Redis 字符串

Redis 字符串简介

Redis 字符串存储字节序列，包括文本、序列化对象和二进制数组。因此，字符串是您可以与 Redis 键关联的最简单的值类型。它们通常用于缓存，但它们支持额外的功能，可以让您实现计数器并执行按位操作。

由于 Redis 键是字符串，当我们将字符串类型也用作值时，我们实际上是在将字符串映射到另一个字符串。字符串数据类型对于许多用例非常有用，例如缓存 HTML 片段或页面。

>_ Redis CLI

    > SET bike:1 Deimos
    OK
    > GET bike:1
    "Deimos"

Python

"""
Code samples for String doc pages:
    https://redis.ac.cn/docs/latest/develop/data-types/strings/
"""

import redis

r = redis.Redis(decode_responses=True)

res1 = r.set("bike:1", "Deimos")
print(res1)  # True
res2 = r.get("bike:1")
print(res2)  # Deimos


res3 = r.set("bike:1", "bike", nx=True)
print(res3)  # None
print(r.get("bike:1"))  # Deimos
res4 = r.set("bike:1", "bike", xx=True)
print(res4)  # True


res5 = r.mset({"bike:1": "Deimos", "bike:2": "Ares", "bike:3": "Vanth"})
print(res5)  # True
res6 = r.mget(["bike:1", "bike:2", "bike:3"])
print(res6)  # ['Deimos', 'Ares', 'Vanth']


r.set("total_crashes", 0)
res7 = r.incr("total_crashes")
print(res7)  # 1
res8 = r.incrby("total_crashes", 10)
print(res8)  # 11

Node.js

import assert from 'assert';
import { createClient } from 'redis';

const client = await createClient();
await client.connect();

const res1 = await client.set("bike:1", "Deimos");
console.log(res1);  // OK
const res2 = await client.get("bike:1");
console.log(res2);  // Deimos


const res3 = await client.set("bike:1", "bike", {'NX': true});
console.log(res3);  // null
console.log(await client.get("bike:1"));  // Deimos
const res4 = await client.set("bike:1", "bike", {'XX': true});
console.log(res4);  // OK


const res5 = await client.mSet([
  ["bike:1", "Deimos"],
  ["bike:2", "Ares"],
  ["bike:3", "Vanth"]
]);

console.log(res5);  // OK
const res6 = await client.mGet(["bike:1", "bike:2", "bike:3"]);
console.log(res6);  // ['Deimos', 'Ares', 'Vanth']


await client.set("total_crashes", 0);
const res7 = await client.incr("total_crashes");
console.log(res7); // 1
const res8 = await client.incrBy("total_crashes", 10);
console.log(res8); // 11

Java

package io.redis.examples;


import redis.clients.jedis.UnifiedJedis;
import redis.clients.jedis.params.SetParams;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class StringExample {
  public void run() {
    try (UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379")) {

      String res1 = jedis.set("bike:1", "Deimos");
      System.out.println(res1); // OK
      String res2 = jedis.get("bike:1");
      System.out.println(res2); // Deimos


      Long res3 = jedis.setnx("bike:1", "bike");
      System.out.println(res3); // 0 (because key already exists)
      System.out.println(jedis.get("bike:1")); // Deimos (value is unchanged)
      String res4 = jedis.set("bike:1", "bike", SetParams.setParams().xx()); // set the value to "bike" if it
      // already
      // exists
      System.out.println(res4); // OK


      String res5 = jedis.mset("bike:1", "Deimos", "bike:2", "Ares", "bike:3", "Vanth");
      System.out.println(res5); // OK
      List<String> res6 = jedis.mget("bike:1", "bike:2", "bike:3");
      System.out.println(res6); // [Deimos, Ares, Vanth]


      jedis.set("total_crashes", "0");
      Long res7 = jedis.incr("total_crashes");
      System.out.println(res7); // 1
      Long res8 = jedis.incrBy("total_crashes", 10);
      System.out.println(res8); // 11

