大话设计模式之一【简单工厂模式】

这章简单工厂模式主要以一个简单的计算器为例来演示，多的不说直接上代码

 

 

首先是 OperationLibrary 类库 的代码

 

 using System; using System.Collections.Generic; using System.Text; namespace OperationLibrary { /// <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> /// 检查输入字符串是否准确 /// </summary> /// <param name="currentNumber"></param> /// <param name="inputString"></param> /// <returns></returns> public static string checkNumberInput(string currentNumber, string inputString) { string result = ""; if(inputString==".") { if(currentNumber.IndexOf(".")<0) { if (currentNumber.Length == 0) result = "0" + inputString; else result = currentNumber + inputString; } } else if (currentNumber == "") { result = inputString; } else { result = currentNumber + inputString; } 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; } } 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; } case "sqr": { oper = new OperationSqr(); break; } case "sqrt": { oper = new OperationSqrt(); break; } case "+/-": { oper = new OperationReverse(); break; } } return oper; } } }

下面是计算器控制台代码

using System; using System.Collections.Generic; using System.Text; using OperationLibrary; namespace 计算器控制台程序 { class Program { static void Main(string[] args) { try { Console.Write("请输入数字A:"); string strNumberA = Console.ReadLine(); Console.Write("请输入选择的符号(+,-,*,/)"); string strOperate = Console.ReadLine(); Console.Write("请输入数字B:"); string strNumberB = Console.ReadLine(); string strResult = ""; Operation oper; oper = OperationFactory.createOperate(strOperate); oper.NumberA = Convert.ToDouble(strNumberA); oper.NumberB = Convert.ToDouble(strNumberB); strResult = oper.GetResult().ToString(); Console.WriteLine("结果是:"+strResult); Console.ReadLine(); }catch(Exception ex) { Console.WriteLine("您的输入有错:"+ex.Message); } } } }