MyBatis 参数类型为String

mybatis mapper.xml sql 

当parameterType为String时

任何参数都必须为_parameter

正确写法：

xml version="1.0" encoding="UTF-8" ?>
>
<mapper namespace="com.stu.mapper.UserMapper">

    <select id="logconfirm" parameterType="String" resultType="String">
        select password from user where username=#{_parameter}
    select>

mapper>

之前写的是

然后提示错误There is no getter of  'username' in java.lang.string

xml version="1.0" encoding="UTF-8" ?>
>
<mapper namespace="com.stu.mapper.UserMapper">

    <select id="logconfirm" parameterType="String" resultType="String">
        select password from user where username=#{username}
    select>

mapper>