Mybatis There is no getter for property named in ‘class java.lang.String’

 <select id="getRiskMember" resultMap="BaseResultMap" parameterType="String">
        <include refid="selectMember"/>
        and safetylevel > 1
        and stauts = 1

        <if test="username != null">
            and username = #{username} 
        </if>
    </select>

改成

<select id="getRiskMember" resultMap="BaseResultMap" parameterType="String">
        <include refid="selectMember"/>
        and safetylevel > 1
        and stauts = 1

        <if test="_parameter != null">
            and username = #{username} 
        </if>
    </select>