SpringBoot Redis 缓存

一、前言

Redis是内存数据库，什么是内存数据库，内存数据库是相对于硬盘数据库的。您的电脑配置是内存16G,硬盘500G，Redis的数据就是放在16G内存中，Mysql数据就放在500G硬盘中。

内存读写速度快，所以Redis数据库快，那它可以做缓存和一些访问率高的数据存储。

因为是内存数据库，所以Redis存储容量小，而且断电了数据会丢失。
所以Redis不要存储数据量大的数据，对于断电数据丢失，redis有两种持久化策略(记录命令和定时刷盘)，这些后续再说。

废话不多话，SpringBoot集成Redis，直接上代码。

二、目录结构和配置

2.1 目录结构

QQ截图20210515114031.png

2.2 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.llh</groupId>
    <artifactId>spring-boot-redis</artifactId>
    <version>1.0.0</version>
    <name>spring-boot-redis</name>
    <description>spring-boot-redis project description</description>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
    </dependencies>

</project>

• 就是加了这个 spring-boot-starter-data-redis依赖

---

2.3 application.properties

# 应用名称
spring.application.name=spring-boot-redis
server.port=8888
# redis 地址
spring.redis.host=localhost
spring.redis.port=6379

• 主要就是redis的地址 端口配置

三、代码

RedisConfiguration 类

package com.llh.springbootredis.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.serializer.JdkSerializationRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

/**
 * @author llh
 */
@Configuration
public class RedisConfiguration {
    private final RedisConnectionFactory redisConnectionFactory;

    @Autowired
    public RedisConfiguration(RedisConnectionFactory redisConnectionFactory) {
        this.redisConnectionFactory = redisConnectionFactory;
    }

    @Bean()
    public RedisTemplate<String, Object> redisTemplate() {
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(new JdkSerializationRedisSerializer());
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        return redisTemplate;
    }

    @Bean
    public StringRedisTemplate stringRedisTemplate() {
        StringRedisTemplate stringRedisTemplate = new StringRedisTemplate();
        stringRedisTemplate.setConnectionFactory(redisConnectionFactory);
        return stringRedisTemplate;
    }

}

• 这里主要就是注入redisTemplate 和 stringRedisTemplate对象
• redisTemplate 是可以操作对象的，里面配置了对象的序列化方式
• stringRedisTemplate 只能操作字符串

---

UserInfo 类

package com.llh.springbootredis.bean;

import java.io.Serializable;

/**
 * @author llh
 */
public class UserInfo implements Serializable {
    private static final long serialVersionUID = -4514567603228180464L;

    private Long id;
    private String username;
    private String password;

    public UserInfo(Long id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public Long getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "UserInfo{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

• 实体类一定要实现Serializable接口，因为对象要序列化保存

---

TestService 类

package com.llh.springbootredis.service;

import com.llh.springbootredis.bean.UserInfo;

/**
 * @author llh
 */
public interface TestService {
    String test0(Long id);

    UserInfo test1(Long id);
}

---

TestServiceImpl 类

package com.llh.springbootredis.service.impl;

import com.llh.springbootredis.bean.UserInfo;
import com.llh.springbootredis.service.TestService;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.UUID;

/**
 * @author llh
 */
@Service
public class TestServiceImpl implements TestService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedisTemplate<String, Object> redisTemplate;

    @Override
    public String test0(Long id) {
        // 模拟延迟操作
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("产生一个新字符串");
        UUID uuid = UUID.randomUUID();
        String str = uuid.toString();

        String cacheKey = "str:" + id;
        System.out.println("redis缓存此字符串 " + cacheKey + " ===> " + str);
        stringRedisTemplate.opsForValue().set(cacheKey, str);
        return str;
    }

    @Override
    public UserInfo test1(Long id) {
        // 模拟延迟操作
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("产生一个新对象");
        UserInfo userInfo = new UserInfo(id, "admin", "123456");

        String cacheKey = "user:" + id;
        System.out.println("redis缓存此对象 " + cacheKey + " ===> " + userInfo);
        redisTemplate.opsForValue().set(cacheKey, userInfo);
        return userInfo;
    }
}

• stringRedisTemplate.opsForValue().set(cacheKey, str);主要就是这一句，将数据保存到Redis数据库。

---

TestController 类

package com.llh.springbootredis.controller;

import com.llh.springbootredis.bean.UserInfo;
import com.llh.springbootredis.service.TestService;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

/**
 * @author llh
 */
@RestController
public class TestController {
    @Resource
    private TestService testService;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedisTemplate<String, Object> redisTemplate;

    @GetMapping("test0/{id}")
    public String test0(@PathVariable Long id) {
        // 查询缓存
        String cacheKey = "str:" + id;
        String cacheVal = stringRedisTemplate.opsForValue().get(cacheKey);
        if (cacheVal != null) {
            System.out.println("redis缓存中直接返回字符串");
            return cacheVal;
        }
        return testService.test0(id);
    }

    @GetMapping("test1/{id}")
    public UserInfo test1(@PathVariable Long id) {
        // 查询缓存
        String cacheKey = "user:" + id;
        UserInfo cacheVal = (UserInfo) redisTemplate.opsForValue().get(cacheKey);
        if (cacheVal != null) {
            System.out.println("redis缓存中直接返回对象");
            return cacheVal;
        }
        return testService.test1(id);
    }
}

• stringRedisTemplate.opsForValue().get(cacheKey)获取缓存的数据。
• 缓存的Key都是字符串
• 缓存的Value，test0接口是字符串 test1接口是对象
• 通过id来缓存的，为了区分数据类型，字符串Key的前缀是str:,对象Key的前缀是user:

四、测试

• localhost:8888/test0/1
• localhost:8888/test0/2
• localhost:8888/test1/1
• localhost:8888/test1/2

QQ截图20210515120258.png QQ截图20210515120558.png

• 打印的日志可以看到相同的请求第一次是创建新的对象，第二次直接从Redis中获取，从Redis中获取速度是非常快的。
• Redis数据库中也有了4条数据。

五、总结

Redis应该是目前使用最多的内存数据库了，除了做缓存之外，根据Redis的数据类型特性还可以做很多好玩的东西。比如分布式锁，点赞评论等。我们这里只用到了最简单的Key->String类型。它还有Key->List,Key->Map,Key->Set,Key->ZSet等。

GitHub源码地址：https://github.com/tigerleeli/xiaohuge-blog/tree/master/spring-boot-redis