Caffenie配合Redis做两级缓存

一、什么是两级缓存

在项目中。一级缓存用Caffeine，二级缓存用Redis，查询数据时首先查本地的Caffeine缓存，没有命中再通过网络去访问Redis缓存，还是没有命中再查数据库。具体流程如下

二、简单的二级缓存实现-v1

目录结构

2.1 double-cache模块主要文件

pom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 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>double-cache</artifactId><version>1.0-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.2</version><relativePath/></parent><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId></dependency><dependency><groupId>com.github.ben-manes.caffeine</groupId><artifactId>caffeine</artifactId><version>2.9.2</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency></dependencies></project>

2.2 测试模块的主要文件

OrderServiceImpl

@Slf4j
@Service
@RequiredArgsConstructor
public class OrderServiceImpl extends ServiceImpl<OrderMapper, Order> implements OrderService {private final OrderMapper orderMapper;private final Cache cache;private final RedisTemplate redisTemplate;@Overridepublic Order getOrderById(Long id) {String key = CacheConstant.ORDER + id;Order order = (Order) cache.get(key,k -> {//先查询 RedisObject obj = redisTemplate.opsForValue().get(k);if (Objects.nonNull(obj)) {log.info("get data from redis");return obj;}// Redis没有则查询 DBlog.info("get data from database");Order myOrder = orderMapper.selectOne(new LambdaQueryWrapper<Order>().eq(Order::getId, id));redisTemplate.opsForValue().set(k, myOrder, 120, TimeUnit.SECONDS);return myOrder;});return order;}@Overridepublic void updateOrder(Order order) {log.info("update order data");String key = CacheConstant.ORDER + order.getId();orderMapper.updateById(order);//修改 RedisredisTemplate.opsForValue().set(key, order, 120, TimeUnit.SECONDS);// 修改本地缓存cache.put(key, order);}@Overridepublic void deleteOrder(Long id) {log.info("delete order");orderMapper.deleteById(id);String key = CacheConstant.ORDER + id;redisTemplate.delete(key);cache.invalidate(key);}
}

application.yml

server:port: 8090spring:application:name: test-demodatasource:url: jdbc:mysql://localhost:3306/ktl?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTCusername: rootpassword: rootdriver-class-name: com.mysql.cj.jdbc.Driverredis:host: 192.168.200.131port: 6379database: 0timeout: 10000mslettuce:pool:max-active: 8max-wait: -1msmax-idle: 8min-idle: 0password: rootlogging:level:com.cn.dc: debugorg.springframework: warn

pom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 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>testcache</artifactId><version>1.0-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.2</version><relativePath/></parent><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><mybatis-plus.version>3.3.2</mybatis-plus.version></properties><dependencies><dependency><groupId>org.example</groupId><artifactId>double-cache</artifactId><version>1.0-SNAPSHOT</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.apache.commons</groupId><artifactId>commons-pool2</artifactId><version>2.8.1</version></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>${mybatis-plus.version}</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.12</version><scope>provided</scope></dependency></dependencies>
</project>

2.3 测试

测试get/{id}接口的时候，会把从db查出来的数据放入到redis和Caffeine中，在有效期内不需要再次从数据库查询

三、二级缓存实现-v2

v1的代码入侵性很强，因此加入了注解@Cacheable，@CachePut，@CacheEvict

3.1 double-cache模块

3.2 测试模块

OrderServiceImpl

@Slf4j
@Service
@RequiredArgsConstructor
public class OrderServiceImpl extends ServiceImpl<OrderMapper, Order> implements OrderService {private final OrderMapper orderMapper;private final RedisTemplate redisTemplate;@Override@Cacheable(value = "order",key = "#id")
//@Cacheable(cacheNames = "order",key = "#p0")public Order getOrderById(Long id) {String key= CacheConstant.ORDER + id;//先查询 RedisObject obj = redisTemplate.opsForValue().get(key);if (Objects.nonNull(obj)){log.info("get data from redis");return (Order) obj;}// Redis没有则查询 DBlog.info("get data from database");Order myOrder = orderMapper.selectOne(new LambdaQueryWrapper<Order>().eq(Order::getId, id));redisTemplate.opsForValue().set(key,myOrder,120, TimeUnit.SECONDS);return myOrder;}@Override@CachePut(cacheNames = "order",key = "#order.id")public Order updateOrder(Order order) {log.info("update order data");orderMapper.updateById(order);//修改 RedisredisTemplate.opsForValue().set(CacheConstant.ORDER + order.getId(),order, 120, TimeUnit.SECONDS);return order;}@Override@CacheEvict(cacheNames = "order",key = "#id")public void deleteOrder(Long id) {log.info("delete order");orderMapper.deleteById(id);redisTemplate.delete(CacheConstant.ORDER + id);}
}

