利用泛型和反射，将从数据库select出来的集合直接转换成对象

现在的版本是直接利用反射的，下一步将改编成利用快速反射

public static T ExcuteEntity<T>(SQLiteCommand cmd)
        {
            Type entityType = typeof(T);
            PropertyInfo[] fieldinfos = entityType.GetProperties();
            T entity = (T)Activator.CreateInstance(entityType);
            DbDataReader reader = null;
            if (conn == null || conn.Length == 0)
                throw new ArgumentNullException("connectionString");
            SQLiteConnection con = new SQLiteConnection(conn);
            SQLiteTransaction trans = null;
            PrepareCommand(cmd, con, ref trans, false, cmd.CommandType, cmd.CommandText);
            try
            {
                reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                reader.Read();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            foreach (PropertyInfo field in fieldinfos)
            {
                int col=reader.GetOrdinal(field.Name);
                if (col != -1)
                {
                    Type mytype = reader.GetFieldType(col);
                    entityType.GetProperty(field.Name).SetValue(entity, Convert.ChangeType(reader.GetValue(col), mytype), null);
                }
                else {
                    continue;
                }
            }
            return entity;
        }
 
        public static List<T> ExecuteCollection<T>(SQLiteCommand cmd) {
            List<T> result = new List<T>();
            Type entityType = typeof(T);
            PropertyInfo[] fieldinfos = entityType.GetProperties();
            DbDataReader reader = null;
            if (conn == null || conn.Length == 0)
                throw new ArgumentNullException("connectionString");
            SQLiteConnection con = new SQLiteConnection(conn);
            SQLiteTransaction trans = null;
            PrepareCommand(cmd, con, ref trans, false, cmd.CommandType, cmd.CommandText);
            try
            {
                reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            while (reader.Read()) {
                T entity = (T)Activator.CreateInstance(entityType);
                foreach (PropertyInfo field in fieldinfos)
                {
                    int col = reader.GetOrdinal(field.Name);
                    if (col != -1)
                    {
                        Type mytype = reader.GetFieldType(col);
                        entityType.GetProperty(field.Name).SetValue(entity, Convert.ChangeType(reader.GetValue(col), mytype), null);
                    }
                    else
                    {
                        continue;
                    }
                }
                result.Add(entity);
            }
            return result;
        }