大话设计模式之一【简单工厂模式】

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;
}
}

}

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);
}
}
}
}