Redis简单介绍以及使用

Redis

一、初始redis

redies一般有做缓存，在以前我们操作数据是都是从数据库中取，但数据库中的数据是存放在磁盘中，每一次从数据库中取数据时都会涉及到IO操作比较耗时，所以引用了缓存机制

1.1 redis软件

阿里网盘地址:https://www.aliyundrive.com/s/tkuu1vKaoky

软件打开后的页面

redis-cli.exe：是redis的操作程序

redis-server.exe:是redis的客户端

redis.windows.conf ;是redis的配置文件

注意:在使用radis的时候一定要启动redis的客户端

打开客户端的命令:redis-server.exe 全路径名\redis.windows.conf

注意：要在redis安装文件的根目录下执行这个命令

看到这个页面后，就说明redis的客户端已经开启，此时就不要去动它了，直接去执行redis-cli.exe就可以输入redis的相关命令

1.2 redis的数据结构,及相关命令

1.2.1 数据结构

redis存储结构就是key:value,它的key都是字符串类型，value有5中数据类型:

字符串

list 列表类型有序重复

set集合：无序(存取顺序不一致) 不重复

hash 哈希类型

sortedset 有序集合类型 :有序，不允许重复

####1.2.2 相关命令

#####String:字符串类型

命令格式:
set key:value

**get key**

**del key**

**append key value**

**expire key time**

**setnx key value
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127.0.0.1:6379> set name lisi  //向缓存中添加数据 key: name value : list
OK
127.0.0.1:6379> get name //从缓存中取数据 get key
"lisi"
127.0.0.1:6379> set name wangwu //覆盖缓存中已经存在的数据
OK
127.0.0.1:6379> get name
"wangwu"
127.0.0.1:6379> del name//删除 
(integer) 1
127.0.0.1:6379> get name
(nil)
127.0.0.1:6379> set num 1
OK
127.0.0.1:6379> get num
"1"
127.0.0.1:6379> incr num//缓存中key 对应的value自增1
(integer) 2
127.0.0.1:6379> decr num//缓存中key 对应的value自减1
(integer) 1
127.0.0.1:6379> incrby num 3//缓存中key 对应的value自增3
(integer) 4
127.0.0.1:6379> decrby num 3//缓存中key 对应的value自减3
(integer) 1
127.0.0.1:6379> set str hello
OK
127.0.0.1:6379> append str world//向key对应的value后追加world
(integer) 10
127.0.0.1:6379> strlen str//获取key对应value的长度
(integer) 10
127.0.0.1:6379> mset age 12 address usa score 65//添加多个
OK
127.0.0.1:6379> keys *//查询所有的key
1) "itemId"
2) "age"
3) "address"
4) "json_province"
5) "num"
6) "mylist"
7) "str"
8) "user"
9) "zset"
10) "myset"
11) "score"
127.0.0.1:6379> expire name 30
(integer) 0
127.0.0.1:6379> expire age 30//设置age 的过期时间 为 30s，30s后在age在缓存中就无法获取
(integer) 1
127.0.0.1:6379> get age
"12"
127.0.0.1:6379> get age
(nil)
127.0.0.1:6379> setnx address china//判断缓存中是否有key，如果存在就无操作，否则就添加
(integer) 0
127.0.0.1:6379>
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哈希类型 hash

//命令格式
hset key field value :添加

hget key field：获取

hdel key field:删除

hgetall key：查询所有
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127.0.0.1:6379> hset myhash name lisi//添加
(integer) 1
127.0.0.1:6379> hset myhash password 123
(integer) 1
127.0.0.1:6379> hget myhash name//获取
"lisi"
127.0.0.1:6379> hget myhash password
"123"
127.0.0.1:6379> hgetall myhash//显示所有
1) "name"
2) "lisi"
3) "password"
4) "123"
127.0.0.1:6379> hdel myhash password
(integer) 1
127.0.0.1:6379> hget myhash password
(nil)
127.0.0.1:6379> hlen myhash//获取长度
(integer) 1
127.0.0.1:6379> hset user name wuwu
(integer) 1
127.0.0.1:6379> hset user age 12
(integer) 0
127.0.0.1:6379> hset user password 321
(integer) 1
127.0.0.1:6379> hgetall user
1) "username"
2) "zhangsan"
3) "age"
4) "12"
5) "address"
6) "CHN"
7) "name"
8) "wuwu"
9) "password"
10) "321"
127.0.0.1:6379> hlen user
(integer) 5
127.0.0.1:6379> hkeys user
1) "username"
2) "age"
3) "address"
4) "name"
5) "password"
127.0.0.1:6379> hvals user
1) "zhangsan"
2) "12"
3) "CHN"
4) "wuwu"
5) "321"
127.0.0.1:6379>
127.0.0.1:6379> hincrby user age 2
(integer) 14
127.0.0.1:6379> hget user age
"14"
127.0.0.1:6379>
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list 列表类型

