Mybatis 的问题，我按照原本的格式写一个操作为什么原先的能成功，而我的不管怎样都会失败呢？

这个项目 Dao 是单独一个项目，然后打成 jar 包添加到 maven。在后台项目里从 maven 引入的。 我想在 Dao 里加一个操作，但是就很简单的查询也会失败。 模仿的样例：
AppUserMapper.java

public interface AppUserMapper {
    //......
    AppUser selectByPrimaryKey(String id);
    //......
}

AppUserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="XXX.dao.AppUserMapper">
  <resultMap id="BaseResultMap" type="XXX.entity.AppUser">
    <!--实体类映射-->
  </resultMap>

  <sql id="Base_Column_List">
    <!--查询的值-->
  </sql>
  <!--省略-->
  <select id="selectByPrimaryKey" parameterType="java.lang.String" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from app_user
    where id = #{id,jdbcType=VARCHAR}
  </select>
  <!--省略-->
</mapper>

自己写的：
GoodsOff.java

package XXX.entity;

import java.io.Serializable;

public class GoodsOff implements Serializable {
    private int id;
    private String goodsId;
    private float off;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getGoodsId() {
        return goodsId;
    }

    public void setGoodsId(String goodsId) {
        this.goodsId = goodsId;
    }

    public float getOff() {
        return off;
    }

    public void setOff(float off) {
        this.off = off;
    }
}

GoodsOffMapper.java

package XXX.dao;

import XXX.entity.GoodsOff;

public interface GoodsOffMapper {
    GoodsOff selectByPrimaryKey(String goodsId);
}

GoodsOffMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="XXX.dao.GoodsOffMapper">
  <resultMap id="BaseResultMap" type="XXX.entity.GoodsOff">
    <id column="id" jdbcType="INTEGER" property="id" />
    <result column="goods_id" jdbcType="VARCHAR" property="goodsId" />
    <result column="off" jdbcType="FLOAT" property="off" />
  </resultMap>
  <select id="selectByPrimaryKey" parameterType="java.lang.String" resultMap="BaseResultMap">
    select
    *
    from hbmm_goodsoff
    where goods_id = #{goodsId,jdbcType=VARCHAR}
  </select>
</mapper>

我数据库里的表：

REATE TABLE `hbmm_goodsoff` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `goods_id` varchar(64) CHARACTER SET utf8mb4 DEFAULT NULL,
  `off` float DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=22 DEFAULT CHARSET=utf8;