什么是缓存
缓存是⼀个高速数据交换的存储器,使用它可以快速的访问和操作数据。
举个通俗的例子。
小明经营着一家饭店,在刚开张的时候由于名气不足,客源少,生意并不是很忙,平时没事的时候就闲着,有客人来了再进厨房安排做菜。随着饭店的日益发展,此时的饭店已经不同往日,有着大量的稳定客源,并且在某些节假日的时候甚至爆满。按照以前的做法,那肯定是行不通了,在用餐高峰期的时候因为备餐慢导致了客户的长时间等待,使得饭店的屡遭投诉。
为解决这一问题,小明想到了一个办法,可以在空闲的时候,提前将热门的菜做完后放入保温柜,等用餐高峰期时再拿出来加热后就可以直接上菜,就规避了短时间内大量客源而导致的备餐慢的问题,通过这一方法,即使在高峰期,也能很好的应对。
这就是缓存的本质,将热点资源(高频读、低频写)提前放入离用户最近、访问速度更快的地方,以提高访问速度。
为什么要用缓存
使用缓存后,效率会大大的提升,减少了不必要的资源消耗,提升了用户体验。
redis的特点:
- redis支持数据的持久化,可以将内存中的数据保存在磁盘中,重启的时候可以再次加在进行使用。
- redis不仅仅支持简单的key-value类型的数据,同时还提供list,set,zset,hash等数据结构的储存
- redis支持数据的备份,即master-slave模式的数据备份
redis的优势:
- 性能极高——redis能读得的速度是110000次/s,写的速度是81000次/s。
- 丰富的数据类型——redis支持二进制案例的Strings, Lists, Hashes, Sets 及 Ordered Sets 数据类型操作。
- 原子——redis的所有操作都是原子性的,意思就是要么成功执行要么失败完全不执行。单个操作是原子性的。多个操作也支持事务,即原子性,通过multi和exec指令包起来。
- 丰富的特性redis还支持publish/subscribe,通知,key过期等等特性
Redis为什么这么快
(1)完全基于内存,数据存在内存中,绝大部分请求是纯粹的内存操作,非常快速,跟传统的磁盘文件数据存储相比,避免了通过磁盘IO读取到内存这部分的开销。
(2)数据结构简单,对数据操作也简单。Redis中的数据结构是专门进行设计的,每种数据结构都有一种或多种数据结构来支持。Redis正是依赖这些灵活的数据结构,来提升读取和写入的性能。
(3)采用单线程,省去了很多上下文切换的时间以及CPU消耗,不存在竞争条件,不用去考虑各种锁的问题,不存在加锁释放锁操作,也不会出现死锁而导致的性能消耗。
(4)使用基于IO多路复用机制的线程模型,可以处理并发的链接。
实现一个用户信息的缓存
数据库表结构:
CREATE TABLE `blade_user` (
`id` bigint(20) NOT NULL COMMENT '主键',
`tenant_id` varchar(12) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT '000000' COMMENT '租户ID',
`code` varchar(12) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '用户编号',
`user_type` int(11) DEFAULT NULL COMMENT '用户平台',
`account` varchar(45) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '账号',
`password` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '密码',
`name` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '昵称',
`real_name` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '真名',
`avatar` varchar(500) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '头像',
`email` varchar(45) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '邮箱',
`phone` varchar(45) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '手机',
`birthday` datetime DEFAULT NULL COMMENT '生日',
`sex` int(11) DEFAULT NULL COMMENT '性别',
`role_id` varchar(1000) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '角色id',
`dept_id` varchar(1000) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '部门id',
`post_id` varchar(1000) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '岗位id',
`create_user` bigint(20) DEFAULT NULL COMMENT '创建人',
`create_dept` bigint(20) DEFAULT NULL COMMENT '创建部门',
`create_time` datetime DEFAULT NULL COMMENT '创建时间',
`update_user` bigint(20) DEFAULT NULL COMMENT '修改人',
`update_time` datetime DEFAULT NULL COMMENT '修改时间',
`status` int(11) DEFAULT NULL COMMENT '状态',
`is_deleted` int(11) DEFAULT '0' COMMENT '是否已删除',
PRIMARY KEY (`id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci ROW_FORMAT=DYNAMIC COMMENT='用户表';
方式一:利用RedisTemplate实现 导入依赖
完整pom.xml文件:
<?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">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.8</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.redis.demo</groupId>
<artifactId>springboot-redis</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot-redis</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!--mybatis-plus的springboot支持-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.4.2</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!--mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
</dependency>
<!-- hutool 工具包,各种封装功能 一应俱全-->
<dependency>
<groupId>cn.hutool</groupId>
<artifactId>hutool-all</artifactId>
<version>5.8.5</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.41</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-cache</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>
添加配置
application.yml文件:
server:
port: 8081
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://3.129.36.183:3306/test?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=UTF-8
username: root
password: root
#redis
redis:
host: 3.129.36.183
#Redis服务器连接端口
port: 6379
#Redis服务器连接密码
password: 123456
mybatis-plus:
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #开启sql日志
# 将带有下划线的表字段映射为驼峰格式的实体类属性
map-underscore-to-camel-case: true
#配置类型别名所对应的包
type-aliases-package: com.redis.demo.entity
#配置SQL输出语句com.winsun.dataclean.mapper
mapper-locations: com/redis/demo/dao
@Component
public class RedisUtils {
@Autowired
private RedisTemplate redisTemplate;
