C#设计模式——（创建型-工厂方法设计模式）

public interface ICalculator   
{
    public double GetResult(double d1,double d2);
}
public class Add:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1+d2;
    }
}
public class Sub:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1-d2;
    }
}
public class Mul:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1*d2;
    }
}
public class Div:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1/d2;
    }
}

/******************************************
public class CalFactory
{
   public static ICalculator GetCalculator()
   {
   //现在是抽象依赖细节，应该是细节依赖抽象
   }
}
*******************************************/
//把创建对象这件事封装成抽象
public interface ICalFactory
{
   ICalculator GetCalculator();
}
public class AddFactory:ICalFactory//细节依赖抽象
{
   public ICalculator GetCalculator()
   {
      return new Add();
   }
}
public class SubFactory:ICalFactory
{
   public ICalculator GetCalculator()
   {
      return new Sub();
   }
}
public class MulFactory:ICalFactory
{
   public ICalculator GetCalculator()
   {
      return new Mul();
   }
}
public class DivFactory:ICalFactory
{
   public ICalculator GetCalculator()
   {
      return new Div();
   }
}

publci static void Main(string[]args)
{
    Console.WriteLine("请输入操作数1");
    double d1=Convert.Todouble(Console.ReadLine());
    Console.WriteLine("请输入操作数2");
    double d2=Convert.Todouble(Console.ReadLine());
    Console.WriteLine("请输入操作符");
    string oper=Console.ReadLine();
    ICalFactory calFac=null;
    switch(oper)
    {
    case"+":
        calFac=new AddFactory();
        break;
      case"-":
        calFac=new SubFactory();
        break;
      case"*":
        calFac=new MulFactory();
        break;
      case"/":
        calFac=new DivFactory();
        break;      
    }
    ICalculator cal=calFac.GetCalculator();
    double ret=cal.GetResult(d1,d2);
    Console.ReadKey();
}

public interface ICalculator   
{
    public double GetResult(double d1,double d2);
}
public class Add:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1+d2;
    }
}
public class Sub:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1-d2;
    }
}
public class Mul:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1*d2;
    }
}
public class Div:ICalculator 
{
    public double GetResult(double d1,double d2)
    {
        return d1/d2;
    }
}

//1.使用Attribute给代码贴狗皮膏药
public class OperToFactory:Attribute
{
    public string Oper{get;}//因为值是我们直接写好，贴到类上，不需要set方法来赋值
    public OperToFactory(string s)
    {
       this.Oper=s;
    }
}
//2，程序运行后，拿到这段关系，并且返回响应的对象
public class ReflectionFactory
{
   //根据用户输入（操作符），返回一个对象
   Dictionary<string,ICalFactory> dic=new Dictionary<string,ICalFactory> ();
   public ReflectionFactory()
   {
      //1。拿到当前运行的程序集
      Assembly assembly=Assembly.GetExecutingAssembly();
      //AddFactory SubFactory MulFactory DivFactory
      foreach(var item in assembly.GetTypes())
      {
         //item 是ICalFactory类型的类，且不是接口
         if(typeof(ICalFactory).IsAssignableFrom(item)&&!item.IsInterface)
         {
            OperToFactory otf=item.GetCustomAttribute<OperToFactory>();
            if(otf.Oper!=null)
            {
               //给键值对集合赋值
               dic[otf.Oper]=Activator.CreateInstance(item) as IcalFactory;
            }
         }
      }      
   }
   public ICalFactory GetFunc(string s)
   {
      if(dic.ContainsKey(s))
      {
         return dic[s];
      }   
      return null;   
   }   
}

public interface ICalFactory
{
   ICalculator GetCalculator();
}

[OperToFactory("+")]
public class AddFactory:ICalFactory//细节依赖抽象
{
   public ICalculator GetCalculator()
   {
      return new Add();
   }
}

[OperToFactory("-")]
public class SubFactory:ICalFactory
{
   public ICalculator GetCalculator()
   {
      return new Sub();
   }
}

[OperToFactory("*")]
public class MulFactory:ICalFactory
{
   public ICalculator GetCalculator()
   {
      return new Mul();
   }
}

[OperToFactory("/")]
public class DivFactory:ICalFactory
{
   public ICalculator GetCalculator()
   {
      return new Div();
   }
}

publci static void Main(string[]args)
{
    Console.WriteLine("请输入操作数1");
    double d1=Convert.Todouble(Console.ReadLine());
    Console.WriteLine("请输入操作数2");
    double d2=Convert.Todouble(Console.ReadLine());
    Console.WriteLine("请输入操作符");
    string oper=Console.ReadLine();
    ReflectionFactory reff=new ReflectionFactory ();
    IcalFactory calFac=reff.GetFunc(oper);
    Icalculator cal=calFac.GetCalculator();
    double ret=cal.GetResult(d1,d2);
    Console.WriteLine(ret);
    //ICalFactory calFac=null;
    /****************************
    switch(oper)
    {
    case"+":
        calFac=new AddFactory();
        break;
      case"-":
        calFac=new SubFactory();
        break;
      case"*":
        calFac=new MulFactory();
        break;
      case"/":
        calFac=new DivFactory();
        break;      
    }
    ****************************/
    //ICalculator cal=calFac.GetCalculator();
    //double ret=cal.GetResult(d1,d2);
    Console.ReadKey();
}