一、入门demo
1、pom
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>plus-cache-demo</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>3.2.4</version><relativePath/></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--尽量不要同时导入mybatis 和 mybatis_plus,避免版本差异--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-spring-boot3-starter</artifactId><version>3.5.5</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.13</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency><!--cache-->
<!-- <dependency>-->
<!-- <groupId>org.springframework.boot</groupId>-->
<!-- <artifactId>spring-boot-starter-data-redis</artifactId>-->
<!-- </dependency>-->
<!-- <dependency>-->
<!-- <groupId>org.springframework.boot</groupId>-->
<!-- <artifactId>spring-boot-starter-data-redis-reactive</artifactId>-->
<!-- </dependency>--><!-- <dependency>-->
<!-- <groupId>org.springframework.boot</groupId>-->
<!-- <artifactId>spring-boot-starter-cache</artifactId>-->
<!-- </dependency>--><!--spring-boot-starter-data-redis--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><!--spring cache--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-cache</artifactId></dependency><dependency><groupId>org.apache.commons</groupId><artifactId>commons-pool2</artifactId></dependency></dependencies>
</project>
2、配置文件
server.port=1111
server.servlet.context-path=/plusDemo
#mysql
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3308/demo?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.username=root
spring.datasource.password=wtyy
#mybatis
mybatis.mapper-locations=classpath*:mapper/*Mapper.xml
#打印日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl#redis
spring.data.redis.host=127.0.0.1
spring.data.redis.port=6379
spring.data.redis.password=
spring.data.redis.lettuce.pool.max-active=8
spring.data.redis.lettuce.pool.max-wait=-1
spring.data.redis.lettuce.pool.max-idle=8
spring.data.redis.lettuce.pool.min-idle=0
spring.data.redis.lettuce.pool.enabled=true
spring.data.redis.lettuce.pool.time-between-eviction-runs=30s
#cache
#类型指定redis
spring.cache.type=redis
#一个小时,以毫秒为单位
spring.cache.redis.time-to-live=3600000
#给缓存的建都起一个前缀。 如果指定了前缀就用我们指定的,如果没有就默认使用缓存的名字作为前缀,一般不指定
#spring.cache.redis.key-prefix=CACHE_
#指定是否使用前缀
spring.cache.redis.use-key-prefix=true
#是否缓存空值,防止缓存穿透
spring.cache.redis.cache-null-values=true
3、config
package com.pluscache.demo.config;import org.springframework.boot.autoconfigure.data.redis.RedisProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Configuration;@Configuration
@EnableCaching
@EnableConfigurationProperties(RedisProperties.class)//开启属性绑定配置的功能
public class MyCacheConfig {
}
4、controller
package com.pluscache.demo.controller;import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.pluscache.demo.dto.ParamDTO;
import com.pluscache.demo.dto.UserDTO;
import com.pluscache.demo.service.ParamService;
import com.pluscache.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.List;@RestController
@RequestMapping("/param")
public class ParamController {@Autowiredprivate ParamService paramService;@RequestMapping("/listParams")public List<ParamDTO> listParams() {return paramService.listParams();}@RequestMapping("/addParam")public void addParam(ParamDTO paramDTO) {paramService.addParam(paramDTO);}@RequestMapping("/listParamsByKey")public List<ParamDTO> listParamsByKey(String key) {return paramService.listParamsByKey(key);}@RequestMapping("/deleteById")public void deleteById(String key) {paramService.deleteByKey(key);}}
5、service
package com.pluscache.demo.service.impl;import com.pluscache.demo.dto.ParamDTO;
import com.pluscache.demo.repository.ParamRepository;
import com.pluscache.demo.service.ParamService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service("paramService")
