研究半天没有找出来问题出在哪里

mapper.xml

<select id="selectlike" resultType="com.rj.entity.Student">
    select * from student WHERE sname LIKE '${sname}%'
</select>
<select id="selectwhere" resultType="com.rj.entity.Student">
    select * from  student
    <where>
        <if test="stu.sname !=null and stu.sname !=''">
            sname LIKE '${stu.sname}%'
        </if>
        <if test="stu.sno !=null and stu.sno !=''">
            AND sno LIKE '${stu.sno}%'
        </if>
    </where>
</select>

dao

public  List<Student> selectwhere(@Param("stu") Student stu);

service

public  List<Student> selectwhere(Student stu) throws IOException;

serviceimpl

public List<Student> selectwhere(Student stu) throws IOException {
    SqlSession session = MyBatisUtil.getSqlSession();
    //创建dao层对象 代理模式（反射）
    IStudentDao dao=session.getMapper(IStudentDao.class);
    //调用dao层提供的方法
    List<Student> list =dao.selectwhere(stu);
    //关闭session
    MyBatisUtil.close();
    return list;
}

testmain

//调用service
IStudentService service = new IStudentServiceImpl();
//List<Student> students = service.selectAllList();
Student student=new Student();
student.setSname("王");
student.setSno("19");
//模糊查询
// List<Student> students=service.selectlike(student);
//多条件查询
List<Student> students=service.selectwhere(student);
//打印输出
System.out.println(students);

总是报这个错是怎么会是呢

Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.apache.ibatis.builder.BuilderException: Error evaluating expression 'stu.sno !=null and stu.sno !='''. Cause: org.apache.ibatis.ognl.NoSuchPropertyException: com.rj.entity.Student.sno
### Cause: org.apache.ibatis.builder.BuilderException: Error evaluating expression 'stu.sno !=null and stu.sno !='''. Cause: org.apache.ibatis.ognl.NoSuchPropertyException: com.rj.entity.Student.sno

org.apache.ibatis.ognl.NoSuchPropertyException: com.rj.entity.Student.sno，看看Student对象的sno属性有没有get方法