mybatis There is no getter for property named 'xx' in 'class java.lang.String

用mybatis查询时，传入一个字符串传参数，且进行判断时，会报

There is no getter for property named 'projectId' in 'class java.lang.String  

错误写法：

    <select id="queryAll" parameterType="String" resultType="ComDTO">
        select
            userId,openid,wxName,wxImg,name,sex,age,telNum,checkCode,playNum,otherNum,
            user.projectId projectId,projectName,projectSimName,projectNum,user.createTime createTime
        from com_user user, com_project project 
        <where>
            user.projectId = project.projectId
            <if test="projectId != null and projectId !=''">
                and user.projectId=#{projectId}
            </if>
        </where>
        order by userId desc
    </select>

  需要修改成：
  

    <select id="queryAll" parameterType="String" resultType="ComDTO">
        select
            userId,openid,wxName,wxImg,name,sex,age,telNum,checkCode,playNum,otherNum,
            user.projectId projectId,projectName,projectSimName,projectNum,user.createTime createTime
        from com_user user, com_project project 
        <where>
            user.projectId = project.projectId
            <if test="_parameter != null and _parameter !=''">
                and user.projectId=#{_parameter}
            </if>
        </where>
        order by userId desc
    </select>

  不管你的参数是什么，都要改成"_parameter"