C#设计模式之简单工厂篇

    看明白了吗？好了，我们该让尊敬的、永远高贵的客户出场了，只有他，唯有他才有决定用哪种数据库的最高权限，你看，他这样用：

public class Client

    {

        public static void Main()

        {

            //Get the database information from Web.Config.

            string DBType = ConfigurationSettings.AppSettings["DBType"];

            string DBConnectString = ConfigurationSettings.AppSettings["DBConn"];

            IDatabase DB = Factory.SelectDatabase(DBType);

            //Connect the selected database.

            if(DB.Connect(DBConnectString)==false)

            {

                Console.WriteLine("The database {0} can@#t be connected.",DBType);

                return;

            }

            //Open database.

            if(DB.Open()==false)

            {

                Console.WriteLine("The database {0} can@#t be opened, the connect string is {1}.",DBType,DBConnectString);

                return;

            }

            //Execute SQL Command.

            string SQL = "update Order set price = price * 0.07 where productID = @#002@#";

            if(DB.Command(SQL))

            {

                //Do something...

            }

            else

            {

                Console.WriteLine("The Operator is not success. SQL statament is {0}",SQL);

                DB.Close();

                return;

            }

            DB.Close();

        }

    }

    好了，工程峻工了，你们明白了没有？

    思考题：简单工厂的应用场合和局限性？

    作业题：假如要开发一个多媒体播放器，既能用Window MediaPlayer播放，又能用RealPlayer播放，还能用QuickTime播放，具体用什么播放器，由客户选择，请你画出UML图并写出代码。

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