// =============================common============================
public boolean expire(String key, long time) {
try {
if (time > 0) {
redisTemplate.expire(key, time, TimeUnit.SECONDS);
}
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public long getExpire(String key) {
return redisTemplate.getExpire(key, TimeUnit.SECONDS);
}
public boolean hasKey(String key) {
try {
return redisTemplate.hasKey(key);
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
@SuppressWarnings("unchecked")
public void del(String... key) {
if (key != null && key.length > 0) {
if (key.length == 1) {
redisTemplate.delete(key[0]);
} else {
redisTemplate.delete(CollectionUtils.arrayToList(key));
}
}
}
// ============================String=============================
public Object get(String key) {
return key == null ? null : redisTemplate.opsForValue().get(key);
}
public boolean set(String key, Object value) {
try {
redisTemplate.opsForValue().set(key, value);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean set(String key, Object value, long time) {
try {
if (time > 0) {
redisTemplate.opsForValue().set(key, value, time, TimeUnit.SECONDS);
} else {
set(key, value);
}
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public long incr(String key, long delta) {
if (delta < 0) {
throw new RuntimeException("递增因子必须大于0");
}
return redisTemplate.opsForValue().increment(key, delta);
}
public long decr(String key, long delta) {
if (delta < 0) {
throw new RuntimeException("递减因子必须大于0");
}
return redisTemplate.opsForValue().increment(key, -delta);
}
// ================================Map=================================
public Object hget(String key, String item) {
return redisTemplate.opsForHash().get(key, item);
}
public Map<Object, Object> hmget(String key) {
return redisTemplate.opsForHash().entries(key);
}
public boolean hmset(String key, Map<String, Object> map) {
try {
redisTemplate.opsForHash().putAll(key, map);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean hmset(String key, Map<String, Object> map, long time) {
try {
redisTemplate.opsForHash().putAll(key, map);
if (time > 0) {
expire(key, time);
}
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean hset(String key, String item, Object value) {
try {
redisTemplate.opsForHash().put(key, item, value);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean hset(String key, String item, Object value, long time) {
try {
redisTemplate.opsForHash().put(key, item, value);
if (time > 0) {
expire(key, time);
}
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public void hdel(String key, Object... item) {
redisTemplate.opsForHash().delete(key, item);
}
public boolean hHasKey(String key, String item) {
return redisTemplate.opsForHash().hasKey(key, item);
}
public double hincr(String key, String item, double by) {
return redisTemplate.opsForHash().increment(key, item, by);
}
public double hdecr(String key, String item, double by) {
return redisTemplate.opsForHash().increment(key, item, -by);
}
// ============================set=============================
public Set<Object> sGet(String key) {
try {
return redisTemplate.opsForSet().members(key);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public boolean sHasKey(String key, Object value) {
try {
return redisTemplate.opsForSet().isMember(key, value);
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public long sSet(String key, Object... values) {
try {
return redisTemplate.opsForSet().add(key, values);
} catch (Exception e) {
e.printStackTrace();
return 0;
}
}
public long sSetAndTime(String key, long time, Object... values) {
try {
Long count = redisTemplate.opsForSet().add(key, values);
if (time > 0)
expire(key, time);
return count;
} catch (Exception e) {
e.printStackTrace();
return 0;
}
}
public long sGetSetSize(String key) {
try {
return redisTemplate.opsForSet().size(key);
} catch (Exception e) {
e.printStackTrace();
return 0;
}
}
public long setRemove(String key, Object... values) {
try {
Long count = redisTemplate.opsForSet().remove(key, values);
return count;
} catch (Exception e) {
e.printStackTrace();
return 0;
}
}
// ===============================list=================================
public List<Object> lGet(String key, long start, long end) {
try {
return redisTemplate.opsForList().range(key, start, end);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public long lGetListSize(String key) {