left:左 right: 右

push 入

pop 出

这个list就好比一个队列：先进先出

lpush key value 从左边入队

lrange key start step :start 0 表示从下标0开始 -1表示步长 -1, 0 -1显示list中所有信息

lpop key 从左边出

同理

rpush

rpop

> 127.0.0.1:6379> lpush list a 
> (integer) 1
> 127.0.0.1:6379> lpush list b
> (integer) 2
> 127.0.0.1:6379> lpush list c
> (integer) 3
> 127.0.0.1:6379> lpush list d
> (integer) 4
> 127.0.0.1:6379> lrange list 0 -1
> 1) "d"
> 2) "c"
> 3) "b"
> 4) "a"
> 127.0.0.1:6379> rpush list a
> (integer) 5
> 127.0.0.1:6379> lrange list 0 -1
> 1) "d"
> 2) "c"
> 3) "b"
> 4) "a"
> 5) "a"
> 127.0.0.1:6379> lpop list
> "d"
> 127.0.0.1:6379> lrange list 0 -1
> 1) "c"
> 2) "b"
> 3) "a"
> 4) "a"
> 127.0.0.1:6379> rpop list
> "a"
> 127.0.0.1:6379> lrange list 0 -1
> 1) "c"
> 2) "b"
> 3) "a"
> 127.0.0.1:6379> lindex list 2
> "a"
> 127.0.0.1:6379> llen list
> (integer) 3
> 127.0.0.1:6379> lrem list 1 b
> (integer) 1
> 127.0.0.1:6379>


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set 集合不重复，存取无序

sadd key vale :添加

smembers key :显示

srem key value:删除

s1集合 11 12 13 14

s2集合 13 14 15 16 17

sunion s1 s2//两个集合取并集

sdiff s1 s2//取s1的差集

sinter s1 s2//取交集

127.0.0.1:6379> sadd set a
(integer) 1
127.0.0.1:6379> sadd set b
(integer) 1
127.0.0.1:6379> smembers set
1) "a"
2) "b"
127.0.0.1:6379> sadd set c
(integer) 1
127.0.0.1:6379> sadd set d e f
(integer) 3
127.0.0.1:6379> smember set
(error) ERR unknown command 'smember'
127.0.0.1:6379> smembers set
1) "b"
2) "f"
3) "a"
4) "d"
5) "e"
6) "c"
127.0.0.1:6379> sadd set c
(integer) 0
127.0.0.1:6379>
127.0.0.1:6379> srem set c
(integer) 1
127.0.0.1:6379> smembers set
1) "f"
2) "a"
3) "d"
4) "e"
5) "b"
127.0.0.1:6379> sadd s1 11 12 13 14
(integer) 4
127.0.0.1:6379> sadd s2 13 14 15 16 17
(integer) 5
127.0.0.1:6379> sunion s1 s2//两个集合取并集
1) "11"
2) "12"
3) "13"
4) "14"
5) "15"
6) "16"
7) "17"
127.0.0.1:6379> sdiff s1 s2//取s1的差集:s1 - s2 == s1 - (s1 交 s2)
1) "11"
2) "12"
127.0.0.1:6379> sinter s1 s2//取交集
1) "13"
2) "14"
127.0.0.1:6379> sdiff s2 s1// s2 - s1 == s2 - (s2 交 s1)
1) "15"
2) "16"
3) "17"
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#####Sortedset有序集合类型

