工厂方法模式(Factory Pattern)

工厂方法模式对简单工厂模式进行改进，从工厂类中抽象出来一个接口用于创建实际工厂类，其uml图如下所示：

具体实现如下：

    class Operation
    {
        private double _numberA = 0;
        private double _numberB = 0;

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

        public virtual double GetResult()
        {
            double result = 0;
            return result;
        }
    }
    interface IFactory
    {
        Operation CreatOperation();
    }
    class OperationAdd : IFactory
    {
        public Operation CreatOperation()
        {
            return new OperationAdd();
        }
        public override double GetResult()
        {
            double result = 0;
            result = NubmerA + NumberB;
            return result;
        }
    }
    class OperationSub : IFactory
    {
        public Operation CreatOperation()
        {
            return new OperationSub();
        }
        public override double GetResult()
        {
            double result = 0;
            result = NubmerA - NumberB;
            return result;
        }
    }

调用：

         

            IFactory operFactory = new OperationAdd();
            Operation oper = operFactory.CreatOperation();
            oper.NubmerA = 1;
            oper.NumberB = 4;
            oper.GetResult();