try {
return redisTemplate.opsForList().size(key);
} catch (Exception e) {
e.printStackTrace();
return 0;
}
}
public Object lGetIndex(String key, long index) {
try {
return redisTemplate.opsForList().index(key, index);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public boolean lSet(String key, Object value) {
try {
redisTemplate.opsForList().rightPush(key, value);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean lSet(String key, Object value, long time) {
try {
redisTemplate.opsForList().rightPush(key, value);
if (time > 0)
expire(key, time);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean lSet(String key, List<Object> value) {
try {
redisTemplate.opsForList().rightPushAll(key, value);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean lSet(String key, List<Object> value, long time) {
try {
redisTemplate.opsForList().rightPushAll(key, value);
if (time > 0)
expire(key, time);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public boolean lUpdateIndex(String key, long index, Object value) {
try {
redisTemplate.opsForList().set(key, index, value);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public long lRemove(String key, long count, Object value) {
try {
Long remove = redisTemplate.opsForList().remove(key, count, value);
return remove;
} catch (Exception e) {
e.printStackTrace();
return 0;
}
}
}
RedisConfig:
package com.redis.demo.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.redis.demo.utils.MapUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.interceptor.KeyGenerator;
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.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializer;
import javax.annotation.PostConstruct;
import java.util.Map;
@Configuration
public class RedisConfig {
@Autowired
private RedisTemplate redisTemplate;
@PostConstruct
public void init() {
initRedisTemplate();
}
private void initRedisTemplate() {
RedisSerializer stringSerializer = redisTemplate.getStringSerializer();
redisTemplate.setKeySerializer(stringSerializer);
redisTemplate.setHashKeySerializer(stringSerializer);
redisTemplate.setValueSerializer(stringSerializer);
redisTemplate.setHashValueSerializer(stringSerializer);
}
}
开发mapper接口
package com.redis.demo.dao;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.redis.demo.entity.BladeUser;
public interface BladeUserMapper extends BaseMapper<BladeUser> {
}
service层
IBladeUserService:
package com.redis.demo.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.redis.demo.entity.BladeUser;
import com.redis.demo.result.DealResult;
public interface IBladeUserService extends IService<BladeUser> {
DealResult getById(Long id);
}
BladeUserServiceImpl:
package com.redis.demo.service.impl;
import cn.hutool.core.bean.BeanUtil;
import cn.hutool.json.JSONUtil;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.redis.demo.constant.RedisConstants;
import com.redis.demo.dao.BladeUserMapper;
import com.redis.demo.entity.BladeUser;
import com.redis.demo.result.DealResult;
import com.redis.demo.service.IBladeUserService;
import com.redis.demo.status.CacheNameStatus;
import com.redis.demo.utils.RedisUtils;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.util.ObjectUtils;
@Service
public class BladeUserServiceImpl extends ServiceImpl<BladeUserMapper, BladeUser> implements IBladeUserService {
@Autowired
private RedisUtils redisUtils;
@Override
public DealResult getById(Long id) {
String userKey = RedisConstants.CACHE_USER_KEY+id;
Object user = redisUtils.get(userKey);
if (!ObjectUtils.isEmpty(user)){
return DealResult.data(JSONUtil.toBean(JSONUtil.toJsonStr(user),BladeUser.class));
}
BladeUser bladeUser = baseMapper.selectById(id);
redisUtils.set(userKey, JSON.toJSONString(bladeUser));
return DealResult.data(bladeUser);
}
}
controller层
package com.redis.demo.controller;
import com.redis.demo.result.DealResult;
import com.redis.demo.service.IBladeUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/bladeUser")
public class BladeUserController {
@Autowired
private IBladeUserService bladeUserService;
@RequestMapping("getById/{id}")
public DealResult getById(@PathVariable("id")Long id){
return bladeUserService.getById(id);
}
}
测试
启动项目,使用postman访问该接口,连续请求两次,观察响应时长:
第一次:
第二次:
可以看到,第一次3.34s,第二次43ms,效率明显提高!