因为它是有序的，通过score进行排序，添加的时候也要加上

zadd key score value 添加

zrange key start temp:查

zrem key value 删

zrange key start temp withscores;连带排序分数一起查

127.0.0.1:6379> zadd sort 60 kobe
(integer) 1
127.0.0.1:6379> zadd sort 89 lily
(integer) 1
127.0.0.1:6379> zadd sort 88 miiler
(integer) 1
127.0.0.1:6379> zadd sort 34 durant
(integer) 1
127.0.0.1:6379> zrange sort 0 -1
1) "durant"
2) "kobe"
3) "miiler"
4) "lily"
127.0.0.1:6379> zrange sort 0 -1 withscores
1) "durant"
2) "34"
3) "kobe"
4) "60"
5) "miiler"
6) "88"
7) "lily"
8) "89"
127.0.0.1:6379> zrem sort lily
(integer) 1
127.0.0.1:6379> zrange sort 0 -1
1) "durant"
2) "kobe"
3) "miiler"
127.0.0.1:6379>
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二，redis和Java结合

使用springIOC容器管理redis所需要的类

2.1 搭建环境

2.1.3 引入依赖

<dependencies>
   <dependency>
       <groupId>redis.clients</groupId>
       <artifactId>jedis</artifactId>
       <version>2.7.0</version>
   </dependency>

   <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-pool2 -->

   <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-pool2</artifactId>
       <version>2.4.2</version>
   </dependency>

   <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.13.2</version>
       <scope>test</scope>
   </dependency>


   <!-- 1.Spring核心依赖 -->
   <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-core</artifactId>
       <version>4.3.7.RELEASE</version>
   </dependency>
   <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-beans</artifactId>
       <version>4.3.7.RELEASE</version>
   </dependency>
   <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-context</artifactId>
       <version>4.3.7.RELEASE</version>
   </dependency>




</dependencies>

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2.1.2 配置文件:applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:context="http://www.springframework.org/schema/context"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

<!--    开启包扫描-->
   <context:component-scan base-package="com.cq"></context:component-scan>

<!--    配置JedisPoolConfig-->
   <bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig">
       <property name="maxTotal" value="100"></property>
       <property name="maxIdle" value="100"></property>
       <property name="minIdle" value="10"></property>
       <property name="maxWaitMillis" value="20000"></property>
   </bean>
<!--    配置JedisPool-->
   <bean id="pool" class="redis.clients.jedis.JedisPool">
       <constructor-arg name="poolConfig" ref="poolConfig"></constructor-arg>
       <constructor-arg name="host" value="localhost"></constructor-arg>
   </bean>

</beans>
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2.2 测试

package com.cq;

import com.cq.utils.JedisUtils;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

/**
* @BelongsProject: day0618-redis
* @BelongsPackage: com.cq
* @Author: CodeArts
* @CreateTime: 2022-06-18  15:01
* @Description: TODO
* @Version: 1.0
*/
public class RedisTest {
   @Test
   public void test02(){
      ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
       JedisPool pool = context.getBean("pool", JedisPool.class);
       Jedis resource = pool.getResource();
       resource.set("user","wang");
       String user = resource.get("user");
       System.out.println(user);
       resource.close();

   }
}
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三，redis的综合项目SSM

通过连接数据库实现页面的下拉框

分析：前端需要接收json串然后进行数据的渲染，所以后端传给前端也要是个json串，因为这里用了redis,要先判断缓存中是否有数据有者直接返回，没有查数据库，再把数据写到缓存中,下次直接查缓存即可

1 用骨架创建web项目

2 引入依赖

<properties>
 <spring.version>5.0.2.RELEASE</spring.version>
 <slf4j.version>1.6.6</slf4j.version>
 <log4j.version>1.2.12</log4j.version>
 <oracle.version>11.2.0.1.0</oracle.version>
 <mybatis.version>3.4.5</mybatis.version>
 <spring.security.version>5.0.1.RELEASE</spring.security.version>
 <mysql.version>5.1.6</mysql.version>
</properties>

<dependencies>
 <!-- spring -->
 <dependency>
   <groupId>org.aspectj</groupId>
   <artifactId>aspectjweaver</artifactId>
   <version>1.6.8</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-aop</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-context</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-context-support</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-web</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-orm</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-beans</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-core</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-test</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-webmvc</artifactId>
   <version>${spring.version}</version>

 </dependency>
 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-tx</artifactId>
   <version>${spring.version}</version>
 </dependency>
 <dependency>
   <groupId>junit</groupId>
   <artifactId>junit</artifactId>
   <version>4.12</version>
   <scope>test</scope>
 </dependency>

