ASP.NET四则运算--工厂模式

这次是在ASP.NET上实现四则运算，之前用策略模式实现了，所以这次想着用工厂模式实现一下。

Calculator.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

/// <summary>
///Calculator 的摘要说明
/// </summary>
public class Calculator
{
    //
    //TODO: 在此处添加构造函数逻辑
    //
    private double a = 0;
    private double b = 0;

    public double A
    {
        get { return a; }
        set { a = value; }
    }
    public double B
    {
        get { return b; }
        set { b = value; }
    }
    public virtual double GetResult()
    {
        double result = 0;
        return result;
    }
    
}

class Add : Calculator
{
    public override double GetResult()
    {
        double result = 0;
        result = A + B;
        return result;
    }
}

class Sub : Calculator
{
    public override double GetResult()
    {
        double result = 0;
        result = A - B;
        return result;
    }
}

class Mul : Calculator
{
    public override double GetResult()
    {
        double result = 0;
        result = A * B;
        return result;
    }
}

class Div : Calculator
{
    public override double GetResult()
    {
        double result = 0;
        if (B == 0)
        throw new Exception("除数不能为0");
        result = A / B;
        return result;
    }
}

public class Factory
{
    public static Calculator Cal(string operate)
    {
        Calculator oper = null;
        switch (operate)
        {
            case "+":
                oper = new Add();
                break;
            case "-":
                oper = new Sub();
                break;
            case "*":
                oper = new Mul();
                break;
            case "/":
                oper = new Div();
                break;
        }
        return oper;
    }
}

index.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class index : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //界面加载
    }
    protected void Cal_Click(object sender, EventArgs e)
    {
        Calculator oper;
        string strOperate = DropDownList1.SelectedItem.ToString();
        oper = Factory.Cal(strOperate);
        oper.A = Convert.ToDouble(TextBox1.Text);
        oper.B = Convert.ToDouble(TextBox2.Text);
        string answer = Convert.ToString(oper.GetResult());

        string result = TextBox1.Text + DropDownList1.SelectedItem.ToString() + TextBox2.Text;//把运算式子存在result里面
        if (TextBox3.Text == answer)                                  //如果输入答案与计算出的answer相等
        {
            Response.Write("<script>alert('回答正确!')</script>");          //弹出回答正确
            ListBox1.Items.Add(result + "=" + TextBox3.Text.Trim() + "√");//并把运算式子存在listbox里
        }

        else                                                          //如果答错
        {
            Response.Write("<script>alert('答题错误!')</script>");           //弹出答题错误
            ListBox1.Items.Add(result + "=" + TextBox3.Text.Trim() + "×");//同样把运算式子放在listbox
        }
        TextBox1.Text = "";//把文本框清空，进行下一次出题
        TextBox2.Text = "";
        TextBox3.Text = "";  
    }
}

运行截图：

工厂方法模式。用的地方不太合适！