关于spring的自定义缓存注解分析

为什么要自定义缓存注解？

Spring Cache本身提供@Cacheable、@CacheEvict、@CachePut等缓存注解，为什么还要自定义缓存注解呢？

@Cacheabe不能设置缓存时间，导致生成的缓存始终在redis中，当然这一点可以通过修改RedisCacheManager的配置来设置缓存时间：

@Bean
public RedisCacheManager redisCacheManager(RedisConnectionFactory redisConnectionFactory) {
RedisCacheConfiguration redisCacheConfiguration = getRedisCacheConfiguration();
RedisCacheManager cacheManager = RedisCacheManager
.builder(RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory))
.cacheDefaults(redisCacheConfiguration)
.build();
return cacheManager;
}
private RedisCacheConfiguration getRedisCacheConfiguration() {
Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<>(Object.class);
ObjectMapper om = new ObjectMapper();
om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
om.activateDefaultTyping(LaissezFaireSubTypeValidator.instance, ObjectMapper.DefaultTyping.NON_FINAL, JsonTypeInfo.As.WRAPPER_ARRAY);
jackson2JsonRedisSerializer.setObjectMapper(om);
RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig();
redisCacheConfiguration = redisCacheConfiguration.serializeValuesWith(
RedisSerializationContext
.SerializationPair
.fromSerializer(jackson2JsonRedisSerializer)
).entryTtl(Duration.ofDays(7)); // 设置全局key的有效事件为7天
return redisCacheConfiguration;
}

不过这个设置时全局的，所有的key的失效时间都一样，要想实现不同的key不同的失效时间，还得自定义缓存注解。

自定义缓存注解

Cached

类似Spring Cache的@Cacheable。

package com.morris.spring.custom.cache.annotation;
import org.springframework.core.annotation.AliasFor;
import java.lang.annotation.*;
import java.util.concurrent.TimeUnit;
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Cached {
@AliasFor("cacheName")
String value() default "";
@AliasFor("value")
String cacheName() default "";
int expire() default 0;
TimeUnit expireUnit() default TimeUnit.SECONDS;
String key();
String condition() default "";
String unless() default "";
boolean sync() default false;
}

CacheUpdate

类似于Spring Cache的@CachePut。

package com.morris.spring.custom.cache.annotation;
import org.springframework.core.annotation.AliasFor;
import java.lang.annotation.*;
import java.util.concurrent.TimeUnit;
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface CacheUpdate {
@AliasFor("cacheName")
String value() default "";
@AliasFor("value")
String cacheName() default "";
int expire() default 0;
TimeUnit expireUnit() default TimeUnit.SECONDS;
String key();
String condition() default "";
String unless() default "";
}

CacheInvalidate

类似于Spring Cache的@CacheEvict。

package com.morris.spring.custom.cache.annotation;
import org.springframework.core.annotation.AliasFor;
import java.lang.annotation.*;
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface CacheInvalidate {
@AliasFor("cacheName")
String value() default "";
@AliasFor("value")
String cacheName() default "";
String key();
String condition() default "";
String unless() default "";
}

CachedAspect

@Cached注解的切面实现。

package com.morris.spring.custom.cache.annotation;
import com.morris.spring.custom.cache.Level2Cache;
import com.morris.spring.custom.cache.Level2CacheManage;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.cache.Cache;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.expression.EvaluationContext;
import javax.annotation.Resource;
import java.util.Objects;
@Configuration
@Aspect
@EnableAspectJAutoProxy // 开启AOP
public class CachedAspect {
@Resource
private Level2CacheManage cacheManager;
@Around(value = "@annotation(cached)")
public Object around(ProceedingJoinPoint joinPoint, Cached cached) throws Throwable {
Level2Cache cache = cacheManager.getCache(cached.cacheName());
ExpressionEvaluator evaluator = new ExpressionEvaluator();
EvaluationContext context = evaluator.createEvaluationContext(joinPoint);
Object key = evaluator.key(cached.key(), context);
if(cached.sync()) {
//
return cache.get(key, () -> {
try {
return joinPoint.proceed();
} catch (Throwable e) {
e.printStackTrace();
return null;
}
});
}
// 先查缓存
Cache.ValueWrapper valueWrapper = cache.get(key);
if (Objects.nonNull(valueWrapper)) {
return valueWrapper.get();
}
Object result = joinPoint.proceed();
context.setVariable("result", result);
Boolean condition = evaluator.condition(cached.condition(), context);
Boolean unless = evaluator.unless(cached.unless(), context);
if (condition && !unless) {
if (cached.expire() > 0) {
cache.put(key, result, cached.expire(), cached.expireUnit());
} else {
cache.put(key, result);
}
}
return result;
}
}