 <dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>javax.servlet-api</artifactId>
   <version>3.1.0</version>
   <scope>provided</scope>
 </dependency>
 <dependency>
   <groupId>javax.servlet.jsp</groupId>
   <artifactId>jsp-api</artifactId>
   <version>2.0</version>
   <scope>provided</scope>
 </dependency>
 <dependency>
   <groupId>jstl</groupId>
   <artifactId>jstl</artifactId>
   <version>1.2</version>
 </dependency>
 <!-- log start -->
 <dependency>
   <groupId>log4j</groupId>
   <artifactId>log4j</artifactId>
   <version>${log4j.version}</version>
 </dependency>
 <dependency>
   <groupId>org.slf4j</groupId>
   <artifactId>slf4j-api</artifactId>
   <version>${slf4j.version}</version>
 </dependency>
 <dependency>
   <groupId>org.slf4j</groupId>
   <artifactId>slf4j-log4j12</artifactId>
   <version>${slf4j.version}</version>
 </dependency>
 <!-- log end -->

 <dependency>
   <groupId>org.mybatis</groupId>
   <artifactId>mybatis</artifactId>
   <version>${mybatis.version}</version>
 </dependency>
 <dependency>
   <groupId>org.mybatis</groupId>
   <artifactId>mybatis-spring</artifactId>
   <version>1.3.0</version>
 </dependency>
 <dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>druid</artifactId>
   <version>1.1.10</version>
 </dependency>

 <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>${mysql.version}</version>
 </dependency>
<!--redis-->
 <dependency>
   <groupId>redis.clients</groupId>
   <artifactId>jedis</artifactId>
   <version>2.9.0</version>
 </dependency>

 <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-test</artifactId>
   <version>${spring.version}</version>
 </dependency>

 <!--json工具-->
 <dependency>
   <groupId>com.fasterxml.jackson.core</groupId>
   <artifactId>jackson-databind</artifactId>
   <version>2.9.0</version>
 </dependency>

 <dependency>
   <groupId>com.fasterxml.jackson.core</groupId>
   <artifactId>jackson-core</artifactId>
   <version>2.9.0</version>
 </dependency>

 <dependency>
   <groupId>com.fasterxml.jackson.core</groupId>
   <artifactId>jackson-annotations</artifactId>
   <version>2.9.0</version>
 </dependency>

 <dependency>
   <groupId>junit</groupId>
   <artifactId>junit</artifactId>
   <version>4.13</version>
   <scope>test</scope>
 </dependency>
</dependencies>
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3 创建ssm结构

###4 配置文件

####4.1 applicationContext.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
<!--    开启包扫描-->
   <context:component-scan base-package="com.cq"></context:component-scan>
<!--    加载外部的propertier文件-->
   <context:property-placeholder location="classpath:db.properties"></context:property-placeholder>
<!--    配置数据源-->
   <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
       <property name="driverClassName" value="${jdbc.driver}"></property>
       <property name="url"     value="${jdbc.url}"></property>
       <property name="username" value="${jdbc.username}"></property>
       <property name="password" value="${jdbc.password}"></property>
   </bean>
<!--    配置sqlSessionFactoryBean-->
   <bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
       <property name="dataSource" ref="dataSource"></property>
   </bean>
<!--    配置MapperScannerConfigure-->
   <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
       <property name="basePackage" value="com.cq.dao"></property>
   </bean>
   
<!--    配置redis-->
<!--    配置JedisPoolConfig-->
   <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">
       <property name="maxTotal" value="${redis.pool.maxActive}"></property>
       <property name="maxIdle" value="${redis.pool.maxIdle}"></property>
       <property name="minIdle" value="${redis.pool.minIdle}"></property>
       <property name="maxWaitMillis" value="${redis.pool.maxWaitMillis}"></property>
   </bean>

<!--    配置JedisPool-->
   <bean id="jedisPool" class="redis.clients.jedis.JedisPool">
       <constructor-arg name="poolConfig" ref="jedisPoolConfig"></constructor-arg>
       <constructor-arg name="host" value="${redis.host}"></constructor-arg>
   </bean>
<!--    配置平台事务管理器-->
   <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
       <property name="dataSource" ref="dataSource"></property>
   </bean>
<!--开启注解对事务的支持-->
   <tx:annotation-driven transaction-manager="transactionManager"></tx:annotation-driven>


