Redis之list类型

Redis之list类型

1. 列表添加/弹出元素

• 向列表左边添加元素：LPUSH key value [value …]
• 向列表右边添加元素：RPUSH key value [value…]
• 从列表左边弹出元素：LPOP key
• 从列表右边弹出元素：RPOP key

127.0.0.1:6379> lpush books C
(integer) 1
127.0.0.1:6379> lpush books C++ JAVA
(integer) 3
127.0.0.1:6379> lrange books 0 -1
1) "JAVA"
2) "C++"
3) "C"
127.0.0.1:6379> rpush books Python Golang
(integer) 5
127.0.0.1:6379> lrange books 0 -1
1) "JAVA"
2) "C++"
3) "C"
4) "Python"
5) "Golang"
127.0.0.1:6379> rpop books
"Golang"
127.0.0.1:6379> lrange books 0 -1
1) "JAVA"
2) "C++"
3) "C"
4) "Python"
127.0.0.1:6379> lpop books
"JAVA"
127.0.0.1:6379> lrange books 0 -1
1) "C++"
2) "C"
3) "Python"

2. 查看列表

LRANGE key start end
end为负数时候，-1是倒数第一个，-2是倒数第二个...

127.0.0.1:6379> lrange books 0 -1
1) "C++"
2) "C"
3) "Python"
127.0.0.1:6379> lrange books 0 -2
1) "C++"
2) "C"
127.0.0.1:6379> lrange books 0 1
1) "C++"
2) "C"
127.0.0.1:6379> lrange books 0 2
1) "C++"
2) "C"
3) "Python"
127.0.0.1:6379> lrange books 0 3
1) "C++"
2) "C"
3) "Python"

3. 获取列表中元素的个数

LLEN key

127.0.0.1:6379> lrange books 0 -1
1) "C++"
2) "C"
3) "Python"
127.0.0.1:6379> llen books
(integer) 3

4. 删除列表中指定的值

LREM key count value

• count > 0 : 从表头开始向表尾搜索，移除与 VALUE 相等的元素，数量为 COUNT 。
• count < 0 : 从表尾开始向表头搜索，移除与 VALUE 相等的元素，数量为 COUNT 的绝对值。
• count = 0 : 移除表中所有与 VALUE 相等的值。

127.0.0.1:6379> lrange books 0 -1
1) "C++"
2) "C"
3) "Python"
127.0.0.1:6379> rpush books Java C C Python
(integer) 7
127.0.0.1:6379> lrange books 0 -1
1) "C++"
2) "C"
3) "Python"
4) "Java"
5) "C"
6) "C"
7) "Python"
127.0.0.1:6379> lrem books 2 C
(integer) 2
127.0.0.1:6379> lrange books 0 -1
1) "C++"
2) "Python"
3) "Java"
4) "C"
5) "Python"
127.0.0.1:6379> lrem books 0 Python
(integer) 2
127.0.0.1:6379> lrange books 0 -1
1) "C++"
2) "Java"
3) "C"
127.0.0.1:6379> lpush books Java
(integer) 4
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "C++"
3) "Java"
4) "C"
127.0.0.1:6379> lrem books -1 Java
(integer) 1
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "C++"
3) "C"

5. 获取/指定元素的值

获取索引元素的值：LINDEX key index
指定索引元素的值：LSET key index value

127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "C++"
3) "C"
127.0.0.1:6379> lindex books 0
"Java"
127.0.0.1:6379> lindex books 1
"C++"
127.0.0.1:6379> lset books 1 Python
OK
127.0.0.1:6379> lindex books 1
"Python"
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
3) "C"

6. 向列表中插入元素

LINSERT key BEFORE|AFTER pivot value

127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
3) "C"
127.0.0.1:6379> linsert books before C Golang
(integer) 4
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
3) "Golang"
4) "C"
127.0.0.1:6379> linsert books after C Java
(integer) 5
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
3) "Golang"
4) "C"
5) "Java"

7. 删除指定索引范围之外的所有元素

LTRIM key start end

127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
3) "Golang"
4) "C"
5) "Java"
127.0.0.1:6379> ltrim books 0 -2
OK
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
3) "Golang"
4) "C"

8. 将元素从一个列表转移到另一个列表

RPOPLPUSH source destination

127.0.0.1:6379> rpoplpush books language
"C"
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
3) "Golang"
127.0.0.1:6379> lrange language 0 -1
1) "C"
127.0.0.1:6379> rpoplpush books language
"Golang"
127.0.0.1:6379> lrange books 0 -1
1) "Java"
2) "Python"
127.0.0.1:6379> lrange language 0 -1
1) "Golang"
2) "C"

9. 应用场景

9.1 队列

使用LPUSH+RPOP或者RPOP+LPUSH可以模拟队列操作，具体请参考我之前博客

9.2 类似微信上订阅公众号（或者喜欢的文章）

看到喜欢的文章，对该订阅号点个关注，把该公众号主键放到list中去，然后点开订阅号，可以看到自己关注的所有的订阅号，也可以让一次显示10条。

具体的redis操作：

127.0.0.1:6379> lpush gzdyh:user1001 dyh1
(integer) 1
127.0.0.1:6379> lpush gzdyh:user1001 dyh2 dyh3
(integer) 3
127.0.0.1:6379> lrange gzdyh:user1001 0 -1
1) "dyh3"
2) "dyh2"
3) "dyh1"
127.0.0.1:6379> lrange gzdyh:user1001 0 10
1) "dyh3"
2) "dyh2"
3) "dyh1"