自定义SpringAop+Reids注解实现缓存存储

今天药忘吃喽~ 2022-04-10 13:23 344阅读 0赞

> SpringAop

Spring作为沉淀了许久的框架，在开发上带给的便利性不言而喻，主要是IOC+AOP关于这这两者的介绍请自行百度。看了AOP的实现：XML实现和注解实现，个人比较倾向于注解实现，不用写过多的配置比较方便。

Redis一种缓存技术提供了丰富的数据结构，下面就利用SpringAop+Redis实现热数据查询时首先在Redis中查询，不存在时再去数据库中查询。

> 注解实现

package com.luckincoffee.annoation;
    
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /**
     * @description 注解
     * @author Kangshuai Zuo
     * @date 2019/1/5 14:54
     */
    
    @Target(ElementType.METHOD)
    @Retention(RetentionPolicy.RUNTIME)
    public @interface CheckFromRedisAnnotation {
    
        // Redis命名空间
        String domain() ;
    
        // Redis中的key
        String key();
    
    }

package com.luckincoffee.aspect;
    
    import com.luckincoffee.annoation.CheckFromRedisAnnotation;
    import org.aspectj.lang.JoinPoint;
    import org.aspectj.lang.ProceedingJoinPoint;
    import org.aspectj.lang.annotation.Around;
    import org.aspectj.lang.annotation.Aspect;
    import org.aspectj.lang.annotation.Pointcut;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.core.LocalVariableTableParameterNameDiscoverer;
    import org.springframework.data.redis.core.HashOperations;
    import org.springframework.data.redis.core.RedisTemplate;
    import org.springframework.stereotype.Component;
    
    import java.lang.annotation.Annotation;
    import java.lang.reflect.Method;
    import java.util.LinkedList;
    import java.util.List;
    
    /**
     * @description redis中查询切面
     * @author Kangshuai Zuo
     * @date 2019/1/5 14:54
     */
    @Aspect
    @Component
    public class CheckFromRedis {
    
        @Autowired
        private RedisTemplate redisTemplate;
    
        private static LocalVariableTableParameterNameDiscoverer parameterNameDiscover = new LocalVariableTableParameterNameDiscoverer();
    
        @Pointcut("@annotation(com.luckincoffee.annoation.CheckFromRedisAnnotation)")
        public void checkFromRedis(){}
    
        @Around(value = "checkFromRedis()")
        public Object getFromRedis(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
            Method method = getMethod(proceedingJoinPoint);
            if(method != null){
                List<CheckFromRedisAnnotation> checkFromRedisAnnotations = getCacheResultAnnotation(method);
                CheckFromRedisAnnotation checkFromRedisAnnotation = checkFromRedisAnnotations.get(0);
                String domain = checkFromRedisAnnotation.domain();
                String key = checkFromRedisAnnotation.key();
                Object keyValue = getValueByMethodParamName(proceedingJoinPoint,key);
                HashOperations<String, String, Object> hashOperations = redisTemplate.opsForHash();
                Object object = hashOperations.get(domain,keyValue);
                if(object != null){
                    return object;
                }
                return proceedingJoinPoint.proceed();
            }
            return proceedingJoinPoint.proceed();
        }
    
        /**
         * 获取方法上的CheckFromRedisAnnotation注解
         * @param method 方法
         */
        private List<CheckFromRedisAnnotation> getCacheResultAnnotation(Method method){
            Annotation[] annotations = method.getAnnotations();
            List<CheckFromRedisAnnotation> checkFromRedisAnnotations = new LinkedList<>();
            for(Annotation a : annotations){
                if(a instanceof CheckFromRedisAnnotation){
                    checkFromRedisAnnotations.add((CheckFromRedisAnnotation)a);
                }
            }
            return checkFromRedisAnnotations;
        }
    
        /**
         * 获取织入切点的方法
         * @param joinPoint 切点
         * @return Method
         */
        private Method getMethod(JoinPoint joinPoint){
            // 获取切点的方法
            String methodLongName = joinPoint.getSignature().toLongString();
            // 反射获取类的所有方法
            Method[] methods = joinPoint.getTarget().getClass().getMethods();
            Method thisMethod = null;
            for(Method method : methods){
                if(method.toString().equals(methodLongName)){
                    thisMethod = method;
                    break;
                }
            }
            return thisMethod;
        }
    
    
        /**
         * 通过方法上的参数获取参数值
         * @param joinPoint 切点
         * @param parameterName 参数名称
         * @return Object
         */
        private Object getValueByMethodParamName(JoinPoint joinPoint, Object parameterName){
            Method method = getMethod(joinPoint);
            if (method == null){
                return null;
            }
            String[] parameterNames = parameterNameDiscover.getParameterNames(method);
            Object[] args = joinPoint.getArgs();
            if(parameterNames != null && parameterName != null){
                int i;
                for(i=0; i<parameterNames.length; ++i){
                    if(parameterName.equals(parameterNames[i])){
                        return args[i];
                    }
                }
            }
            return null;
        }
    }

> 注解使用

/**
         * 获取商品
         * @param goodsId 商品ID
         * @return Goods
         */
        @Override
        @CheckFromRedisAnnotation(domain = "goods",key = "goodsId")
        public Goods getGoodsByGoodsId(String goodsId) {
            try{
                return goodsMapper.getByGoodsId(goodsId);
            }catch (Exception e){
                LOG.info("获取商品失败："+e);
                return null;
            }
        }

在方法上面加入注解@CheckFromRedisAnnotation(domain = "goods",key = "goodsId")，该注解在执行的时候会先去Redis中查询命名空间和主键分别为goods和goodsId的商品信息，商品中有会直接返回商品信息，没有查询到再去数据库中查询然后存入Redis。可以减轻数据库的压力提高查询性能，但是如果该商品的信息被删除或者被修改也一定要删除Redis中该商品的信息，否则会造成数据的不一致性。