</beans>
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4.2 db.properties

# mysql的配置信息
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3309/day0618
jdbc.username=root
jdbc.password=root

# redis的配置信息
# 最大分配的对象数
redis.pool.maxActive=200
# 最大能够保持idel状态的对象数
redis.pool.maxIdle=50
redis.pool.minIdle=10
redis.pool.maxWaitMillis=20000

#  连接redis的主机和端口号
redis.host = 127.0.0.1

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4.3 日志文件log4j.properties

log4j.rootLogger=DEBUG,myConsole
log4j.appender.myConsole=org.apache.log4j.ConsoleAppender
log4j.appender.myConsole.ImmediateFlush=true
log4j.appender.myConsole.Target=System.out
log4j.appender.myConsole.layout=org.apache.log4j.PatternLayout
log4j.appender.myConsole.layout.ConversionPattern=[%-5p] %d(%r) --> [%t] %l: %m %x %n

log4j.logger.com.mchange.v2=ERROR
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4.4 springmvc.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
      xmlns:context="http://www.springframework.org/schema/context"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!--扫描包-->
   <context:component-scan base-package="com.cq"></context:component-scan>
   <!--配置视图解析器-->
   <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/pages/"></property>
    <property name="suffix" value=".jsp"></property>
   </bean>


<!--    开启对处理器映射器，处理器适配器的支持-->
   <mvc:annotation-driven></mvc:annotation-driven>
</beans>
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5 代码的编写

5.1 实体 City.java

package com.cq.pojo;

/**
* @BelongsProject: day0618-ssm-redis
* @BelongsPackage: com.cq.pojo
* @Author: CodeArts
* @CreateTime: 2022-06-18  15:44
* @Description: TODO
* @Version: 1.0
*/
public class City {
   private Integer id;
   private String name;

   public City() {
   }

   public City(Integer id, String name) {
       this.id = id;
       this.name = name;
   }

   public Integer getId() {
       return id;
   }

   public void setId(Integer id) {
       this.id = id;
   }

   public String getName() {
       return name;
   }

   public void setName(String name) {
       this.name = name;
   }

   @Override
   public String toString() {
       return "CityDao{" +
               "id=" + id +
               ", name='" + name + '\'' +
               '}';
   }
}
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5.2 控制层CityController.java

package com.cq.controller;

import com.cq.pojo.City;
import com.cq.service.CityService;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletResponse;
import java.util.List;

/**
* @BelongsProject: day0618-ssm-redis
* @BelongsPackage: com.cq.controller
* @Author: CodeArts
* @CreateTime: 2022-06-18  15:44
* @Description: TODO
* @Version: 1.0
*/
@Controller
@RequestMapping("city")
public class CityController {
   @Autowired
   CityService cityService;
   @RequestMapping("findAll")
   public void findAll(HttpServletResponse response) throws Exception {
      response.setContentType("application/json;charset=utf-8");
       String string = cityService.findAll();
//        System.out.println(string);
       response.getWriter().write(string);

   }
}
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5.4 service包下的CityService.java接口

package com.cq.service;

import com.cq.pojo.City;

import java.util.List;

/**
* @BelongsProject: day0618-ssm-redis
* @BelongsPackage: com.cq.service
* @Author: CodeArts
* @CreateTime: 2022-06-18  15:43
* @Description: TODO
* @Version: 1.0
*/
public interface CityService {
   String findAll();
}
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5.5 service包下的impl中改接口的实现类CityServiceImpl.java

package com.cq.service.impl;

import com.cq.dao.CityDao;
import com.cq.pojo.City;
import com.cq.service.CityService;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.StringUtils;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

import java.util.List;

/**
* @BelongsProject: day0618-ssm-redis
* @BelongsPackage: com.cq.service.impl
* @Author: CodeArts
* @CreateTime: 2022-06-18  15:50
* @Description: TODO
* @Version: 1.0
*/
@Service
public class CityServiceImpl implements CityService {
   @Autowired
   CityDao cityDao;
   @Autowired
   JedisPool jedisPool;
   public String findAll() {
       Jedis resource = jedisPool.getResource();//获取缓存连接,前提是开启了redis
       String city_name = resource.get("city_name");
       if(StringUtils.isEmpty(city_name)){//缓存中不存在
           ObjectMapper mapper = new ObjectMapper();
           try {
               //转成json串
               city_name = mapper.writeValueAsString(cityDao.findAll());
           } catch (JsonProcessingException e) {
               e.printStackTrace();
           }
           //放入缓存
           resource.set("city_name",city_name);
           return city_name;