CacheUpdateAspect

@CacheUpdate注解的切面实现类。

package com.morris.spring.custom.cache.annotation;
import com.morris.spring.custom.cache.Level2Cache;
import com.morris.spring.custom.cache.Level2CacheManage;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.context.annotation.Configuration;
import org.springframework.expression.EvaluationContext;
import javax.annotation.Resource;
@Configuration
@Aspect
public class CacheUpdateAspect {
@Resource
private Level2CacheManage cacheManager;
@Around(value = "@annotation(cacheUpdate)")
public Object around(ProceedingJoinPoint joinPoint, CacheUpdate cacheUpdate) throws Throwable {
Level2Cache cache = cacheManager.getCache(cacheUpdate.cacheName());
ExpressionEvaluator evaluator = new ExpressionEvaluator();
EvaluationContext context = evaluator.createEvaluationContext(joinPoint);
Object key = evaluator.key(cacheUpdate.key(), context);
Object result = joinPoint.proceed();
context.setVariable("result", result);
Boolean condition = evaluator.condition(cacheUpdate.condition(), context);
Boolean unless = evaluator.unless(cacheUpdate.unless(), context);
if (condition && !unless) {
if (cacheUpdate.expire() > 0) {
cache.put(key, result, cacheUpdate.expire(), cacheUpdate.expireUnit());
} else {
cache.put(key, result);
}
}
return result;
}
}

CacheInvalidateAspect

@CacheInvalidate注解的切面实现类。

package com.morris.spring.custom.cache.annotation;
import com.morris.spring.custom.cache.Level2Cache;
import com.morris.spring.custom.cache.Level2CacheManage;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.context.annotation.Configuration;
import org.springframework.expression.EvaluationContext;
import javax.annotation.Resource;
@Configuration
@Aspect
public class CacheInvalidateAspect {
@Resource
private Level2CacheManage cacheManager;
@Around(value = "@annotation(cacheInvalidate)")
public Object around(ProceedingJoinPoint joinPoint, CacheInvalidate cacheInvalidate) throws Throwable {
Level2Cache cache = cacheManager.getCache(cacheInvalidate.cacheName());
ExpressionEvaluator evaluator = new ExpressionEvaluator();
EvaluationContext context = evaluator.createEvaluationContext(joinPoint);
Object key = evaluator.key(cacheInvalidate.key(), context);
Object result = joinPoint.proceed();
context.setVariable("result", result);
Boolean condition = evaluator.condition(cacheInvalidate.condition(), context);
Boolean unless = evaluator.unless(cacheInvalidate.unless(), context);
if (condition && !unless) {
cache.evict(key);
}
return result;
}
}

ExpressionEvaluator

ExpressionEvaluator主要用于解析注解中key、condition、unless属性中的表达式。

package com.morris.spring.custom.cache.annotation;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.aop.support.AopUtils;
import org.springframework.context.expression.MethodBasedEvaluationContext;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.util.StringUtils;
import java.lang.reflect.Method;
public class ExpressionEvaluator {
private final SpelExpressionParser parser = new SpelExpressionParser();
public EvaluationContext createEvaluationContext(ProceedingJoinPoint joinPoint) {
MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();
Method specificMethod = AopUtils.getMostSpecificMethod(methodSignature.getMethod(), joinPoint.getTarget().getClass());
MethodBasedEvaluationContext context = new MethodBasedEvaluationContext(joinPoint.getTarget(),
specificMethod, joinPoint.getArgs(), new DefaultParameterNameDiscoverer());
return context;
}
public Object key(String keyExpression, EvaluationContext evalContext) {
Expression expression = parser.parseExpression(keyExpression);
return expression.getValue(evalContext);
}
public boolean condition(String conditionExpression, EvaluationContext evalContext) {
if(!StringUtils.hasText(conditionExpression)) {
return true;
}
Expression expression = parser.parseExpression(conditionExpression);
return (Boolean.TRUE.equals(expression.getValue(evalContext, Boolean.class)));
}
public boolean unless(String unlessExpression, EvaluationContext evalContext) {
if(StringUtils.hasText(unlessExpression)) {
return false;
}
Expression expression = parser.parseExpression(unlessExpression);
return (Boolean.TRUE.equals(expression.getValue(evalContext, Boolean.class)));
}
}

总结

• 自定义缓存注解使用了AOP的通知功能，所以需要开启AOP，需要在配置类上加上@EnableAspectJAutoProxy注解。

• 改进：可使用类似@EnableCache注解导入一个入口类，不再需要多个切面，多个注解的处理逻辑放在一起，参考Spring Cache。

• 扩展：解析表达式可使用缓存，加快解析速度；方法上面支持多个@Cached注解。

来源：https://morris131.blog.csdn.net/article/details/124426114