方式二:采用SpringBoot注解开启缓存
以方式一为准
在启动类添加@EnableCaching
注解
修改service层实现类代码
package com.redis.demo.service.impl;
import cn.hutool.core.bean.BeanUtil;
import cn.hutool.json.JSONUtil;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.redis.demo.constant.RedisConstants;
import com.redis.demo.dao.BladeUserMapper;
import com.redis.demo.entity.BladeUser;
import com.redis.demo.result.DealResult;
import com.redis.demo.service.IBladeUserService;
import com.redis.demo.status.CacheNameStatus;
import com.redis.demo.utils.RedisUtils;
import lombok.AllArgsConstructor;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.util.ObjectUtils;
@Service
public class BladeUserServiceImpl extends ServiceImpl<BladeUserMapper, BladeUser> implements IBladeUserService {
@Autowired
private RedisUtils redisUtils;
// @Override
// public DealResult getById(Long id) {
//
// String userKey = RedisConstants.CACHE_USER_KEY+id;
// Object user = redisUtils.get(userKey);
// if (!ObjectUtils.isEmpty(user)){
//
// return DealResult.data(JSONUtil.toBean(JSONUtil.toJsonStr(user),BladeUser.class));
// }
//
// BladeUser bladeUser = baseMapper.selectById(id);
// redisUtils.set(userKey, JSON.toJSONString(bladeUser));
// return DealResult.data(bladeUser);
// }
@Cacheable(cacheNames = CacheNameStatus.BLADE_USER,keyGenerator = CacheNameStatus.KEY_GENERATOR)
@Override
public DealResult getById(Long id) {
BladeUser bladeUser = baseMapper.selectById(id);
return DealResult.data(bladeUser);
}
}
修改RedisConfig配置类
在配置类中添加自定义KeyGenerator
@Bean
public KeyGenerator simpleKeyGenerator() {
return (o, method, objects) -> {
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append(o.getClass().getSimpleName());
stringBuilder.append(".");
stringBuilder.append(method.getName());
stringBuilder.append("[");
for (Object obj : objects) {
if(obj.toString().indexOf("Vo@")!= -1)
{
Map<String, Object> map = MapUtil.getAttrFromModel(obj);
stringBuilder.append("[");
for(String item:map.keySet())
{
stringBuilder.append(",");
stringBuilder.append(map.get(item));
}
stringBuilder.append(",");
stringBuilder.deleteCharAt(stringBuilder.length() - 1);
stringBuilder.append("]");
}
else {
stringBuilder.append(obj);
stringBuilder.append(",");
}
}
stringBuilder.append("]");
return stringBuilder.toString();
};
}
注:关于 @Cacheable
注解的参数,不懂的可以点击查看。
重启项目,再次访问以上接口,观察响应时间:
第一次:
第二次:
可以看到,第一次2.52s,第二次44ms,效率明显提高!
通过Redis可视化工具观察缓存数据:
通过观察缓存数据大小可知:方式一449字节,方式二976字节,如果从内存占用大小的角度考虑,博主认为使用RedisTemplate
方式做缓存更合适,因为这种方式所占内存相对较少。
以上就是该篇文章的所有内容,代码已上传至git:https://gitee.com/lianaozhe/springboot-redis.git
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