       }else{
           System.out.println("缓存中取");
           return city_name;
       }

   }
}
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5.6 CityDao.java

package com.cq.dao;

import com.cq.pojo.City;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import javax.annotation.Resources;
import java.util.List;

/**
* @BelongsProject: day0618-ssm-redis
* @BelongsPackage: com.cq.dao
* @Author: CodeArts
* @CreateTime: 2022-06-18  15:43
* @Description: TODO
* @Version: 1.0
*/
@Repository
public interface CityDao {
   @Select("select * from city")
   public List<City> findAll();
}
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5.7 前端页面

<%--
 Created by IntelliJ IDEA.
 User: 86186
 Date: 2022/6/18
 Time: 16:23
 To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
   <title>Title</title>
</head>
<body>
<select name="province" id="province">
   <option>请选择</option>
</select>

</body>
<script src="http://libs.baidu.com/jquery/1.9.0/jquery.js"></script>
<script type="text/javascript">
   $(function () {
       $.ajax({
           type:"GET",
           url:"${pageContext.request.contextPath}/city/findAll",
           contentType:"application/json;charset=UTF-8",
           dataType:"json",
           success:function (data) {
               $(data).each(function () {
                   var option = "<option id="+this.id+">"+this.name + "</option>";
                   $("#province").append(option);

               })

           }
       })
   })
</script>
</html>

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6 web.xml配置

<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
 <display-name>Archetype Created Web Application</display-name>
<!-- 加载spring配置文件路径-->
 <context-param>
   <param-name>contextConfigLocation</param-name>
   <param-value>classpath:applicationContext.xml</param-value>
 </context-param>

 <!-- 解决中文乱码过滤器 -->
 <filter>
   <filter-name>characterEncodingFilter</filter-name>
   <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
   <init-param>
     <param-name>encoding</param-name>
     <param-value>UTF-8</param-value>
   </init-param>
 </filter>


 <filter-mapping>
   <filter-name>characterEncodingFilter</filter-name>
   <url-pattern>/*</url-pattern>
 </filter-mapping>
 <!--  配置监听器-->
 <listener>
   <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
 </listener>

 <!--配置前端控制器-->
 <servlet>
   <servlet-name>dispatcherServlet</servlet-name>
   <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
   <!--加载springmvc配置文件-->
   <init-param>
     <param-name>contextConfigLocation</param-name>
     <param-value>classpath:springmvc.xml</param-value>
   </init-param>
 </servlet>
 <servlet-mapping>
   <servlet-name>dispatcherServlet</servlet-name>
   <url-pattern>/</url-pattern>
 </servlet-mapping>
</web-app>

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效果图

相关阅读:
鸿蒙HarmonyOS实战-Web组件（请求响应和页面调试）
第1章、HDFS_核心参数
 ubuntu 修改磁盘名称
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 分析和比较深度学习框架 PyTorch 和 Tensorflow
DOM元素可编辑自定义样式获取编辑后的数据
 使用antv/X6实现流程图（包括线条动画流动，路径标签，悬浮窗口等）快速搭建流程图，DAG图等初始实践记录
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[SpringBoot] SpringBoot-04-读取yaml配置文件
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原文地址：https://blog.csdn.net/qq_43728862/article/details/125360175

Redis简单介绍以及使用

Redis

一、初始redis

1.1 redis软件

1.2 redis的数据结构,及相关命令

1.2.1 数据结构

哈希类型 hash

list 列表类型

set 集合 不重复，存取无序

二，redis和Java结合

2.1 搭建环境

2.1.3 引入依赖

2.1.2 配置文件:applicationContext.xml

2.2 测试

三，redis的综合项目SSM

1 用骨架创建web项目

2 引入依赖

3 创建ssm结构

4.2 db.properties

4.3 日志文件log4j.properties

4.4 springmvc.xml配置

5 代码的编写

5.1 实体 City.java

5.2 控制层CityController.java

5.4 service包下的CityService.java接口

5.5 service包下的impl中改接口的实现类CityServiceImpl.java

5.6 CityDao.java

5.7 前端页面

6 web.xml配置

效果图

set 集合不重复，存取无序