java自定义参数注解@Target(ElementType.PARAMETER)无效?

package com.xxx.common.util;



import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;



/**

 * FileName: NotBlank

 * Description:

 * Version: v1.0.0

 * Author: liutf

 * Date: 2017-02-08

 */



@Retention(RetentionPolicy.RUNTIME)

@Target(ElementType.PARAMETER)

public @interface NotBlank {



    String value() default "";



}

package com.xxx.service.impl;

import com.xxx.common.util.NotBlank;

import com.xxx.dao.ProductDefDAO;

import com.xxx.entity.ProductDefEntity;

import com.xxx.service.ProductDefService;

import lombok.extern.slf4j.Slf4j;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.cache.annotation.Cacheable;

import org.springframework.stereotype.Service;

import org.springframework.transaction.annotation.Transactional;

import static com.xxx.common.constant.RigConst.DATA_STATE.VALID;



  @Service

  @Transactional

  @Slf4j

  public class ProductDefServiceImpl implements ProductDefService{

   @Autowired

   private ProductDefDAO dao;

   @Override

   @Cacheable(value="exProdCache")

   public ProductDefEntity getProduct(@NotBlank String channel) {

       ProductDefEntity entity = dao.findByChannelAndState(channel, VALID);

       if (entity == null) {

           log.error("渠道产品为空:channel:{}",channel);

       }

       return entity;

   }

  }

package com.xxx.common.util;



import org.aspectj.lang.ProceedingJoinPoint;

import org.aspectj.lang.annotation.Around;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.reflect.MethodSignature;

import org.springframework.stereotype.Component;



import java.lang.reflect.Method;



/**

 * FileName: NotBlankAspectHandler

 * Description:

 * Version: v1.0.0

 * Author: liutf

 * Date: 2017-02-08

 */



@Component

@Aspect

public class NotBlankAspectHandler {



    @Around("@annotation(NotBlank)")

    public Object validateAround(ProceedingJoinPoint joinPoint) throws Throwable {

        boolean result = false;

        MethodSignature signature = (MethodSignature) joinPoint.getSignature();

        Method method = signature.getMethod();    //得到拦截的方法

        Object[] args = joinPoint.getArgs();        //方法的参数



        for (Object arg : args) {

            if (arg instanceof  String){

                Precondition.checkStringArgument((String) arg);

            }

        }



        System.out.println("校验完成..");



        return joinPoint.proceed();

    }





}