四、二级缓存实现-v3

模仿spring通过注解管理缓存的方式，我们也可以选择自定义注解，然后在切面中处理缓存，从而将对业务代码的入侵降到最低。

首先定义一个注解，用于添加在需要操作缓存的方法上：

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DoubleCache {String cacheName();String key();	//支持springEl表达式long l2TimeOut() default 120;CacheType type() default CacheType.FULL;
}

我们使用cacheName + key作为缓存的真正key（仅存在一个Cache中，不做CacheName隔离），l2TimeOut为可以设置的二级缓存Redis的过期时间，type是一个枚举类型的变量，表示操作缓存的类型，枚举类型定义如下：

public enum CacheType {FULL,   //存取PUT,    //只存DELETE  //删除
}

因为要使key支持springEl表达式，所以需要写一个方法，使用表达式解析器解析参数：

public class ElParser {public static String parse(String elString, TreeMap<String,Object> map){elString=String.format("#{%s}",elString);//创建表达式解析器ExpressionParser parser = new SpelExpressionParser();//通过evaluationContext.setVariable可以在上下文中设定变量。EvaluationContext context = new StandardEvaluationContext();map.entrySet().forEach(entry->context.setVariable(entry.getKey(),entry.getValue()));//解析表达式Expression expression = parser.parseExpression(elString, new TemplateParserContext());//使用Expression.getValue()获取表达式的值，这里传入了Evaluation上下文String value = expression.getValue(context, String.class);return value;}
}

至于Cache相关参数的配置，我们沿用V1版本中的配置即可。准备工作做完了，下面我们定义切面，在切面中操作Cache来读写Caffeine的缓存，操作RedisTemplate读写Redis缓存。

@Slf4j
@Component
@Aspect
@AllArgsConstructor
public class CacheAspect {private final Cache cache;private final RedisTemplate redisTemplate;private final String COLON = ":";@Pointcut("@annotation(org.example.doublecache.annotation.DoubleCache)")public void cacheAspect() {}@Around("cacheAspect()")public Object doAround(ProceedingJoinPoint point) throws Throwable {MethodSignature signature = (MethodSignature) point.getSignature();Method method = signature.getMethod();//        if (!method.isAnnotationPresent(DoubleCache.class))
//            return null;//拼接解析springEl表达式的mapString[] paramNames = signature.getParameterNames();Object[] args = point.getArgs();TreeMap<String, Object> treeMap = new TreeMap<>();for (int i = 0; i < paramNames.length; i++) {treeMap.put(paramNames[i],args[i]);}DoubleCache annotation = method.getAnnotation(DoubleCache.class);String elResult = ElParser.parse(annotation.key(), treeMap);String realKey = annotation.cacheName() + COLON + elResult;//强制更新if (annotation.type()== CacheType.PUT){Object object = point.proceed();redisTemplate.opsForValue().set(realKey, object,annotation.l2TimeOut(), TimeUnit.SECONDS);cache.put(realKey, object);return object;}//删除else if (annotation.type()== CacheType.DELETE){redisTemplate.delete(realKey);cache.invalidate(realKey);return point.proceed();}//读写，查询CaffeineObject caffeineCache = cache.getIfPresent(realKey);if (Objects.nonNull(caffeineCache)) {log.info("get data from caffeine");return caffeineCache;}//查询RedisObject redisCache = redisTemplate.opsForValue().get(realKey);if (Objects.nonNull(redisCache)) {log.info("get data from redis");cache.put(realKey, redisCache);return redisCache;}log.info("get data from database");Object object = point.proceed();if (Objects.nonNull(object)){//写回RedisredisTemplate.opsForValue().set(realKey, object,annotation.l2TimeOut(), TimeUnit.SECONDS);//写入Caffeinecache.put(realKey, object);}return object;}
}

4.1 double-cache模块

4.2 测试模块

OrderServiceImpl修改如下

@Slf4j
@Service
@RequiredArgsConstructor
public class OrderServiceImpl extends ServiceImpl<OrderMapper, Order> implements OrderService {private final OrderMapper orderMapper;@Override@DoubleCache(cacheName = "order", key = "#id",type = CacheType.FULL)public Order getOrderById(Long id) {Order myOrder = orderMapper.selectOne(new LambdaQueryWrapper<Order>().eq(Order::getId, id));return myOrder;}@Override@DoubleCache(cacheName = "order",key = "#order.id",type = CacheType.PUT)public Order updateOrder(Order order) {orderMapper.updateById(order);return order;}@Override@DoubleCache(cacheName = "order",key = "#id",type = CacheType.DELETE)public void deleteOrder(Long id) {orderMapper.deleteById(id);}@Override@DoubleCache(cacheName = "order",key = "#id")public Order getOrderByIdAndStatus(Long id,Integer status) {Order myOrder = orderMapper.selectOne(new LambdaQueryWrapper<Order>().eq(Order::getId, id).eq(Order::getStatus,status));return myOrder;}

在TestApplication上加@EnableCaching

4.3 测试

从数据库10ms+，生产中会走网络通信会更长。
从Caffeine平均4ms