    }
  }
}


public class StringSnippets
{
    public void run()
    {
        var redis = ConnectionMultiplexer.Connect("localhost:6379");
        var db = redis.GetDatabase();



        var res1 = db.StringSet("bike:1", "Deimos");
        Console.WriteLine(res1); // true
        var res2 = db.StringGet("bike:1");
        Console.WriteLine(res2); // Deimos


        var res3 = db.StringSet("bike:1", "bike", when: When.NotExists);
        Console.WriteLine(res3); // false
        Console.WriteLine(db.StringGet("bike:1"));
        var res4 = db.StringSet("bike:1", "bike", when: When.Exists);
        Console.WriteLine(res4); // true


        var res5 = db.StringSet(new KeyValuePair<RedisKey, RedisValue>[]
        {
            new ("bike:1", "Deimos"), new("bike:2", "Ares"), new("bike:3", "Vanth")
        });
        Console.WriteLine(res5);
        var res6 = db.StringGet(new RedisKey[] { "bike:1", "bike:2", "bike:3" });
        Console.WriteLine(res6);


        db.StringSet("total_crashes", 0);
        var res7 = db.StringIncrement("total_crashes");
        Console.WriteLine(res7); // 1
        var res8 = db.StringIncrement("total_crashes", 10);
        Console.WriteLine(res8);

    }
}

如您所见，使用 SET 和 GET 命令是我们设置和检索字符串值的方式。请注意，SET 会替换已存储在键中的任何现有值，如果键已存在，即使该键与非字符串值相关联。因此，SET 执行赋值操作。

值可以是各种类型的字符串（包括二进制数据），例如，您可以将 jpeg 图像存储在值中。值的大小不能超过 512 MB。

SET 命令有一些有趣的选项，以附加参数的形式提供。例如，我可以要求 SET 在键已存在时失败，或者相反，只有在键已存在时才成功。

>_ Redis CLI

    > set bike:1 bike nx
    (nil)
    > set bike:1 bike xx
    OK

Python

"""
Code samples for String doc pages:
    https://redis.ac.cn/docs/latest/develop/data-types/strings/
"""

import redis

r = redis.Redis(decode_responses=True)

res1 = r.set("bike:1", "Deimos")
print(res1)  # True
res2 = r.get("bike:1")
print(res2)  # Deimos


res3 = r.set("bike:1", "bike", nx=True)
print(res3)  # None
print(r.get("bike:1"))  # Deimos
res4 = r.set("bike:1", "bike", xx=True)
print(res4)  # True


res5 = r.mset({"bike:1": "Deimos", "bike:2": "Ares", "bike:3": "Vanth"})
print(res5)  # True
res6 = r.mget(["bike:1", "bike:2", "bike:3"])
print(res6)  # ['Deimos', 'Ares', 'Vanth']


r.set("total_crashes", 0)
res7 = r.incr("total_crashes")
print(res7)  # 1
res8 = r.incrby("total_crashes", 10)
print(res8)  # 11

Node.js

import assert from 'assert';
import { createClient } from 'redis';

const client = await createClient();
await client.connect();

const res1 = await client.set("bike:1", "Deimos");
console.log(res1);  // OK
const res2 = await client.get("bike:1");
console.log(res2);  // Deimos


const res3 = await client.set("bike:1", "bike", {'NX': true});
console.log(res3);  // null
console.log(await client.get("bike:1"));  // Deimos
const res4 = await client.set("bike:1", "bike", {'XX': true});
console.log(res4);  // OK


const res5 = await client.mSet([
  ["bike:1", "Deimos"],
  ["bike:2", "Ares"],
  ["bike:3", "Vanth"]
]);

console.log(res5);  // OK
const res6 = await client.mGet(["bike:1", "bike:2", "bike:3"]);
console.log(res6);  // ['Deimos', 'Ares', 'Vanth']


await client.set("total_crashes", 0);
const res7 = await client.incr("total_crashes");
console.log(res7); // 1
const res8 = await client.incrBy("total_crashes", 10);
console.log(res8); // 11