public class ParamServiceImpl implements ParamService {@Autowiredprivate ParamRepository paramRepository;@Overridepublic List<ParamDTO> listParams() {return paramRepository.listParams();}@Overridepublic void addParam(ParamDTO paramDTO) {paramRepository.addParam(paramDTO);}@Overridepublic List<ParamDTO> listParamsByKey(String key) {return paramRepository.listParamsByKey(key);}@Overridepublic void deleteByKey(String key) {paramRepository.deleteByKey(key);}
}
6、dao
package com.pluscache.demo.repository;import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.pluscache.demo.constant.DbConstant;
import com.pluscache.demo.dto.ParamDTO;
import com.pluscache.demo.dto.UserDTO;
import com.pluscache.demo.mapper.ParamMapper;
import com.pluscache.demo.mapper.UserMapper;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheConfig;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Repository;import java.util.List;@Repository
@CacheConfig(cacheNames = {DbConstant.TABLE_PARAM_NAME_KEY_FORMAT})
@Slf4j
public class ParamRepository {@Autowiredprivate ParamMapper paramMapper;//1、无参@Cacheable(key = "#root.methodName")public List<ParamDTO> listParams() {log.info("listParams无参start");LambdaQueryWrapper<ParamDTO> queryWrapper = new LambdaQueryWrapper<>();return paramMapper.selectList(queryWrapper);}@CacheEvict(key = "#root.methodName")public void addParam(ParamDTO paramDTO) {paramMapper.insert(paramDTO);}//2、单参@Cacheable(key = "{#p0}")public List<ParamDTO> listParamsByKey(String key) {log.info("listParamsByKey有参start");LambdaQueryWrapper<ParamDTO> queryWrapper = new LambdaQueryWrapper<>();queryWrapper.eq(ParamDTO::getParamKey,key);return paramMapper.selectList(queryWrapper);}@CacheEvict(key = "{#p0}",beforeInvocation = true)public void deleteByKey(String key) {LambdaQueryWrapper<ParamDTO> queryWrapper = new LambdaQueryWrapper<>();queryWrapper.eq(ParamDTO::getParamKey,key);paramMapper.delete(queryWrapper);//int a = 1/0;}
}
package com.pluscache.demo.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.pluscache.demo.dto.ParamDTO;
import com.pluscache.demo.dto.UserDTO;
import org.apache.ibatis.annotations.Param;import java.util.List;public interface ParamMapper extends BaseMapper<ParamDTO> {void batchDeleteByKey(@Param("keys") List<String> keys);
}
7、dto与常量
package com.pluscache.demo.dto;import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;import java.io.Serializable;@Data
@TableName("t_param")
public class ParamDTO implements Serializable {private Integer id;private String paramKey;private String paramValue;
}
package com.pluscache.demo.constant;public class DbConstant {public static final String TABLE_PARAM_NAME_KEY_FORMAT = "cache:t_param:";
}
8、测试:
8.1、无参
① 第一次访问localhost:1111/plusDemo/param/listParams控制台输出:
2024-04-25T17:14:33.330+08:00 INFO 36136 --- [nio-1111-exec-2] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed.
JDBC Connection [HikariProxyConnection@644769222 wrapping com.mysql.cj.jdbc.ConnectionImpl@5ee5b9f5] will not be managed by Spring
==> Preparing: SELECT id,param_key,param_value FROM t_param
==> Parameters:
<== Columns: id, param_key, param_value
<== Row: 1, a, a_1
<== Row: 2, a, a_2
<== Total: 2
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@14369ce6]
查看redis:
② 再次访问,返回数据和第一次一样,但是控制台无输出,断点可以看到在serveimImpl直接返回了,并没有进入ParamRepository。
8.2、单参
(1)缓存与删除缓存
访问localhost:1111/plusDemo/param/listParamsByKey?key=a
第一次走db查询,后面不走db查询。查看redis:
key为t_param:::a:
value为:
访问localhost:1111/plusDemo/param/deleteById?key=a 刷新redis可以看到缓存已经被删除了
这时再访问listParamsByKey发现又走db层了
(2)删除缓存加入异常
@CacheEvict(key = "{#p0}",beforeInvocation = true)public void deleteByKey(String key) {LambdaQueryWrapper<ParamDTO> queryWrapper = new LambdaQueryWrapper<>();queryWrapper.eq(ParamDTO::getParamKey,key);paramMapper.delete(queryWrapper);int a = 1/0;}
访问localhost:1111/plusDemo/param/listParamsByKey?key=a后再访问localhost:1111/plusDemo/param/deleteById?key=a可以看到缓存已经清除了,重新走db查询
如果没有写beforeInvocation = true,仍然走缓存查询,验证beforeInvocation决定了缓存和db的先后顺序。
二、自定义KeyConstructor
对上面的demo进行改造:
① 在前面也提到了,Repository的CUD接口应该接收(集合)对象;
② 如果Repository中有多种组合key的缓存,CUD接口在@CacheEvict注解中维护key比较麻烦,所以我们可以把key组合提到自定义KeyConstructor中。