分布式Redis锁

• 引入redisson和hutool工具包

			
			<dependency>
                <groupId>org.redissongroupId>
                <artifactId>redisson-spring-boot-starterartifactId>
                <version>3.12.5version>
            dependency>
            
            <dependency>
                <groupId>cn.hutoolgroupId>
                <artifactId>hutool-allartifactId>
                <version>5.7.13version>
            dependency>

• 定义注解

import java.lang.annotation.*;
import java.util.concurrent.TimeUnit;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RedisLock {

    /**
     * redis锁 名字
     */
    String lockName() default "";

    /**
     * redis锁 key 支持spel表达式
     */
    String key() default "";

    /**
     * 过期秒数,默认为5毫秒
     *
     * @return 轮询锁的时间
     */
    int expire() default 1000*60*5;

    /**
     * 超时时间单位
     *
     * @return 秒
     */
    TimeUnit timeUnit() default TimeUnit.MILLISECONDS;
}

• 实现aop切面

import cn.hutool.core.util.StrUtil;
import cn.xxx.common.annotation.RedisLock;
import cn.xxx.common.utils.SpelUtil;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;


@Aspect
@Component
public class RedisLockAspect {

    @Autowired
    private RedissonClient redissonClient;

    private static final String REDISSON_LOCK_PREFIX = "redisson_lock:";

    @Around("@annotation(redisLock)")
    public Object around(ProceedingJoinPoint joinPoint, RedisLock redisLock) throws Throwable {
        String spel = redisLock.key();
        String lockName = redisLock.lockName();

        RLock rLock = redissonClient.getLock(getRedisKey(joinPoint,lockName,spel));

        rLock.lock(redisLock.expire(),redisLock.timeUnit());

        Object result = null;
        try {
            //执行方法
            result = joinPoint.proceed();

        } finally {
            rLock.unlock();
        }
        return result;
    }

    /**
     * 将spel表达式转换为字符串
     * @param joinPoint 切点
     * @return redisKey
     */
    private String getRedisKey(ProceedingJoinPoint joinPoint,String lockName,String spel) {
        Signature signature = joinPoint.getSignature();
        MethodSignature methodSignature = (MethodSignature) signature;
        Method targetMethod = methodSignature.getMethod();
        Object target = joinPoint.getTarget();
        Object[] arguments = joinPoint.getArgs();
        return REDISSON_LOCK_PREFIX + lockName + StrUtil.COLON + SpelUtil.parse(target,spel, targetMethod, arguments);
    }

}

• spel解析工具类

import cn.hutool.core.util.ArrayUtil;
import cn.hutool.core.util.StrUtil;
import org.springframework.context.expression.MethodBasedEvaluationContext;
import org.springframework.core.LocalVariableTableParameterNameDiscoverer;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;

import java.lang.reflect.Method;

/**
 * @version 1.0
 * @description: 解析SPEL 表达式
 * @date 2022/12/12 10:04
 */
public class SpelUtil {

    /**
     * 支持 #p0 参数索引的表达式解析
     * @param rootObject 根对象,method 所在的对象
     * @param spel 表达式
     * @param method ，目标方法
     * @param args 方法入参
     * @return 解析后的字符串
     */
    public static String parse(Object rootObject, String spel, Method method, Object[] args) {
        if (StrUtil.isBlank(spel)) {
            return StrUtil.EMPTY;
        }
        //获取被拦截方法参数名列表(使用Spring支持类库)
        LocalVariableTableParameterNameDiscoverer u =
                new LocalVariableTableParameterNameDiscoverer();
        String[] paraNameArr = u.getParameterNames(method);
        if (ArrayUtil.isEmpty(paraNameArr)) {
            return spel;
        }
        //使用SPEL进行key的解析
        ExpressionParser parser = new SpelExpressionParser();
        //SPEL上下文
        StandardEvaluationContext context = new MethodBasedEvaluationContext(rootObject,method,args,u);
        //把方法参数放入SPEL上下文中
        for (int i = 0; i < paraNameArr.length; i++) {
            context.setVariable(paraNameArr[i], args[i]);
        }
        return parser.parseExpression(spel).getValue(context, String.class);
    }
}