工厂模式

简介：

              工厂模式有三种，分别是简单工厂、工厂方法、抽象工厂。

简单工厂	简单工厂模式的工厂类随着产品类的增加需要增加额外的代码，例如case或者if-else等。没有抽象工厂类，仅有产品抽象。简单工厂模式缺点，就是随着需求的变化我们要不停地修改工厂里面的方法的代码，需求变化越多，里面的case或者if-else等也越多，这样就会造成简单工厂的实现逻辑过于复杂。这样的修改也是不符合【开放关闭原则OCP】，对修改代码关闭，对增加代码开放。
工厂方法	工厂方法模式是解决单个对象的需求变化，即仅有一个抽象产品类，可以有多个继承抽象产品类和抽象工厂类。每个继承工厂类仅有一个继承产品类的实例。如果新增产品，需要新增继承产品抽象类、继承工厂抽象类。
抽象工厂	抽象工厂模式是结果对于多个对象的需求变化，即可有多个产品抽象类。每个继承工厂类有多个继承产品类的实例。如果新增产品，需要新增抽象工厂类、继承工厂抽象类、产品抽象类、继承产品抽象类。

 

介绍：

工厂方法模式结构

抽象工厂模式结构

 

使用：

1.简单工厂

    //工厂类
    public class Factory
    {
        public static IDraw GetDraw(string type)
        {
            IDraw draw = null;
            switch (type)
            {
                case "Square": draw = new SquareDraw(); break;
                case "Circle": draw = new CircleDraw(); break;
                default: break;
            }
            return draw;
        }
    }
    
    //抽象产品类
    public abstract class IDraw
    {
        public abstract void Draw();
    }

    //继承产品类
    public class SquareDraw : IDraw
    {
        public override void Draw()
        {
           //do something
        }
    }

    //继承产品类
    public class CircleDraw : IDraw
    {
        public override void Draw()
        {
           //do something
        }
    }

 //简单工厂调用
 IDraw draw = Factory.GetDraw("Square");
 raw.Draw();

 draw = Factory.GetDraw("Circle");
 draw.Draw();

 

2.工厂方法

    //抽象工厂类 
    public abstract class IFactory
    {
        public abstract IDraw GetDraw();
    }

    //继承工厂抽象类
    public class SquareFactory:IFactory
    {
        public override IDraw GetDraw()
        {
            IDraw draw = new SquareDraw();
            return draw;
        }
    }

    //继承工厂抽象类
    public class CircleFactory : IFactory
    {
        public override IDraw GetDraw()
        {
            IDraw draw = new CircleDraw();
            return draw;
        }
    }

    //产品抽象类
    public abstract class IDraw
    {
        public abstract void Draw();
    }

    //继承产品抽象类
    public class SquareDraw : IDraw
    {
        public override void Draw()
        {
           //do something
        }
    }

    //继承产品抽象类
    public class CircleDraw : IDraw
    {
        public override void Draw()
        {
           //do something
        }
    }

//工厂方法调用
IFactory fact = new SquareFactory();
IDraw draw = fact.GetDraw();
draw.Draw();

fact = new CircleFactory();
draw = fact.GetDraw();
draw.Draw();

 

 3.抽象工厂

    //抽象工厂类
    public abstract class IFactory
    {
        //产品的抽象方法
        public abstract IDraw GetDraw();
        public abstract IPrint GetPrint();
    }

    //继承工厂类
    public class SquareFactory : IFactory
    {
        //产品类的实例
        public override IDraw GetDraw()
        {
            IDraw draw = new SquareDraw();
            return draw;
        }

        //产品类的实例
        public override IPrint GetPrint()
        {
            IPrint print = new SquarePrint();
            return print;
        }
    }

    //继承工厂类
    public class CircleFactory : IFactory
    {
        public override IDraw GetDraw()
        {
            IDraw draw = new CircleDraw();
            return draw;
        }
        public override IPrint GetPrint()
        {
            IPrint print = new CirclePrint();
            return print;
        }
    }

    //抽象产品类
    public abstract class IDraw
    {
        public abstract void Draw();
    }

    //继承产品类
    public class SquareDraw : IDraw
    {
        public override void Draw()
        {
           //do something
        }
    }

    //继承产品类
    public class CircleDraw : IDraw
    {
        public override void Draw()
        {
           //do something
        }
    }

    //抽象产品类
    public abstract class IPrint
    {
        public abstract void Print();
    }

    //继承产品类
    public class SquarePrint : IPrint
    {
        public override void Print()
        {
           //do something
        }
    }

    //继承产品类
    public class CirclePrint : IPrint
    {
        public override void Print()
        {
           //do something
        }
    }

//抽象工厂调用
IFactory fact = new SquareFactory();
fact.GetDraw();
fact.GetPrint();
 
fact = new CircleFactory();
fact.GetDraw();
fact.GetPrint();