Java

package io.redis.examples;


import redis.clients.jedis.UnifiedJedis;
import redis.clients.jedis.params.SetParams;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class StringExample {
  public void run() {
    try (UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379")) {

      String res1 = jedis.set("bike:1", "Deimos");
      System.out.println(res1); // OK
      String res2 = jedis.get("bike:1");
      System.out.println(res2); // Deimos


      Long res3 = jedis.setnx("bike:1", "bike");
      System.out.println(res3); // 0 (because key already exists)
      System.out.println(jedis.get("bike:1")); // Deimos (value is unchanged)
      String res4 = jedis.set("bike:1", "bike", SetParams.setParams().xx()); // set the value to "bike" if it
      // already
      // exists
      System.out.println(res4); // OK


      String res5 = jedis.mset("bike:1", "Deimos", "bike:2", "Ares", "bike:3", "Vanth");
      System.out.println(res5); // OK
      List<String> res6 = jedis.mget("bike:1", "bike:2", "bike:3");
      System.out.println(res6); // [Deimos, Ares, Vanth]


      jedis.set("total_crashes", "0");
      Long res7 = jedis.incr("total_crashes");
      System.out.println(res7); // 1
      Long res8 = jedis.incrBy("total_crashes", 10);
      System.out.println(res8); // 11

    }
  }
}


public class StringSnippets
{
    public void run()
    {
        var redis = ConnectionMultiplexer.Connect("localhost:6379");
        var db = redis.GetDatabase();



        var res1 = db.StringSet("bike:1", "Deimos");
        Console.WriteLine(res1); // true
        var res2 = db.StringGet("bike:1");
        Console.WriteLine(res2); // Deimos


        var res3 = db.StringSet("bike:1", "bike", when: When.NotExists);
        Console.WriteLine(res3); // false
        Console.WriteLine(db.StringGet("bike:1"));
        var res4 = db.StringSet("bike:1", "bike", when: When.Exists);
        Console.WriteLine(res4); // true


        var res5 = db.StringSet(new KeyValuePair<RedisKey, RedisValue>[]
        {
            new ("bike:1", "Deimos"), new("bike:2", "Ares"), new("bike:3", "Vanth")
        });
        Console.WriteLine(res5);
        var res6 = db.StringGet(new RedisKey[] { "bike:1", "bike:2", "bike:3" });
        Console.WriteLine(res6);


        db.StringSet("total_crashes", 0);
        var res7 = db.StringIncrement("total_crashes");
        Console.WriteLine(res7); // 1
        var res8 = db.StringIncrement("total_crashes", 10);
        Console.WriteLine(res8);

    }
}

除了操作字符串的命令外，还有很多其他命令。例如，GETSET 命令将键设置为新值，并返回旧值作为结果。您可以使用此命令，例如，如果您有一个系统使用 INCR 在您的网站每次收到新访问者时递增 Redis 键。您可能希望每小时收集一次此信息，而不会丢失任何递增。您可以 GETSET 该键，将它分配给新值“0”并读取旧值。

能够在单个命令中设置或检索多个键的值对于减少延迟也很有用。因此，存在 MSET 和 MGET 命令。

>_ Redis CLI

    > mset bike:1 "Deimos" bike:2 "Ares" bike:3 "Vanth"
    OK
    > mget bike:1 bike:2 bike:3
    1) "Deimos"
    2) "Ares"
    3) "Vanth"

