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打造redis缓存组件

news 来源：原创 2024/9/20 9:28:07

使用热插拔aop+反射+redis自定义注解+spring EL表达式打造redis缓存组件,优雅重构缓存代码

redis配置

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;@Configuration
@EnableAspectJAutoProxy //V2  开启AOP自动代理
public class RedisConfig
{/*** @param lettuceConnectionFactory* @return** redis序列化的工具配置类，下面这个请一定开启配置* 127.0.0.1:6379> keys ** 1) "ord:102"  序列化过* 2) "\xac\xed\x00\x05t\x00\aord:102"   野生，没有序列化过*/@Beanpublic RedisTemplate<String, Object> redisTemplate(LettuceConnectionFactory lettuceConnectionFactory){RedisTemplate<String,Object> redisTemplate = new RedisTemplate<>();redisTemplate.setConnectionFactory(lettuceConnectionFactory);//设置key序列化方式stringredisTemplate.setKeySerializer(new StringRedisSerializer());//设置value的序列化方式jsonredisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());redisTemplate.setHashKeySerializer(new StringRedisSerializer());redisTemplate.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());redisTemplate.afterPropertiesSet();return redisTemplate;}
}

自定义注解

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MyRedisCache     //@EnableAspectJAutoProxy //启AOP自动代理
{//约等于键的前缀prefix,String keyPrefix();//SpringEL表达式，解析占位符对应的匹配value值String matchValue();
}

AOP

import jakarta.annotation.Resource;
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.core.DefaultParameterNameDiscoverer;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.stereotype.Component;
import org.aspectj.lang.reflect.MethodSignature;import java.lang.reflect.Method;
import java.util.Objects;@Component
@Aspect
public class MyRedisCacheAspect
{@Resourceprivate RedisTemplate redisTemplate;//配置织入点@Pointcut("@annotation(com.atguigu.interview2.annotations.MyRedisCache)")public void cachePointCut(){}@Around("cachePointCut()")public Object doCache(ProceedingJoinPoint joinPoint){Object result = null;/***     @MyRedisCache(keyPrefix = "user",matchValue = "#id")*     public User getUserById(Integer id)*     {*         return userMapper.selectByPrimaryKey(id);*     }*/try{//1 获得重载后的方法名MethodSignature signature = (MethodSignature) joinPoint.getSignature();Method method = signature.getMethod();//2 确定方法名后获得该方法上面配置的注解标签MyRedisCacheMyRedisCache myRedisCacheAnnotation = method.getAnnotation(MyRedisCache.class);//3 拿到了MyRedisCache这个注解标签，获得该注解上面配置的参数进行封装和调用String keyPrefix = myRedisCacheAnnotation.keyPrefix();String matchValueSpringEL = myRedisCacheAnnotation.matchValue();//4 SpringEL 解析器ExpressionParser parser = new SpelExpressionParser();Expression expression = parser.parseExpression(matchValueSpringEL);//#idEvaluationContext context = new StandardEvaluationContext();//5 获得方法里面的形参个数Object[] args = joinPoint.getArgs();DefaultParameterNameDiscoverer discoverer = new DefaultParameterNameDiscoverer();String[] parameterNames = discoverer.getParameterNames(method);for (int i = 0; i < parameterNames.length; i++){System.out.println("获得方法里参数名和值: "+parameterNames[i] + "\t" + args[i].toString());context.setVariable(parameterNames[i], args[i].toString());}//6 通过上述，拼接redis的最终key形式String key = keyPrefix + ":" + expression.getValue(context).toString();System.out.println("------拼接redis的最终key形式: " + key);//7 先去redis里面查询看有没有result = redisTemplate.opsForValue().get(key);if (result != null){System.out.println("------redis里面有，我直接返回结果不再打扰mysql: " + result);return result;}//8 redis里面没有，去找msyql查询或叫进行后续业务逻辑//-------aop精华部分,才去找findUserById方法干活//userMapper.selectByPrimaryKey(id);result = joinPoint.proceed();//主业务逻辑查询mysql,放行放行放行//9 mysql步骤结束，还需要把结果存入redis一次，缓存补偿if (result != null){System.out.println("------redis里面无，还需要把结果存入redis一次，缓存补偿: " + result);redisTemplate.opsForValue().set(key, result);}} catch (Throwable throwable) {throwable.printStackTrace();}return result;}
}

测试

    /*** 会将返回值存进redis里，key生成规则需要程序员用SpEL表达式自己指定，value就是程序从mysql查出并返回的user* redis的key 等于  keyPrefix:matchValue*/@Override@MyRedisCache(keyPrefix = "user",matchValue = "#id")public User getUserById(Integer id){return userMapper.selectByPrimaryKey(id);}