Redis学习笔记

1 安装

$ wget http://download.redis.io/releases/redis-3.0.7.tar.gz $ tar xzf redis-3.0.7.tar.gz
$ cd redis-3.0.7
$ make

网页下载地址：http://www.redis.cn/download.html

2 启动服务端

$ src/redis-server

3 启动客户端

You can interact with Redis using the built-in client:

$ src/redis-cli
redis> set foo bar
OK
redis> get foo
“bar”

数据类型：

类型常量	对象的名称	TYPE命令输出值
REDIS_STRING	字符串对象	“string”
REDIS_LIST	列表对象	“list”
REDIS_HASH	哈希对象	“hash”
REDIS_SET	集合对象	“set”
REDIS_ZSET	有序集合对象	“zset”

常用命令：

1 自增（原子操作）

SET connections 10
INCR connections => 11
INCR connections => 12
DEL connections
INCR connections => 1

对应的为DECR。

增加指定数字：INCRBY，对应的为DECRBY。

2 设置失效时间

SET resource:lock "Redis Demo"
EXPIRE resource:lock 120
resource:lock将在120s内被删除

获取距离失效的时间

TTL resource:lock

3 list

RPUSH puts the new value at the end of the list.

RPUSH friends "Alice"
RPUSH friends "Bob"

LPUSH puts the new value at the start of the list.

LPUSH friends “Sam”

LPOP、RPOP为移除列表的第一个/最后一个元素。

LRANGE gives a subset of the list. It takes the index of the first element you want to retrieve as its first parameter and the index of the last element you want to retrieve as its second parameter. A value of -1 for the second parameter means to retrieve elements until the end of the list.

LRANGE friends 0 -1 => 1) "Sam", 2) "Alice", 3) "Bob"
LRANGE friends 0 1 => 1) "Sam", 2) "Alice"
LRANGE friends 1 2 => 1) "Alice", 2) “Bob"

LLEN returns the current length of the list.

LLEN friends => 3

LPOP removes the first element from the list and returns it.

LPOP friends => "Sam"

RPOP removes the last element from the list and returns it.

RPOP friends => "Bob"

Note that the list now only has one element:

LLEN friends => 1
LRANGE friends 0 -1 => 1) "Alice"

4 set

SADD adds the given value to the set.

SADD superpowers "flight"
SADD superpowers "x-ray vision"
SADD superpowers "reflexes"

SREM removes the given value from the set.

SREM superpowers “reflexes"

SCARD myset => 4 (set中元素个数)
SINTER //返回两个或多个set的交集

SISMEMBER tests if the given value is in the set. It returns 1 if the value is there and 0 if it is not.

SISMEMBER superpowers "flight" => 1
SISMEMBER superpowers "reflexes" => 0

SMEMBERS returns a list of all the members of this set.

SMEMBERS superpowers => 1) "flight", 2) "x-ray vision"

SUNION combines two or more sets and returns the list of all elements.

SADD birdpowers "pecking"
SADD birdpowers "flight"
SUNION superpowers birdpowers => 1) "pecking", 2) "x-ray vision", 3) “flight”

SPOP //移除并返回列表中的一个随机元素
ZCOUNT //计算在有序集合中指定区间分数的成员数

5 zset

Sets are a very handy data type, but as they are unsorted they don’t work well for a number of problems. This is why Redis 1.2 introduced Sorted Sets.

A sorted set is similar to a regular set, but now each value has an associated score. This score is used to sort the elements in the set.

ZADD hackers 1940 "Alan Kay"
ZADD hackers 1906 "Grace Hopper"
ZADD hackers 1953 "Richard Stallman"
ZADD hackers 1965 "Yukihiro Matsumoto"
ZADD hackers 1916 "Claude Shannon"
ZADD hackers 1969 "Linus Torvalds"
ZADD hackers 1957 "Sophie Wilson"
ZADD hackers 1912 "Alan Turing"

In these examples, the scores are years of birth and the values are the names of famous hackers.

ZRANGE hackers 2 4 => 1) "Claude Shannon", 2) "Alan Kay", 3) "Richard Stallman”
ZSCORE //获取元素的score值

6 hset

Simple strings, sets and sorted sets already get a lot done but there is one more data type Redis can handle: Hashes.

Hashes are maps between string fields and string values, so they are the perfect data type to represent objects (eg: A User with a number of fields like name, surname, age, and so forth):

HSET user:1000 name "John Smith"
HSET user:1000 email "john.smith@example.com"
HSET user:1000 password "s3cret"

To get back the saved data use HGETALL:

HGETALL user:1000

You can also set multiple fields at once:

HMSET user:1001 name "Mary Jones" password "hidden" email "mjones@example.com"

If you only need a single field value that is possible as well:

HGET user:1001 name => "Mary Jones”

PUBSUB

redis是一个基于key-value的存储系统，但同样提供了许多其他的使用的组件，比如SUBSCRIBE、PUBLISH这两个命令。这两个命令能让你非常方便地再两个进程中进行通信。

订阅/发布/取消订阅

SUBSCRIBE、PUBLISH、UNSUBSCRIBE

# SUBSCRIBE 订阅给定的一个或多个频道的信息 SUBSCRIBE channel1 channel2
127.0.0.1:6379> SUBSCRIBE channel1
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "channel1"
3) (integer) 1

# PUBLISH 将信息发送到指定的频道 PUBLISH CHANNEL MESSAGE 返回值为订阅该频道的客户端数量
127.0.0.1:6379> PUBLISH channel1 message1
(integer) 1

事务

Redis事务让一组命令在单个步骤执行。事务中有两个属性，说明如下：

在一个事务中的所有命令按顺序执行作为单个隔离操作。通过另一个客户端发出的请求在Redis的事务的过程中执行，这是不可能的。

Redis的事务具有原子性。原子意味着要么所有的命令都执行或都不执行。

Redis的事务由指令多重发起，然后需要传递在事务，而且整个事务是通过执行命令EXEC执行命令列表。

redis 127.0.0.1:6379> MULTI
OK
List of commands here
redis 127.0.0.1:6379> EXEC

Java连接Redis

首先需要下载jedis.jar，将其加入类路径，或者添加maven依赖。

<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.8.1</version>
</dependency>

代码示例如下：

import redis.clients.jedis.Jedis;

import java.util.List;
import java.util.Map;

public class TestRedis {
public static void main(String[] args) {
Jedis jedis = new Jedis("localhost");
print(jedis.ping());
print();

jedis.set("name", "lee");
print(jedis.get("name"));
print();

jedis.lpush("vector", "bbb");
jedis.lpush("vector", "aaa");
jedis.rpush("vector", "ccc");
List<String> list = jedis.lrange("vector", 0, -1);
for (int i = 0; i < list.size(); i++) {
print(list.get(i));
}
print();

jedis.hset("person1", "name", "Lee");
jedis.hset("person1", "age", "12");
jedis.hset("person1", "address", "beijing");

Map<String, String> mymap = jedis.hgetAll("person1");
for (Map.Entry<String, String> entry : mymap.entrySet()) {
print(entry.getKey() + " " + entry.getValue());
}
}

public static void print(Object...objects) {
for (Object obj: objects) {
System.out.print(obj.toString() + " ");
}
System.out.println();
}
}