*簡單工廠模式是屬於建立型模式，又叫做靜態工廠方法（Static Factory Method）模式，但不屬於23種GOF設計模式之一。簡單工廠模式是由一個工廠物件決定創建出哪一種產品類的例項。簡單工廠模式是工廠模式家族中最簡單實用的模式，可以理解為是不同工廠模式的一個特殊實現。*
 **為了更好的理解，下面以一個簡單的計算器的實現來講解**

    //運算元的基類
using System;
namespace AssemblyCSharp
{
    public class Operation
    {
        private double _numberA = 0;
        private
 
 double _numberB = 0;

        public double NumberA
        {
            get{return _numberA;}
            set{_numberA = value;}
        }

        public double NumberB
        {
            get{return _numberB;}
            set{_numberB = value;}

        }

        public virtual double GetResult
 
()
        {
            double result = 0;
            return result;
        }
    }
}

然後是每個操作符類的

using System;
namespace AssemblyCSharp
{
    class OperationAdd:Operation
    {
        public override double GetResult ()
        {
            double result = 0;
            result = NumberA + NumberB;
            return
 
 result;
        }
    }
    class OperationSub:Operation
    {
        public override double GetResult ()
        {
            double result = 0;
            result = NumberA - NumberB;
            return result;
        }
    }
    class OperationMul:Operation
    {
        public override double GetResult ()
        {
            double result = 0;
            result = NumberA * NumberB;
            return result;
        }
    }
    class OperationDiv:Operation
    {
        public override double GetResult ()
        {
            double result = 0;
            if (NumberB == 0) {
                throw new Exception("除數不能為0");
            }
            result = NumberA / NumberB;
            return result;
        }
    }
}

簡單工廠類

using UnityEngine;
using AssemblyCSharp;
using System.Collections;

public class OperationFactory  {


    public static Operation createOperate(string operate)
    {
        Operation oper = null;
        switch (operate) {
        case"+":
                oper = new OperationAdd();
            break;
        case"-":
                oper = new OperationSub();
            break;
        case"*":
                oper = new OperationMul();
            break;
        case"/":
                oper = new OperationDiv();
            break;
        }

        return oper;



    }


}

客戶端程式碼

using System;
using UnityEngine;
namespace AssemblyCSharp
{
    public class Client :MonoBehaviour
    {
        void Start()
        {
            Operation oper;
            oper = OperationFactory.createOperate ("/");
            oper.NumberA = 1;
            oper.NumberB = 0;
            double result = oper.GetResult ();
            Debug.Log (result);
        }
    }
}