Redis介绍及整合Spring

时间:2024-10-02 08:40:27

目录

 

Redis介绍

Spring与Redis集成


Redis介绍

        Redis是内存数据库,Key-value型NOSQL数据库,项目上经常将一些不经常变化并且反复查询的数据放入Redis缓存,由于数据放在内存中,所以查询、维护的速度远远快于硬盘方式操作数据(关系型数据库)。

        Redis的数据存储在内存中,同时也会持久化到硬盘中,极端情况Redis服务器宕机时,缓存数据也可以从硬盘中恢复。

        Redis的常用配置(配置文件redis.conf)如下:

  • daemonize yes   设置 Redis 以守护进程方式运行,启动后台运行

  • port 6379 设置 Redis 监听的端口,默认为 6379

  • logfile "/var/log/redis/redis-server.log"  设置 Redis 日志文件路径

  • databases 16  设置数据库数量,默认16个数据库 (0...15)

  • dir 设置数据文件目录

  • requirepass yourpassword  设置 Redis 密码

  • tcp-keepalive 300 设置客户端空闲超时时间

        Redis操作缓存常用命令如下:

  • select 选择数据库,select 0 选择0号数据库
  • set 存放数据,命令格式为 set key value
  • get 获取数据,命令格式为 get key
  • keys 命令可以取符合规则的键值列表,通常情况可以结合*、?等选项来使用
  • exists 命令可以判断键值是否存在
  • del 命令可以删除当前数据库的指定 key

Spring与Redis集成

1、增加依赖【pom.xml】

重点依赖说明:jedis是java操作redis的客户端;spring-data-redis 是Spring和redis的集成包

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.20.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-redis</artifactId>
            <version>2.3.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
            <version>3.7.1</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

2、Redis配置

Redis配置文件【redis_config.properties】

spring.redis.host=ip
spring.redis.port=port
spring.redis.password=password
spring.redis.database=0

Redis配置类【RedisConfig】,Spring IOC容器管理 

package com.text.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.StringRedisSerializer;

@Configuration
@PropertySource("classpath:redis_config.properties")
public class RedisConfig {
    @Value("${spring.redis.host}")
    private String host;
    @Value("${spring.redis.port}")
    private Integer port;
    @Value("${spring.redis.password}")
    private String password;
    @Value("${spring.redis.database}")
    private Integer database;

    @Bean
    public RedisConnectionFactory redisConnectionFactory() {
        RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration();
        redisStandaloneConfiguration.setHostName(host);
        redisStandaloneConfiguration.setPort(port);
        redisStandaloneConfiguration.setPassword(password);
        redisStandaloneConfiguration.setDatabase(database);
        RedisConnectionFactory redisConnectionFactory = new JedisConnectionFactory(redisStandaloneConfiguration);
        return redisConnectionFactory;
    }
    @Bean
    public RedisTemplate redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate redisTemplate = new RedisTemplate();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        //设置key值的序列化方式,默认是JDK的形式
        redisTemplate.setKeySerializer(StringRedisSerializer.UTF_8);
        return redisTemplate;
    }
}

重点代码说明: 

  • host ,port等属性值,来自于配置属性文件redis_config.properties
  • 通过配置生成了RedisConnectionFactory,IOC容器管理
  • 通过RedisConnectionFactory实例参数生成了RedisTemplate 实例,此实例对象就可以对Redis进行CRUD操作,IOC容器管理

Spring配置:此配置比较简单,只是开启了注解扫描包

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:task="http://www.springframework.org/schema/task"
       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/task
            http://www.springframework.org/schema/task/spring-task.xsd
            http://www.springframework.org/schema/tx
            http://www.springframework.org/schema/tx/spring-tx.xsd">
    <context:component-scan base-package="com.text"/>
</beans>

3、测试类

package com.text.test;

import com.text.entity.Student;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

@Component
public class Application {
    @Resource
    private RedisTemplate redisTemplate;
    public void testRedis() {
        Student s1 = new Student("1","张三",18);
        Student s2 = new Student("2","李四",19);
        Student s3 = new Student("3","王五",20);
        redisTemplate.opsForValue().set(s1.getId(),s1);
        redisTemplate.opsForValue().set(s2.getId(),s2);
        redisTemplate.opsForValue().set(s3.getId(),s3);

        Student student = (Student)redisTemplate.opsForValue().get(s3.getId());
        System.out.println(student);
    }
    public static void main(String[] args) throws Exception {
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
        RedisTemplate redisTemplate = context.getBean("redisTemplate", RedisTemplate.class);
        System.out.println("redisTemplate:" + redisTemplate);
        Application application = context.getBean("application", Application.class);
        System.out.println("application:" + application);
        application.testRedis();
    }
}

重点代码说明:

  • 运行main程序后,spring容器启动,相关的对象都被实例化,包括Application,通过该实例对象注入的redisTemplate对象 set/get方法对Redis缓存进行操作。
  • Student 对象需要序列化
package com.text.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student implements Serializable {
    private String id;
    private String name;
    private int age;
}

运行结果:

从运行结果可以看出,学生对象已经被加入缓存并且可以从缓存中读取出来,符合预期