熬夜的蟲子

  public class DBInstance
    {
        public void ExecuteNonQuery()
        {
        }

        public void ExecuteDataset()
        {
        }
       
    }
    public class SqlInstance : DBInstance
    {
        public void ExecuteNonQuery()
        {
            Console.WriteLine("this is a SqlInstance");
        }
    }
    public class OracleInstance : DBInstance
    {
        public void ExecuteNonQuery()
        {
            Console.WriteLine("this is a OracleInstance");
        }
    }
public interface Command
    {
        void execute();
    }

    public class SqlCommand : Command
    {
        SqlInstance sqlinstance;
        public SqlCommand(SqlInstance sqlins)
        {
            this.sqlinstance = sqlins;
        }
        public void execute()
        {
            sqlinstance.ExecuteNonQuery();
        }
    }

    public class OracleCommand : Command
    {
        OracleInstance Oracleinstance;
        public OracleCommand(OracleInstance Oracleins)
        {
            this.Oracleinstance = Oracleins;
        }
        public void execute()
        {
            Oracleinstance.ExecuteNonQuery();
        }
    }

    public class DBControl
    {
        Command[] commands;
        public DBControl()
        {
            commands = new Command[2];
        }
        public void setCommand(int index,Command comm)
        {
            commands[index] = comm;
        }
        public void control(int index)
        {
            commands[index].execute();
        }
    }

 DBControl dc = new DBControl();
            SqlInstance si = new SqlInstance();
            SqlCommand sc = new SqlCommand(si);
            OracleInstance oi = new OracleInstance();
            OracleCommand oc = new OracleCommand(oi);

            dc.setCommand(0, sc);
            dc.setCommand(1, oc);

            dc.control(0);
            dc.control(1);