当传入数据只有一个时mybatis中<if>判断会出现There is no getter for property named 'subjectId' in 'class java.lang.Integer

用"_parameter"代替当前参数

正确：

<select id="selectSubjectByPId"  parameterType="java.lang.Integer" resultType="java.util.Map">
        select subjectId,subjectName 
        from ts_subject 
        where subjectParentId= 0 
        <if test="_parameter != null">
            and subjectId = #{_parameter,jdbcType=INTEGER}
        </if>
</select>

错误：

<select id="selectSubjectByPId"  parameterType="java.lang.Integer" resultType="java.util.Map">
        select subjectId,subjectName 
        from ts_subject 
        where subjectParentId= 0 
        <if test="subjectId != null">
            and subjectId = #{subjectId,jdbcType=INTEGER}
        </if>
</select>

这时候就会出现异常.

There is no getter for property named 'subjectId' in 'class java.lang.Intege