如何编写对一个表操作的DAO和Entity

package com.tr.geda.evm.common.entity;

import java.util.Date;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;

@Entity
@Table(name = "USER_DETAILS")
public class UserDetails {
@Id
private String username;
private String password;
private String password_change;
private Date password_edit_date;
private Integer password_fails;
private String enabled;
private String permissioner;
private String user_type;
private String central_user;
@Transient
private boolean tdnUser = false;

public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getPassword_change() {
return password_change;
}
public void setPassword_change(String passwordChange) {
password_change = passwordChange;
}
public Date getPassword_edit_date() {
return password_edit_date;
}
public void setPassword_edit_date(Date passwordEditDate) {
password_edit_date = passwordEditDate;
}
public Integer getPassword_fails() {
return password_fails;
}
public void setPassword_fails(Integer passwordFails) {
password_fails = passwordFails;
}

public String getEnabled() {
return enabled;
}
public void setEnabled(String enabled) {
this.enabled = enabled;
}
public String getPermissioner() {
return permissioner;
}
public void setPermissioner(String permissioner) {
this.permissioner = permissioner;
}
public String getUser_type() {
return user_type;
}
public void setUser_type(String userType) {
user_type = userType;
}
public String getCentral_user() {
return central_user;
}
public void setCentral_user(String centralUser) {
central_user = centralUser;
}
public boolean isTdnUser() {
return tdnUser;
}
public void setTdnUser(boolean tdnUser) {
this.tdnUser = tdnUser;
}

}

package com.tr.geda.evm.dao.hibernate;

import java.util.List;

import org.hibernate.Query;
import org.springframework.context.annotation.Scope;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import org.springframework.stereotype.Repository;

import com.tr.geda.evm.common.entity.UserDetails;

@Repository
@Scope("singleton")
public class LoginDao extends HibernateDaoSupport {
public String getDBName() {
String sql = "select name from v$database";
Query query = getSession().createSQLQuery(sql);
return query.list().get(0).toString();
}

public String getHostName() {
String sql = "select host_name from v$instance";
Query query = getSession().createSQLQuery(sql);
return query.list().get(0).toString();
}

public UserDetails getUserByName(String user) {
UserDetails userDetail = null;
String hql = "select a from UserDetails a where a.username = ?";
List list = this.getHibernateTemplate().find(hql, user);
if(list == null || list.size() == 0)
{
return null;
}
return (UserDetails)list.get(0);

}

}