursor<Map.Entry<String, String>> cursor = hash.scan(k,ScanOptions.scanOptions().count(1000).build()); while (cursor.hasNext()){ Map.Entry<String, String> entry = cursor.next(); log.info("entry:{}:{}", entry.getKey(), entry.getValue()); } try { if (!cursor.isClosed()){ cursor.close(); } } catch (IOException e) { log.error("关闭cursor异常"); e.printStackTrace(); } }
打印结果：
2019-12-13 16:59:35.573 INFO 1540 --- [ main] : 19199999999:6
2019-12-13 16:59:35.577 INFO 1540 --- [ main] : phoneMap:[13838121333, 13838121556, 19199999999, 13838383839, 13838383838]
2019-12-13 16:59:35.578 INFO 1540 --- [ main] : sizeLong:5
2019-12-13 16:59:35.587 INFO 1540 --- [ main] : entry:13838121373:1
2019-12-13 16:59:35.587 INFO 1540 --- [ main] : entry:13838121556:2
2019-12-13 16:59:35.587 INFO 1540 --- [ main] : entry:19199999999:6
2019-12-13 16:59:35.587 INFO 1540 --- [ main] : entry:13838383839:1
2019-12-13 16:59:35.587 INFO 1540 --- [ main] : entry:13838383838:2
# 使用文件形式展示：
private final String REDIS_PHONE_CONUM_PREFIX_KEY = "phoneSms:Check";
/**
* 添加手机号发送次数
* @param phone
* @return
*/
public void setPhoneSmsCountInc(String phone){
HashOperations hash = redisTemplate.opsForHash();
if (!redisTemplate.hasKey(REDIS_PHONE_CONUM_PREFIX_KEY)){
//设置过期key时间
redisTemplate.expire(REDIS_PHONE_CONUM_PREFIX_KEY, 24 * 60 * 60, TimeUnit.SECONDS);
}
hash.increment(REDIS_PHONE_CONUM_PREFIX_KEY, phone,1);
}
这是HashOperations的源码：
/* * Copyright 2011-2019 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.data.redis.core; import java.util.Collection; import java.util.List; import java.util.Map; import java.util.Set; import org.springframework.lang.Nullable; /** * Redis map specific operations working on a hash. * * @author Costin Leau * @author Christoph Strobl * @author Ninad Divadkar */ public interface HashOperations<H, HK, HV> { /** * Delete given hash {@code hashKeys}. * * @param key must not be {@literal null}. * @param hashKeys must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. */ Long delete(H key, Object... hashKeys); /** * Determine if given hash {@code hashKey} exists. * * @param key must not be {@literal null}. * @param hashKey must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. */ Boolean hasKey(H key, Object hashKey); /** * Get value for given {@code hashKey} from hash at {@code key}. * * @param key must not be {@literal null}. * @param hashKey must not be {@literal null}. * @return {@literal null} when key or hashKey does not exist or used in pipeline / transaction. */ @Nullable HV get(H key, Object hashKey); /** * Get values for given {@code hashKeys} from hash at {@code key}. * * @param key must not be {@literal null}. * @param hashKeys must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. */ List<HV> multiGet(H key, Collection<HK> hashKeys); /** * Increment {@code value} of a hash {@code hashKey} by the given {@code delta}. * * @param key must not be {@literal null}. * @param hashKey must not be {@literal null}. * @param delta * @return {@literal null} when used in pipeline / transaction. */ Long increment(H key, HK hashKey, long delta); /** * Increment {@code value} of a hash {@code hashKey} by the given {@code delta}. * * @param key must not be {@literal null}. * @param hashKey must not be {@literal null}. * @param delta * @return {@literal null} when used in pipeline / transaction. */ Double increment(H key, HK hashKey, double delta); /** * Get key set (fields) of hash at {@code key}. * * @param key must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. */ Set<HK> keys(H key); /** * Returns the length of the value associated with {@code hashKey}. If either the {@code key} or the {@code hashKey} * do not exist, {@code 0} is returned. * * @param key must not be {@literal null}. * @param hashKey must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. * @since 2.1 */ @Nullable Long lengthOfValue(H key, HK hashKey); /** * Get size of hash at {@code key}. * * @param key must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. */ Long size(H key); /** * Set multiple hash fields to multiple values using data provided in {@code m}. * * @param key must not be {@literal null}. * @param m must not be {@literal null}. */ void putAll(H key, Map<? extends HK, ? extends HV> m); /** * Set the {@code value} of a hash {@code hashKey}. * * @param key must not be {@literal null}. * @param hashKey must not be {@literal null}. * @param value */ void put(H key, HK hashKey, HV value); /** * Set the {@code value} of a hash {@code hashKey} only if {@code hashKey} does not exist. * * @param key must not be {@literal null}. * @param hashKey must not be {@literal null}. * @param value * @return {@literal null} when used in pipeline / transaction. */ Boolean putIfAbsent(H key, HK hashKey, HV value); /** * Get entry set (values) of hash at {@code key}. * * @param key must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. */ List<HV> values(H key); /** * Get entire hash stored at {@code key}. * * @param key must not be {@literal null}. * @return {@literal null} when used in pipeline / transaction. */ Map<HK, HV> entries(H key); /** * Use a {@link Cursor} to iterate over entries in hash at {@code key}. <br /> * <strong>Important:</strong> Call {@link Cursor#close()} when done to avoid resource leak. * * @param key must not be {@literal null}. * @param options * @return {@literal null} when used in pipeline / transaction. * @since 1.4 */ Cursor<Map.Entry<HK, HV>> scan(H key, ScanOptions options); /** * @return never {@literal null}. */ RedisOperations<H, ?> getOperations(); }