redis之list核心命令演示与细节探索
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
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
BRPOP key [key ...] timeout
移除并且得到集合中的最后一个元素,或者阻塞直到有一个元素(或者超时报错)
summary: Remove and get the last element in a list, or block until one is available
since: 2.0.0
> lrange test:list1 0 -1
> lrange test:list2 0 -1
list2_0
> lrange test:list3 0 -1
list3_0
> brpop test:list1 test:list2 test:list3 0
test:list2
list2_0
说明:
- test:list1中没有元素,test:list2中有元素,test:list3中有元素,brpop test:list1 test:list2 test:list3 0会依次检查test:list1,test:list2,test:list3三个list,如果有则从右边弹出元素,并返回弹出元素的key和弹出的元素
- 如果test:list1 test:list2 test:list3中都没有元素,会一直阻塞,直到其中有一个有元素,返回弹出元素的key和弹出的元素
- 超时时间单位为秒,0表示无限期阻塞
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
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
LPUSHX key element [element ...]
summary: Prepend an element to a list, only if the list exists
如果list存在,则从左边往里面添加元素
since: 2.2.0
# key test:list:lpushx 不存在
> exists test:list:lpushx
0
# 如果key不存在lpushx失败
> lpushx test:list:lpushx 0
0
# key test:list:lpushx 依然不存在
> exists test:list:lpushx
0
# lpush 一个元素使key test:list:lpushx 存在
> lpush test:list:lpushx 0
1
# key test:list:lpushx 存在
> exists test:list:lpushx
1
# 如果key test:list:lpushx 存在则lpushx成功
> lpush test:list:lpushx 1
2
> LRANGE test:list:lpushx 0 -1
1
0
LRANGE
LRANGE key start stop
summary: Get a range of elements from a list
since: 1.0.0
说明:
- 计算offset有两种方式
- 从头到尾,第一个元素的offset是0,第二个是1,以此类推
- 从尾到头计算,倒数第一个元素的offset是-1,倒数第二个元素是-2,以此类推
LREM
LREM key count element
summary: Remove elements from a list
从list中删除传入的元素
count=0时移除所有的
count>0时从左往右移除 count个
count<0时从右往左移除 -count个
since: 1.0.0
java
@Test
void listlrem() {
String key = "test:list";
redisTemplate.delete(key);
ListOperations<String, String> ops = redisTemplate.opsForList();
ops.leftPushAll(key,"v1","v2","v1","v3","v1","v1");
System.out.println(ops.range(key,0,-1));
int count = 0;
// int count = 2;
// int count = -2;
ops.remove(key,count,"v1");
System.out.println(ops.range(key,0,-1));
}count = 0时删除全部的v1
[v1, v1, v3, v1, v2, v1]
[v3, v2]
count = 2时从左往右删除2个v1
[v1, v1, v3, v1, v2, v1]
[v3, v1, v2, v1]
count = -2时从右往左删除2个v1
[v1, v1, v3, v1, v2, v1]
[v1, v1, v3, v2]
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