【redis】5.spring boot项目中，直接在spring data jpa的Repository层使用redis +redis注解@Cacheable直接在Repository层使用，报错问题处理Null key returned for cache operation

package com.agen.myagen.repository;


import com.agen.myagen.entity.XxAdmin;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.data.jpa.repository.JpaRepository;


/**
 * admin持久化层
 *
 * @author SXD
 * @date 2017/12/26
 */
public interface AdminRepository extends JpaRepository<XxAdmin,Integer> {

    /**
     * 查找机构信息
     * 并缓存到redis，键为id  值为XxAdmin
     * @param adminId
     * @return
     */
    @Cacheable(value="admins", key="#adminId")
    @Override
    XxAdmin findOne(Integer adminId);
}

package com.agen.controller;


import com.agen.myagen.entity.XxAdmin;
import com.agen.myagen.repository.AdminRepository;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.annotation.Resource;


@Controller
public class MainController {

    @Resource
    private AdminRepository adminRepository;

    @RequestMapping("index")
    public String getOrder(String adminId){
        Integer adminID = Integer.parseInt(adminId);
        XxAdmin admin = adminRepository.findOne(adminID);
        return  null;
    }


}

/**
     * 生成key的策略【自定义第三种】
     * 使用范围：仅适用于选取第一个参数做键的情况
     * 由于reposotory上不能直接使用spel表达式作key，故而采用key的生成策略的方式来替换
     *
     * 使用时在注解@Cacheable(value = "admins",keyGenerator = "firstParamKeyGenerator")中指定
     * @return
     */
    @Bean(name = "firstParamKeyGenerator")
    public KeyGenerator firstParamKeyGenerator(){
        return new KeyGenerator() {
            @Override
            public Object generate(Object target, Method method, Object... params) {
                StringBuilder sb = new StringBuilder();
                sb.append(params[0].toString());
                return sb.toString();
            }
        };
    }

public interface AdminRepository extends JpaRepository<XxAdmin,Integer> {

    /**
     * 查找机构信息
     * 并缓存到redis，键为id  值为XxAdmin
     * @param adminId
     * @return
     */
    @Cacheable(value="admins", keyGenerator = "firstParamKeyGenerator")
    @Override
    XxAdmin findOne(Integer adminId);
}

package com.agen.myagen.repository;


import com.agen.myagen.entity.XxAdmin;
import org.springframework.cache.annotation.CacheConfig;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.data.jpa.repository.JpaRepository;


/**
 * admin持久化层
 *
 * @author SXD
 * @date 2017/12/26
 */
@CacheConfig(cacheNames = "admins")
public interface AdminRepository extends JpaRepository<XxAdmin,Integer> {

    /**
     * 查找机构信息
     * 并缓存到redis，键为id  值为XxAdmin
     * @param adminId
     * @return
     */
    @Cacheable(keyGenerator = "firstParamKeyGenerator")
    @Override
    XxAdmin findOne(Integer adminId);
}