JavaWeb踩坑记录

1. org.apache.ibatis.binding.BindingException: Parameter 'XXXX' not found. 或 There is no getter for property named ‘XXX‘ in ‘class XXX

   • 原因分析（首先这个问题在 Dao 层）
     1. 检查 SQL 语句，#{}中的内容是否存在拼写错误，或者与参数中@param注解中不一致的情况
     2. @param的使用错误，使用方法参考：MyBatis参数传递

2. Mapper method 'priv.dandelion.dao.BrandMapper.selectTotalCountByCondition attempted to return null from a method with a primitive return type (int).

   • 原因分析：

     1. 是未配置 导致数据库与需要使用的名称不一致，需要配置@ResultMap使其名称一致就可以了

     2. 第二种情况就是误配置，如selectTotalCount 无返回值类型 就不要使用 @ResultMap，使用resultType，二者都不用会报错

        <select id="selectTotalCountByCondition" resultType="java.lang.Integer">
            select count(*) from tb_brand
            <where>
                <if test="brand.brandName != null and brand.brandName != ''">
                    brandName like #{brand.brandName}
                </if>
                <if test="brand.companyName != null and brand.companyName != ''">
                    and companyName like #{brand.companyName}
                </if>
                <if test="brand.status != null">
                    and status = #{brand.status}
                </if>
            </where>
        </select>

3. Unknown column 'companyName' in 'where clause'

   • 原因分析：并没有按照resultMap进行解析，where 标签中的内容必须要和数据库中一致

     • 错误代码

       <!-- 条件查询 -->
       <select id="selectByPageAndCondition" resultMap="brandResultMap">
           select * from tb_brand
           <where>
               <if test="brand.brandName != null and brand.brandName != ''">
                   brandName like #{brand.brandName}
               </if>
               <if test="brand.companyName != null and brand.companyName != ''">
                   and companyName like #{brand.companyName}
               </if>
               <if test="brand.status != null">
                   and status = #{brand.status}
               </if>
           </where>
           limit #{begin}, #{pageSize}
       </select>

     • 更整后代码

       <!-- 条件查询 -->
       <select id="selectByPageAndCondition" resultMap="brandResultMap">
           select * from tb_brand
           <where>
               <if test="brand.brandName != null and brand.brandName != ''">
                   brand_name like #{brand.brandName}
               </if>
               <if test="brand.companyName != null and brand.companyName != ''">
                   and company_name like #{brand.companyName}
               </if>
               <if test="brand.status != null">
                   and status = #{brand.status}
               </if>
           </where>
           limit #{begin}, #{pageSize}
       </select>