ssh2整合后调用CRUD方法，findByUserid没有关问题，可findByUsername报错，没找出原因，希望能得到解答

public class CMSUser {    private Integer userid;    private String username;    private String password;        public CMSUser(){}    public CMSUser(String username, String password){        this.username = username;        this.password = password;    }        public Integer getUserid() {        return userid;    }        ....//以下省略get,set方法.

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">        <hibernate-mapping package="com.ailincms.bean">    <class name="CMSUser">        <id name="userid" type="java.lang.Integer">            <generator class="native" />        </id>        <property name="username" length="20" not-null="true" unique="true"/>        <property name="password" length="20" not-null="true" />    </class></hibernate-mapping>

@Service(value="cMSUserServiceBean") @Transactionalpublic class CMSUserServiceBean implements CMSUserService {    @Resource SessionFactory factory;    public void createCMSUser(CMSUser cmsuser) {        factory.getCurrentSession().persist(cmsuser);    }    public void updateCMSUser(CMSUser cmsuser) {        factory.getCurrentSession().merge(cmsuser);    }    public void deleteByUsername(String... usernames) {        for(String username : usernames){            factory.getCurrentSession().delete(factory.getCurrentSession().load(CMSUser.class, username));        }    }    public void deleteByUserid(Integer userid) {        factory.getCurrentSession().delete(factory.getCurrentSession().get(CMSUser.class, userid));    }        @Transactional(propagation=Propagation.NOT_SUPPORTED)    public CMSUser findByUsername(String username) {//return (CMSUser)factory.getCurrentSession().delete(factory.getCurrentSession().get(CMSUser.class, userid));        return (CMSUser)factory.getCurrentSession().createQuery("from CMSUser as user where user.username='"+username+"'");//两种方法都试了，都报错。    }        @Transactional(propagation=Propagation.NOT_SUPPORTED)    public CMSUser findByUserid(Integer userid) {        return (CMSUser)factory.getCurrentSession().get(CMSUser.class, userid);    }        @SuppressWarnings("unchecked")    @Transactional(propagation=Propagation.NOT_SUPPORTED)    public List<CMSUser> getAllCMSUser() {        return factory.getCurrentSession().createQuery("from CMSUser").list();    }    }

public class CMSUser_CRUD {        private static CMSUserService userService;    @BeforeClass    public static void setUpBeforeClass() throws Exception {        ApplicationContext act = new ClassPathXmlApplicationContext("beans.xml");        userService  = (CMSUserService)act.getBean("cMSUserServiceBean");    }    @Test    public void createCMSUser() {        userService.createCMSUser(new CMSUser("xql","linlin520"));    //执行成功，未报错。    }        @Test    public void findByUserid(){        CMSUser cmsUser = userService.findByUserid(1);        ////执行成功，未报错。        System.out.println(cmsUser.getPassword());    }        @Test    public void findByUsername(){        CMSUser cmsUser = (CMSUser) userService.findByUsername("xql");         System.out.println(cmsUser.getPassword());    }               //执行失败，报错。}