I have a abstract class User and 3 classes who extend from this class (Admin, Modurator, Lector).
我有一个抽象类User和3个类，它们从这个类扩展（Admin，Modurator，Lector）。
In my db I have a table User with the data needed (UserName / Password / Security_lvl).
在我的数据库中，我有一个用户表，其中包含所需的数据（UserName / Password / Security_lvl）。
The connection to the database for User I do with DAO.
用户的数据库连接我用DAO。
public class MysqlUserDao implements UserDao {
//
private static MysqlUserDao instance;
//
public static MysqlUserDao getInstance() {
if (instance == null)
instance = new MysqlUserDao();
return instance;
}
public void create(User user) {
try {
c = MySqlDAOFactory.getInstance().getConnection();
//
String sql = "insert into user values (?,?,?)";
//
prest = c.prepareStatement(sql);
//
prest.setString(1, user.getUserName());
prest.setString(2, user.getPassword());
prest.setInt(3, user.getRole().returnSecurityLevel());
//
prest.executeUpdate();
//
} catch (SQLException e) {
JdbcLogging.info("error item" + " :"
+ e);
} finally {
MySqlConnectionFactory.getInstance().closeResultSet(rs);
MySqlConnectionFactory.getInstance().closeStatement(prest);
MySqlConnectionFactory.getInstance().closeConnection(c);
}
}
}
}
In java depending on the user-type I make the specific Admin, Modurator or Lector objects so I can use their specific methods.
在java中，根据用户类型我制作特定的Admin，Modurator或Lector对象，以便我可以使用他们的特定方法。
Now the problem I have, is that I need a User for this DAO. But User is abstract and I do not make any User objects. I can make three different DAO's for each of the other classes but they would just do the same. Is there a clean way to do this ... .
现在我遇到的问题是，我需要这个DAO的用户。但是User是抽象的，我不做任何User对象。我可以为其他每个类制作三个不同的DAO，但他们也会这样做。有没有一个干净的方法来做到这一点......
Their maybe is a simple solution but I'm just not seeing it.
他们可能是一个简单的解决方案，但我只是没有看到它。
1 个解决方案
#1
3
You can pass Admin, Moderator or Lector instances as parameters to your create method. Polymorphism in Java allows that kind of behaviour.
您可以将Admin，Moderator或Lector实例作为参数传递给create方法。 Java中的多态性允许这种行为。
#1
3
You can pass Admin, Moderator or Lector instances as parameters to your create method. Polymorphism in Java allows that kind of behaviour.
您可以将Admin，Moderator或Lector实例作为参数传递给create方法。 Java中的多态性允许这种行为。