温故而知新:设计模式之桥接模式(Bridge)

     public   abstract   class  DataExporter
    {
         protected  OS os; // 关键：这里放一个平台的抽象类，以对象组合的方式实现依赖倒置

         public   abstract   void  Export();

         public  DataExporter(OS os)
        {
             this .os  =  os;
        }
    }

     public   abstract   class  OS
    {
         public   abstract   void  WriteToTxt();

         public   abstract   void  WriteToDB();

         public   abstract   void  WriteToXML();
    }

     public    class  WinOS : OS
    {
         public   override   void  WriteToTxt()
        {
            Console.WriteLine( " Windows系统上写txt文件的实现! " );
        }

         public   override   void  WriteToDB()
        {
            Console.WriteLine( " Windows系统上导入数据库的实现! " );
        }

         public   override   void  WriteToXML()
        {
            Console.WriteLine( " Windows系统上写Xml文件的实现! " );
        }
    }

     public    class  LinuxOS : OS 
    {
         public   override   void  WriteToTxt()
        {
            Console.WriteLine( " Linux系统上写txt文件的实现! " );
        }

         public   override   void  WriteToDB()
        {
            Console.WriteLine( " Linux系统上导入数据库的实现! " );
        }

         public   override   void  WriteToXML()
        {
            Console.WriteLine( " Linux系统上写Xml文件的实现! " );
        }
    }

     public    class  MacOS : OS
    {
         public   override   void  WriteToTxt()
        {
            Console.WriteLine( " MacOS系统上写txt文件的实现! " );
        }

         public   override   void  WriteToDB()
        {
            Console.WriteLine( " MacOS系统上导入数据库的实现! " );
        }

         public   override   void  WriteToXML()
        {
            Console.WriteLine( " MacOS系统上写Xml文件的实现! " );
        }
    }

     public    class  FreeBsdOS : OS
    {
         public   override   void  WriteToTxt()
        {
            Console.WriteLine( " FreeBsd系统上写txt文件的实现! " );
        }

         public   override   void  WriteToDB()
        {
            Console.WriteLine( " FreeBsd系统上导入数据库的实现! " );
        }

         public   override   void  WriteToXML()
        {
            Console.WriteLine( " FreeBsd系统上写Xml文件的实现! " );
        }
    }

     public   class  TxtDataExporter : DataExporter
    {
         public  TxtDataExporter(OS os)
            :  base (os)
        {

        }

         public   override   void  Export()
        {
            os.WriteToTxt();
        }
    }

     public   class  XmlDataExporter : DataExporter
    {
         public  XmlDataExporter(OS os)
            :  base (os)
        {

        }

         public   override   void  Export()
        {
            os.WriteToXML();
        }
    }

     public   class  DatabaseDataExporter : DataExporter
    {
         public  DatabaseDataExporter(OS os)
            :  base (os)
        {

        }

         public   override   void  Export()
        {
            os.WriteToDB();
        }
    }

     class  Program
    {
         static   void  Main( string [] args)
        {
            DataExporter export  =   new  TxtDataExporter( new  WinOS()); // 这样就得到了一个Windows平台上的txt格式导出实例
            export.Export();

            Console.ReadKey();
        }
    }