Redis的Java客户端的使用

Redis 的 Java 客户端使用

C++ 追求极致的性能, 而 Java没有这样的追求.

Redis 在官网公开了所使用的应用层协议 (RESP). 任何一个第三方都可以通过这个协议, 来实现出一个和 Redis 服务器通信的客户端程序.

已经有很多大佬, 做好了库, 可以让我们直接调用 (不必关注 RESP 协议的细节). 在java 生态中, 封装了 RESP 协议的 Redis 客户端是很多的. 咱们此处使用的是 jedis (jedis 提供的 api 和 redis 命令高度一致). jedis 也可以通过 maven 来下载安装.

我们这里选择 jedis 4.4.2 版本.

我们的电脑是无法直接连到云服务器的6379端口上的, 但是我们可以通过 配置 SSH 来实现在本机就能访问云服务器的6379端口.

云服务器 6379 端口 — 映射— 本机 8888 端口

1. Java 客户端连接到 Redis 服务器

关键代码:

JedisPool jedisPool = new JedisPool("url");
Jedis jedis = jedisPool.getResource()

示例:

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;public class Main {public static void main(String[] args) {// 连接到Redis服务器上JedisPool jedisPool = new JedisPool("tcp://127.0.0.1:8888");try (Jedis jedis = jedisPool.getResource()) {// Redis的各种命令, 就对应到Jedis对象的各种方法String p = jedis.ping();System.out.println(p);}}
}

2. Java 客户端使用通用命令

2.1 get 和 set 方法

import redis.clients.jedis.Jedis;
import redis.clients.jedis.params.SetParams;public class RedisDemo1 {public static void test1(Jedis jedis) {System.out.println("get 和 set 的使用");// 先清空数据库，要避免上一组测试的残留数据影响到下一组测试的结果jedis.flushAll();// 使用set方法jedis.set("key", "111");jedis.set("key2", "222");SetParams params = new SetParams(); //设置参数params.ex(10);//params.nx(); //不存在才能创建params.xx(); //存在才能修改jedis.set("key", "333", params);String value = jedis.get("key");System.out.println("value=" + value);}
}

• 运行结果:

2.2 exists 和 del 方法

import redis.clients.jedis.Jedis;public class RedisDemo2 {public static void test2(Jedis jedis) {System.out.println("exists 和 del");jedis.flushAll();jedis.set("key", "111");jedis.set("key2", "222");jedis.set("key3", "333");boolean result1 = jedis.exists("key");System.out.println("result1: " + result1);long result2 = jedis.del("key");System.out.println("result2: " + result2);boolean result3 = jedis.exists("key");System.out.println("result3: " + result3);long result4 = jedis.del("key", "key2", "key3");System.out.println("result4: " + result4);}
}

• 运行结果:

2.3 keys 方法

import redis.clients.jedis.Jedis;import java.util.Set;public class RedisDemo3 {public static void test3(Jedis jedis) {System.out.println("keys");jedis.flushAll();jedis.set("key1", "111");jedis.set("key2", "222");jedis.set("key3", "333");jedis.set("key4", "444");// redis 中的 key 不能重复，而且也是不在意顺序的Set<String> keys = jedis.keys("*"); //获取所有的keySystem.out.println(keys);}
}

• 运行结果:

2.4 expire, ttl 方法

import redis.clients.jedis.Jedis;public class RedisDemo4 {public static void test4(Jedis jedis) {System.out.println("expire 和 ttl");jedis.flushAll();jedis.set("key", "111");jedis.expire("key", 10);long time1 = jedis.ttl("key");System.out.println("time1: " + time1); //10stry {Thread.sleep(3000);} catch (InterruptedException e) {e.printStackTrace();}long time2 = jedis.ttl("key");System.out.println("time2: " + time2); //7s}
}

• 运行结果:

2.5 type 方法

package com.wang;import redis.clients.jedis.Jedis;public class RedisDemo5 {public static void test5(Jedis jedis) {System.out.println("type");jedis.flushAll();jedis.set("key1", "111");String type = jedis.type("key1");System.out.println("type1: " + type);jedis.lpush("key2", "111", "222", "333");type = jedis.type("key2");System.out.println("type2: " + type);jedis.hset("key3", "f1", "111");type = jedis.type("key3");System.out.println("type3: " + type);jedis.sadd("key4", "111", "222", "333");type = jedis.type("key4");System.out.println("type4: " + type);jedis.zadd("key5", 10, "zhangsan");type = jedis.type("key5");System.out.println("type5: " + type);}
}

• 运行结果:

3. Java 客户端使用 string 命令

3.1 mset 和 mget

import redis.clients.jedis.Jedis;import java.util.List;public class RedisDemoString1 {public static void test1(Jedis jedis) {System.out.println("mget 和 mset");jedis.flushAll();//mset: 一次设置多个key.jedis.mset("key1", "111", "key2", "222", "key3", "333");//mget: 一次获取多个key.List<String> values = jedis.mget("key1", "key2", "key100", "key3");System.out.println("values: " + values);}
}

• 运行结果:

3.2 getrange 和 setrange

import redis.clients.jedis.Jedis;public class RedisDemoString2 {public static void test2(Jedis jedis) {System.out.println("getrange 和 setrange");jedis.flushAll();jedis.set("key", "abcdefghijk");// 得到指定范围的子字符串String result = jedis.getrange("key", 2, 5);System.out.println("result: " + result);// 修改字符串jedis.setrange("key", 2, "xyz");String value = jedis.get("key");System.out.println("value: " + value);}
}

• 运行结果:

3.3 append

import redis.clients.jedis.Jedis;public class RedisDemoString3 {public static void test3(Jedis jedis) {System.out.println("append");jedis.flushAll();jedis.set("key", "abcdef");System.out.println("value1: " + jedis.get("key"));jedis.append("key", "ghij");System.out.println("value2: " +  jedis.get("key"));}
}

• 运行结果:

3.4 incr 和 decr

import redis.clients.jedis.Jedis;public class RedisDemoString4 {public static void test4(Jedis jedis) {System.out.println("incr 和 decr");jedis.flushAll();jedis.set("key", "100");long result1 = jedis.incr("key");System.out.println("result1: " + result1);System.out.println("value1: " + jedis.get("key"));long result2 = jedis.decr("key");System.out.println("result2: " + result2);System.out.println("value2: " + jedis.get("key"));}
}

• 运行结果:

4. Java 客户端使用 list 命令

4.1 lpush 和 lrange

import redis.clients.jedis.Jedis;import java.util.List;public class RedisDemoList1 {public static void test1(Jedis jedis) {System.out.println("lpush 和 lrange");jedis.flushAll();jedis.lpush("key", "111", "222", "333");List<String> result = jedis.lrange("key", 0, -1);System.out.println(result);}}

• 运行结果:

4.2 rpush

import redis.clients.jedis.Jedis;import java.util.List;public class RedisDemoList2 {public static void test2(Jedis jedis) {System.out.println("rpush");jedis.flushAll();jedis.rpush("key", "111", "222", "333");List<String> result = jedis.lrange("key", 0, -1);System.out.println("result: " + result);}}

• 运行结果:

4.3 lpop 和 rpop

import redis.clients.jedis.Jedis;public class RedisDemoList3 {public static void test3(Jedis jedis) {System.out.println("lpop");jedis.flushAll();jedis.rpush("key", "111", "222", "333");String result = jedis.lpop("key");System.out.println("result: " + result);result = jedis.lpop("key");System.out.println("result: " + result);result = jedis.lpop("key");System.out.println("result: " + result);result = jedis.lpop("key");System.out.println("result: " + result);}
}

• 运行结果:

• rpop:

import redis.clients.jedis.Jedis;public class RedisDemoList4 {public static void test4(Jedis jedis) {System.out.println("rpop");jedis.flushAll();jedis.rpush("key", "111", "222", "333");String result = jedis.rpop("key");System.out.println("result: " + result);result = jedis.rpop("key");System.out.println("result: " + result);result = jedis.rpop("key");System.out.println("result: " + result);result = jedis.rpop("key");System.out.println("result: " + result);}
}

• 运行结果:

4.4 blpop

blpop 在当 key 中有元素时, 作用和 lpop 完全相同. 当 key 中没有元素时, blpop 会阻塞, 直到 key 中有元素添加进来, 停止阻塞.

import redis.clients.jedis.Jedis;import java.util.List;public class RedisDemoList5 {public static void test5(Jedis jedis) {System.out.println("blpop");jedis.flushAll();// 返回结果是一个 "二元组"，一个表示从哪个 key 对应的list中删除的，一个表示删除的元素是什么.List<String> results = jedis.blpop(100, "key"); //设置超时时间为100sSystem.out.println("results[0]: " + results.get(0));System.out.println("results[1]: " + results.get(1));}
}

在 key 中添加元素222之后:

4.5 llen

import redis.clients.jedis.Jedis;public class RedisDemoList6 {public static void test6(Jedis jedis) {System.out.println("llen");jedis.flushAll();jedis.rpush("key", "111", "222", "333");long length = jedis.llen("key");System.out.println("列表长度: " + length);}
}

• 运行结果:

5. Java 客户端使用 set 命令

5.1 sadd 和 smembers

sadd: 往 set 中添加元素

smembers: 返回 set 中所有的元素.

    public static void test1(Jedis jedis) {System.out.println("sadd 和 smembers");jedis.flushAll();jedis.sadd("key", "111", "222", "333");Set<String> result = jedis.smembers("key");System.out.println("result: " + result);}

• 运行结果:

5.2 sismember

用于判断指定元素是否存在于集合中

    public static void test2(Jedis jedis) {System.out.println("sismember");jedis.flushAll();jedis.sadd("key", "111", "222", "333");boolean result = jedis.sismember("key", "100");// 判断100是不是key中的元素System.out.println("result: " + result);}

• 运行结果:

5.3 scard

判断 set 中的元素个数

    public static void test3(Jedis jedis) {System.out.println("scard");jedis.flushAll();jedis.sadd("key", "111", "222", "333");long result = jedis.scard("key");System.out.println("result: " + result);}

运行结果:

5.4 spop

随机删除 set 中的元素.

    public static void test4(Jedis jedis) {System.out.println("spop");jedis.flushAll();jedis.sadd("key", "111", "222", "333", "444", "555");String result = jedis.spop("key");System.out.println("result: " + result);}

• 运行结果:

5.5 sinter 和 sinterstore

sinter:

    public static void test5(Jedis jedis) {System.out.println("sinter");jedis.flushAll();jedis.sadd("key1", "111", "222", "333");jedis.sadd("key2", "111", "222", "444");Set<String> result = jedis.sinter("key1", "key2");System.out.println("result: " + result);}

• 运行结果:

sinterstore:

    public static void test6(Jedis jedis) {System.out.println("sinterstore");jedis.flushAll();jedis.sadd("key1", "111", "222", "333");jedis.sadd("key2", "111", "222", "444");long len = jedis.sinterstore("key3", "key1", "key2");System.out.println("len: " + len);Set<String> result = jedis.smembers("key3");System.out.println("result: " + result);}

• 运行结果:

6. Java 客户端使用 hash 命令

6.1 hset 和 hget

    public static void test1(Jedis jedis) {System.out.println("hset 和 hget");jedis.flushAll();jedis.hset("key", "f1", "111");Map<String, String> fields = new HashMap<>();fields.put("f2", "222");fields.put("f3", "333");jedis.hset("key", fields);System.out.println("result1: " + jedis.hget("key", "f1"));System.out.println("result2: " + jedis.hget("key", "f2"));System.out.println("result3: " + jedis.hget("key", "f100"));}

• 运行结果:

6.2 hexists 和 hdel

hexists:

    public static void test2(Jedis jedis) {System.out.println("hexists");jedis.flushAll();jedis.hset("key", "f1", "111");jedis.hset("key", "f2", "222");jedis.hset("key", "f3", "333");boolean result1 = jedis.hexists("key", "f1");System.out.println("result: " + result1);boolean result2 = jedis.hexists("key", "f100");System.out.println("result: " + result2);}

