redis list類型命令的實現(xiàn)

更新時間：2023年07月20日 15:10:53 作者：不想睡覺的橘子君

本文主要介紹了redis list類型命令的實現(xiàn)，文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值，需要的朋友們下面隨著小編來一起學習學習吧

redis的list類型，可以存儲雙向鏈表作為value，key保留有head和tail指針可以指向雙向鏈表的頭和尾，因此可以直接從頭或尾對list進行操作。
全部命令如下：

127.0.0.1:6379> help @list
? BLMOVE source destination LEFT|RIGHT LEFT|RIGHT timeout
? summary: Pop an element from a list, push it to another list and return it; or block until one is available
? since: 6.2.0
? BLMPOP timeout numkeys key [key ...] LEFT|RIGHT [COUNT count]
? summary: Pop elements from a list, or block until one is available
? since: 7.0.0
? BLPOP key [key ...] timeout
? summary: Remove and get the first element in a list, or block until one is available
? since: 2.0.0
? BRPOP key [key ...] timeout
? summary: Remove and get the last element in a list, or block until one is available
? since: 2.0.0
? BRPOPLPUSH source destination timeout
? summary: Pop an element from a list, push it to another list and return it; or block until one is available
? since: 2.2.0
? LINDEX key index
? summary: Get an element from a list by its index
? since: 1.0.0
? LINSERT key BEFORE|AFTER pivot element
? summary: Insert an element before or after another element in a list
? since: 2.2.0
? LLEN key
? summary: Get the length of a list
? since: 1.0.0
? LMOVE source destination LEFT|RIGHT LEFT|RIGHT
? summary: Pop an element from a list, push it to another list and return it
? since: 6.2.0
? LMPOP numkeys key [key ...] LEFT|RIGHT [COUNT count]
? summary: Pop elements from a list
? since: 7.0.0
? LPOP key [count]
? summary: Remove and get the first elements in a list
? since: 1.0.0
? LPOS key element [RANK rank] [COUNT num-matches] [MAXLEN len]
? summary: Return the index of matching elements on a list
? since: 6.0.6
? LPUSH key element [element ...]
? summary: Prepend one or multiple elements to a list
? since: 1.0.0
? LPUSHX key element [element ...]
? summary: Prepend an element to a list, only if the list exists
? since: 2.2.0
? LRANGE key start stop
? summary: Get a range of elements from a list
? since: 1.0.0
? LREM key count element
? summary: Remove elements from a list
? since: 1.0.0
? LSET key index element
? summary: Set the value of an element in a list by its index
? since: 1.0.0
? LTRIM key start stop
? summary: Trim a list to the specified range
? since: 1.0.0
? RPOP key [count]
? summary: Remove and get the last elements in a list
? since: 1.0.0
? RPOPLPUSH source destination
? summary: Remove the last element in a list, prepend it to another list and return it
? since: 1.2.0
? RPUSH key element [element ...]
? summary: Append one or multiple elements to a list
? since: 1.0.0
? RPUSHX key element [element ...]
? summary: Append an element to a list, only if the list exists
? since: 2.2.0

下面示例如下：

lpush：lpush key e1 e2 e3…將數(shù)據(jù)從頭那里推入list
lpop：lpop key，將數(shù)據(jù)從head彈出

這樣2個同向的命令組合起來，可以實現(xiàn)一個隊列。

反向的命令組合起來，可以實現(xiàn)一個棧。

127.0.0.1:6379> lpush k1 a b c d e
(integer) 5
127.0.0.1:6379> lpop k1
"e"
127.0.0.1:6379> lpop k1
"d"

lrange ：lrange key start end，展示key對應的從下標start到end的所有數(shù)據(jù)

127.0.0.1:6379> lrange k1 0 -1
1) "c"
2) "b"
3) "a"

lindex：lindex key index ，返回key對應的List指定index位置的值

127.0.0.1:6379> lrange k1 0 -1
1) "f"
2) "e"
3) "d"
4) "c"
5) "b"
6) "a"
127.0.0.1:6379> lindex k1 1
"e"

lset：lset key index value，在key對應的list中的指定下標處替換為value

127.0.0.1:6379> lset k1 3 x
OK
127.0.0.1:6379> lrange k1 0 -1
1) "f"
2) "e"
3) "d"
4) "x"
5) "b"
6) "a"

lrem：lrem key num target，刪除key對應的list中的target元素，如果num大于0，從head開始刪num個。如果num小于0，從tail開始刪abs(num)個

127.0.0.1:6379> lrange k3 0 -1
 1) "d"
 2) "6"
 3) "a"
 4) "5"
 5) "c"
 6) "4"
 7) "a"
 8) "3"
 9) "b"
10) "2"
11) "a"
12) "1"
127.0.0.1:6379> lrem k3 2 a
(integer) 2
127.0.0.1:6379> lrange k3 0 -1
 1) "d"
 2) "6"
 3) "5"
 4) "c"
 5) "4"
 6) "3"
 7) "b"
 8) "2"
 9) "a"
10) "1"

linsert：linsert key before/after element value，在key對應的list中，在元素element（不是下標）之前或者之后，添加value

127.0.0.1:6379> lrange k3 0 -1
 1) "d"
 2) "6"
 3) "5"
 4) "c"
 5) "4"
 6) "3"
 7) "b"
 8) "2"
 9) "a"
10) "1"
127.0.0.1:6379> linsert k3 after 6 a
(integer) 11
127.0.0.1:6379> lrange k3 0 -1
 1) "d"
 2) "6"
 3) "a"
 4) "5"
 5) "c"
 6) "4"
 7) "3"
 8) "b"
 9) "2"
10) "a"
11) "1"

llen：llen key，返回長度
redis的List類型有很多關于下標的操作，也可以將其抽象為一個數(shù)組來使用。

127.0.0.1:6379> llen k3
(integer) 10

blpop：blpop key time，彈出指定key對應的list中的一個元素，如果list沒有元素或者不存在key對應的這個list，則阻塞等待time指定的時間，0表示一直等待，單位是s。

127.0.0.1:6379> blpop k1 0

阻塞期間如果list有了元素，則會中斷阻塞并彈出

127.0.0.1:6379> blpop k1 0
1) "k1"
2) "a"
(35.77s)

ltrim：ltrim key start end，刪除key對應的list start和end之外的兩端的元素

127.0.0.1:6379> lrange k4 0 -1
1) "f"
2) "e"
3) "d"
4) "c"
5) "b"
6) "a"
127.0.0.1:6379> ltrim k4 1 -2
OK
127.0.0.1:6379> lrange k4 0 -1
1) "e"
2) "d"
3) "c"
4) "b"

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