Python

"""
Code samples for String doc pages:
    https://redis.ac.cn/docs/latest/develop/data-types/strings/
"""

import redis

r = redis.Redis(decode_responses=True)

res1 = r.set("bike:1", "Deimos")
print(res1)  # True
res2 = r.get("bike:1")
print(res2)  # Deimos


res3 = r.set("bike:1", "bike", nx=True)
print(res3)  # None
print(r.get("bike:1"))  # Deimos
res4 = r.set("bike:1", "bike", xx=True)
print(res4)  # True


res5 = r.mset({"bike:1": "Deimos", "bike:2": "Ares", "bike:3": "Vanth"})
print(res5)  # True
res6 = r.mget(["bike:1", "bike:2", "bike:3"])
print(res6)  # ['Deimos', 'Ares', 'Vanth']


r.set("total_crashes", 0)
res7 = r.incr("total_crashes")
print(res7)  # 1
res8 = r.incrby("total_crashes", 10)
print(res8)  # 11

Node.js

import assert from 'assert';
import { createClient } from 'redis';

const client = await createClient();
await client.connect();

const res1 = await client.set("bike:1", "Deimos");
console.log(res1);  // OK
const res2 = await client.get("bike:1");
console.log(res2);  // Deimos


const res3 = await client.set("bike:1", "bike", {'NX': true});
console.log(res3);  // null
console.log(await client.get("bike:1"));  // Deimos
const res4 = await client.set("bike:1", "bike", {'XX': true});
console.log(res4);  // OK


const res5 = await client.mSet([
  ["bike:1", "Deimos"],
  ["bike:2", "Ares"],
  ["bike:3", "Vanth"]
]);

console.log(res5);  // OK
const res6 = await client.mGet(["bike:1", "bike:2", "bike:3"]);
console.log(res6);  // ['Deimos', 'Ares', 'Vanth']


await client.set("total_crashes", 0);
const res7 = await client.incr("total_crashes");
console.log(res7); // 1
const res8 = await client.incrBy("total_crashes", 10);
console.log(res8); // 11

Java

package io.redis.examples;


import redis.clients.jedis.UnifiedJedis;
import redis.clients.jedis.params.SetParams;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class StringExample {
  public void run() {
    try (UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379")) {

      String res1 = jedis.set("bike:1", "Deimos");
      System.out.println(res1); // OK
      String res2 = jedis.get("bike:1");
      System.out.println(res2); // Deimos


      Long res3 = jedis.setnx("bike:1", "bike");
      System.out.println(res3); // 0 (because key already exists)
      System.out.println(jedis.get("bike:1")); // Deimos (value is unchanged)
      String res4 = jedis.set("bike:1", "bike", SetParams.setParams().xx()); // set the value to "bike" if it
      // already
      // exists
      System.out.println(res4); // OK


      String res5 = jedis.mset("bike:1", "Deimos", "bike:2", "Ares", "bike:3", "Vanth");
      System.out.println(res5); // OK
      List<String> res6 = jedis.mget("bike:1", "bike:2", "bike:3");
      System.out.println(res6); // [Deimos, Ares, Vanth]


      jedis.set("total_crashes", "0");
      Long res7 = jedis.incr("total_crashes");
      System.out.println(res7); // 1
      Long res8 = jedis.incrBy("total_crashes", 10);
      System.out.println(res8); // 11

    }
  }
}


public class StringSnippets
{
    public void run()
    {
        var redis = ConnectionMultiplexer.Connect("localhost:6379");
        var db = redis.GetDatabase();



        var res1 = db.StringSet("bike:1", "Deimos");
        Console.WriteLine(res1); // true
        var res2 = db.StringGet("bike:1");
        Console.WriteLine(res2); // Deimos


        var res3 = db.StringSet("bike:1", "bike", when: When.NotExists);
        Console.WriteLine(res3); // false
        Console.WriteLine(db.StringGet("bike:1"));
        var res4 = db.StringSet("bike:1", "bike", when: When.Exists);
        Console.WriteLine(res4); // true


        var res5 = db.StringSet(new KeyValuePair<RedisKey, RedisValue>[]
        {
            new ("bike:1", "Deimos"), new("bike:2", "Ares"), new("bike:3", "Vanth")
        });
        Console.WriteLine(res5);
        var res6 = db.StringGet(new RedisKey[] { "bike:1", "bike:2", "bike:3" });
        Console.WriteLine(res6);


        db.StringSet("total_crashes", 0);
        var res7 = db.StringIncrement("total_crashes");
        Console.WriteLine(res7); // 1
        var res8 = db.StringIncrement("total_crashes", 10);
        Console.WriteLine(res8);