• 运行结果:

hdel:

    public static void test3(Jedis jedis) {System.out.println("hdel");jedis.flushAll();jedis.hset("key", "f1", "111");jedis.hset("key", "f2", "222");jedis.hset("key", "f3", "333");long result = jedis.hdel("key", "f1", "f2");System.out.println("result: " + result);System.out.println("f1.exists: " + jedis.hexists("key", "f1"));System.out.println("f2.exists: " + jedis.hexists("key", "f2"));}

• 运行结果:

6.3 hkeys 和 hvalues

hkeys: 获取指定 key 中的所有 field.

hvalues: 获取指定 key 中的所有 value.

    public static void test4(Jedis jedis) {System.out.println("hkeys 和 hvals");jedis.flushAll();jedis.hset("key", "f1", "111");jedis.hset("key", "f2", "222");jedis.hset("key", "f3", "333");Set<String> fields = jedis.hkeys("key");List<String> vals = jedis.hvals("key");System.out.println("fields: " + fields);System.out.println("vals: " + vals);}

• 运行结果:

6.4 hmset 和 hmget

hmset: 一次设置多组 field-value.

hmget: 一次获取多组 field-value.

    public static void test5(Jedis jedis) {System.out.println("hmset 和 hmget");jedis.flushAll();Map<String, String> map = new HashMap<>();map.put("f1", "111");map.put("f2", "222");map.put("f3", "333");jedis.hmset("key", map);List<String> values = jedis.hmget("key", "f2", "f1", "f3");System.out.println("values: " + values);}

• 运行结果:

7. Java 客户端使用 zset 命令

• zset 中 存储的元素是 element-score 类型的.

7.1 zadd 和 zrange

    public static void test1(Jedis jedis) {System.out.println("zadd 和 zrange");jedis.flushAll();jedis.zadd("key", 10, "zhangsan");Map<String, Double> map = new HashMap<>();map.put("lisi", 20.0);map.put("wangwu", 30.0);jedis.zadd("key", map);List<String> members = jedis.zrange("key", 0, -1);System.out.println("members: " + members);List<Tuple> membersWithScore = jedis.zrangeWithScores("key", 0, -1);System.out.println("membersWithScore: " + membersWithScore);String member = membersWithScore.get(0).getElement();double score = membersWithScore.get(0).getScore();System.out.println("member: " + member + ", score: " + score);}

• 运行结果:

7.2 zcard

    public static void test2(Jedis jedis) {System.out.println("zcard");jedis.flushAll();jedis.zadd("key", 10, "zhangsan");jedis.zadd("key", 20, "lisi");jedis.zadd("key", 30, "wangwu");System.out.println("len: " + jedis.zcard("key"));}

• 运行结果:

7.3 zrem

    public static void test3(Jedis jedis) {System.out.println("zrem");jedis.flushAll();jedis.zadd("key", 10, "zhangsan");jedis.zadd("key", 20, "lisi");jedis.zadd("key", 30, "wangwu");long n = jedis.zrem("key", "zhangsan");System.out.println("n: " + n);List<Tuple> result = jedis.zrangeWithScores("key", 0, -1);System.out.println("result: " + result);}

• 运行结果:

7.4 zscore

    public static void test4(Jedis jedis) {System.out.println("zscore");jedis.flushAll();jedis.zadd("key", 10, "zhangsan");jedis.zadd("key", 20, "lisi");jedis.zadd("key", 30, "wangwu");Double score = jedis.zscore("key", "zhangsan");System.out.println("zhangsan.score: " + score);}

• 运行结果:

7.5 zrank

    public static void test5(Jedis jedis) {System.out.println("zrank");jedis.flushAll();jedis.zadd("key", 10, "zhangsan");jedis.zadd("key", 20, "lisi");jedis.zadd("key", 30, "wangwu");Long rank = jedis.zrank("key", "zhangsan");System.out.println("rank: " + rank);}

• 运行结果:

8. 小结

本质上来说, Jedis 库就是对 Redis 所有命令的一个简单封装, 这里不再过多介绍. 如果有其他问题, 我们可以查看 Jedis 的官方文档 (在 github 上).