public class SpelUtils {

    private static final SpelExpressionParser parser = new SpelExpressionParser();
    private static final DefaultParameterNameDiscoverer nameDiscoverer = new DefaultParameterNameDiscoverer();

    public static Object parseValue(String spel, Method method, Object[] args) {
    
        String[] parameterNames = nameDiscoverer.getParameterNames(method);
        if (parameterNames == null) {
            return null;
        }
        
        EvaluationContext context = new StandardEvaluationContext();
        for (int i = 0; i < args.length; i++) {
            context.setVariable(parameterNames[i], args[i]);
        }
        
        Expression expression = parser.parseExpression(spel);

        return expression.getValue(context);
    }

}

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface MyAnn {
    String keyExpression();
}


@Around("@annotation(config)")
public Object around(ProceedingJoinPoint joinPoint, MyAnn config) throws Throwable {
    MethodSignature signature = (MethodSignature) joinPoint.getSignature();
    Object value = SpelUtils.parseValue(config.keyExpression(), signature.getMethod(), joinPoint.getArgs());
    // ...
}

@MyAnn(keyExpression = "'abc' + #bar")
void foo(String bar) {
    // 如果入参bar="def"，则在aspect里拿到的value是"abcdef"
}