    }
}

当使用 MGET 时，Redis 返回一个值数组。

字符串作为计数器

即使字符串是 Redis 的基本值，您也可以对它们执行一些有趣的操作。例如，其中之一是原子递增。

>_ Redis CLI

    > set total_crashes 0
    OK
    > incr total_crashes
    (integer) 1
    > incrby total_crashes 10
    (integer) 11

Python

"""
Code samples for String doc pages:
    https://redis.ac.cn/docs/latest/develop/data-types/strings/
"""

import redis

r = redis.Redis(decode_responses=True)

res1 = r.set("bike:1", "Deimos")
print(res1)  # True
res2 = r.get("bike:1")
print(res2)  # Deimos


res3 = r.set("bike:1", "bike", nx=True)
print(res3)  # None
print(r.get("bike:1"))  # Deimos
res4 = r.set("bike:1", "bike", xx=True)
print(res4)  # True


res5 = r.mset({"bike:1": "Deimos", "bike:2": "Ares", "bike:3": "Vanth"})
print(res5)  # True
res6 = r.mget(["bike:1", "bike:2", "bike:3"])
print(res6)  # ['Deimos', 'Ares', 'Vanth']


r.set("total_crashes", 0)
res7 = r.incr("total_crashes")
print(res7)  # 1
res8 = r.incrby("total_crashes", 10)
print(res8)  # 11

Node.js

import assert from 'assert';
import { createClient } from 'redis';

const client = await createClient();
await client.connect();

const res1 = await client.set("bike:1", "Deimos");
console.log(res1);  // OK
const res2 = await client.get("bike:1");
console.log(res2);  // Deimos


const res3 = await client.set("bike:1", "bike", {'NX': true});
console.log(res3);  // null
console.log(await client.get("bike:1"));  // Deimos
const res4 = await client.set("bike:1", "bike", {'XX': true});
console.log(res4);  // OK


const res5 = await client.mSet([
  ["bike:1", "Deimos"],
  ["bike:2", "Ares"],
  ["bike:3", "Vanth"]
]);

console.log(res5);  // OK
const res6 = await client.mGet(["bike:1", "bike:2", "bike:3"]);
console.log(res6);  // ['Deimos', 'Ares', 'Vanth']


await client.set("total_crashes", 0);
const res7 = await client.incr("total_crashes");
console.log(res7); // 1
const res8 = await client.incrBy("total_crashes", 10);
console.log(res8); // 11

Java

package io.redis.examples;


import redis.clients.jedis.UnifiedJedis;
import redis.clients.jedis.params.SetParams;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class StringExample {
  public void run() {
    try (UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379")) {

      String res1 = jedis.set("bike:1", "Deimos");
      System.out.println(res1); // OK
      String res2 = jedis.get("bike:1");
      System.out.println(res2); // Deimos


      Long res3 = jedis.setnx("bike:1", "bike");
      System.out.println(res3); // 0 (because key already exists)
      System.out.println(jedis.get("bike:1")); // Deimos (value is unchanged)
      String res4 = jedis.set("bike:1", "bike", SetParams.setParams().xx()); // set the value to "bike" if it
      // already
      // exists
      System.out.println(res4); // OK


