设计模式：简单工厂模式和工厂方法模式的区别

来源：互联网发布：acs550变频器端口定义编辑：程序博客网时间：2024/06/05 15:25

简单工厂模式：本着高内聚低耦合的原则，将系统的逻辑部分和功能分开

例如简易计算器的实现代码

using System;using System.Collections.Generic;using System.Text;namespace Operation{    /// <summary>    /// 运算类    /// </summary>    public class Operation    {        private double _numberA = 0;        private double _numberB = 0;                /// <summary>        /// 数字A        /// </summary>        public double NumberA        {            get            {                return _numberA;            }            set            {                _numberA = value;            }        }        /// <summary>        /// 数字B        /// </summary>        public double NumberB        {            get            {                return _numberB;            }            set            {                _numberB = value;            }        }        /// <summary>        /// 得到运算结果        /// </summary>        /// <returns></returns>        public virtual double getResult()        {            double result = 0;             return result;        }           }    /// <summary>    /// 加法类    /// </summary>    class OperationAdd : Operation    {        public override double getResult()        {            double result = 0;             result = NumberA + NumberB;            return result;        }    }    /// <summary>    /// 减法类    /// </summary>    class OperationSub : Operation    {       public override double getResult()        {            double result = 0;            result = NumberA - NumberB;            return result;        }    }    /// <summary>    /// 乘法类    /// </summary>    class OperationMul : Operation    {        public override double getResult()        {            double result = 0;            result = NumberA * NumberB;            return result;        }    }    /// <summary>    /// 除法类    /// </summary>    class OperationDiv : Operation    {        public override double getResult()        {            double result = 0;            if (NumberB==0)                throw new Exception("除数不能为0。");            result = NumberA / NumberB;            return result;        }    }    /// <summary>    /// 平方类    /// </summary>    class OperationSqr : Operation    {        public override double getResult()        {            double result = 0;            result = NumberB * NumberB;            return result;        }    }    /// <summary>    /// 平方根类    /// </summary>    class OperationSqrt : Operation    {        public override double getResult()        {            double result = 0;            if (NumberB < 0)                throw new Exception("负数不能开平方根。");            result = Math.Sqrt(NumberB);            return result;        }    }    /// <summary>    /// 相反数类    /// </summary>    class OperationReverse : Operation    {        public override double getResult()        {            double result = 0;            result = -NumberB;            return result;        }    }    /// <summary>    /// 运算类工厂    /// </summary>    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;                    }                case "sqr":                    {                        oper = new OperationSqr();                        break;                    }                case "sqrt":                    {                        oper = new OperationSqrt();                        break;                    }                case "+/-":                    {                        oper = new OperationReverse();                        break;                    }            }            return oper;        }    }}

工厂方法模式：和工厂方法不同的地方是加入了“开放-封闭原则”（软件实体类、模块或者函数等等，应该可以扩展，但是不可以修改）规则，将简单工厂的内部判断逻辑移动到了客户端代码来进行，在扩展新功能的时候，简单工厂模式要修改工厂类，工厂方法模式是修改客户端。

计算器实现代码：

using System;using System.Collections.Generic;using System.Text;namespace 工厂方法_计算器{    /// <summary>    /// 运算类    /// </summary>    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; }        }        /// <summary>        /// 得到运算结果        /// </summary>        /// <returns></returns>        public virtual double GetResult()        {            double result = 0;            return result;        }    }    /// <summary>    /// 加法类    /// </summary>    class OperationAdd : Operation    {        public override double GetResult()        {            double result = 0;            result = NumberA + NumberB;            return result;        }    }    /// <summary>    /// 减法类    /// </summary>    class OperationSub : Operation    {        public override double GetResult()        {            double result = 0;            result = NumberA - NumberB;            return result;        }    }    /// <summary>    /// 乘法类    /// </summary>    class OperationMul : Operation    {        public override double GetResult()        {            double result = 0;            result = NumberA * NumberB;            return result;        }    }    /// <summary>    /// 除法类    /// </summary>    class OperationDiv : Operation    {        public override double GetResult()        {            double result = 0;            if (NumberB == 0)                throw new Exception("除数不能为0。");            result = NumberA / NumberB;            return result;        }    }    /// <summary>    /// 工厂方法    /// </summary>    interface IFactory    {        Operation CreateOperation();    }    /// <summary>    /// 专门负责生产“+”的工厂    /// </summary>    class AddFactory : IFactory    {        public Operation CreateOperation()        {            return new OperationAdd();        }    }    /// <summary>    /// 专门负责生产“-”的工厂    /// </summary>    class SubFactory : IFactory    {        public Operation CreateOperation()        {            return new OperationSub();        }    }    /// <summary>    /// 专门负责生产“*”的工厂    /// </summary>    class MulFactory : IFactory    {        public Operation CreateOperation()        {            return new OperationMul();        }    }    /// <summary>    /// 专门负责生产“/”的工厂    /// </summary>    class DivFactory : IFactory    {        public Operation CreateOperation()        {            return new OperationDiv();        }    } }

参考资料：程杰《大话设计模式》

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