      String res5 = jedis.mset("bike:1", "Deimos", "bike:2", "Ares", "bike:3", "Vanth");
      System.out.println(res5); // OK
      List<String> res6 = jedis.mget("bike:1", "bike:2", "bike:3");
      System.out.println(res6); // [Deimos, Ares, Vanth]


      jedis.set("total_crashes", "0");
      Long res7 = jedis.incr("total_crashes");
      System.out.println(res7); // 1
      Long res8 = jedis.incrBy("total_crashes", 10);
      System.out.println(res8); // 11

    }
  }
}


public class StringSnippets
{
    public void run()
    {
        var redis = ConnectionMultiplexer.Connect("localhost:6379");
        var db = redis.GetDatabase();



        var res1 = db.StringSet("bike:1", "Deimos");
        Console.WriteLine(res1); // true
        var res2 = db.StringGet("bike:1");
        Console.WriteLine(res2); // Deimos


        var res3 = db.StringSet("bike:1", "bike", when: When.NotExists);
        Console.WriteLine(res3); // false
        Console.WriteLine(db.StringGet("bike:1"));
        var res4 = db.StringSet("bike:1", "bike", when: When.Exists);
        Console.WriteLine(res4); // true


        var res5 = db.StringSet(new KeyValuePair<RedisKey, RedisValue>[]
        {
            new ("bike:1", "Deimos"), new("bike:2", "Ares"), new("bike:3", "Vanth")
        });
        Console.WriteLine(res5);
        var res6 = db.StringGet(new RedisKey[] { "bike:1", "bike:2", "bike:3" });
        Console.WriteLine(res6);


        db.StringSet("total_crashes", 0);
        var res7 = db.StringIncrement("total_crashes");
        Console.WriteLine(res7); // 1
        var res8 = db.StringIncrement("total_crashes", 10);
        Console.WriteLine(res8);

    }
}

该 INCR 命令将字符串值解析为整数，将其递增 1，最后将获得的值设置为新值。还有其他类似的命令，例如 INCRBY，DECR 和 DECRBY。在内部，它始终是相同的命令，以略微不同的方式起作用。

INCR 是原子的意味着什么？即使多个客户端对同一个键发出 INCR，也不会进入竞争状态。例如，客户端 1 读取“10”，客户端 2 同时读取“10”，两者都递增到 11，并将新值设置为 11 这种情况永远不会发生。最终值始终为 12，并且读-增量-设置操作是在所有其他客户端未同时执行命令的情况下执行的。

限制

默认情况下，单个 Redis 字符串最大可以为 512 MB。

基本命令

获取和设置字符串

SET 存储字符串值。
SETNX 仅当键不存在时才存储字符串值。对于实现锁很有用。
GET 检索字符串值。
MGET 在单个操作中检索多个字符串值。

管理计数器

INCRBY 原子地递增（并在传递负数时递减）存储在给定键处的计数器。
还有另一个用于浮点数计数器的命令：INCRBYFLOAT.

按位运算

要对字符串执行按位运算，请参阅位图数据类型文档。

查看完整的字符串命令列表.

性能

大多数字符串操作都是 O(1)，这意味着它们非常高效。但是，请注意 SUBSTR、GETRANGE 和 SETRANGE 命令，它们可能是 O(n)。这些随机访问字符串命令在处理大型字符串时可能会导致性能问题。

替代方案

如果您将结构化数据存储为序列化字符串，您可能还想考虑 Redis 哈希或 JSON.

了解更多

Redis 字符串解释是关于 Redis 字符串的简短、全面的视频解释器。
Redis 大学的 RU101 详细介绍了 Redis 字符串。

产品

工具

主要功能

了解工作原理

获取 Redis

用例

行业

客户案例研究

专家服务

关于

学习

连接

向量搜索

产品

工具

主要功能

了解工作原理

获取 Redis

用例

行业

客户案例研究

专家服务

关于

学习

连接

向量搜索

Redis 字符串

字符串作为计数器

限制

基本命令

获取和设置字符串

管理计数器

按位运算

性能

替代方案

了解更多

在本页上