第一章：简单工厂模式

面试题目：

请用C++ 、Java 、C# 或者VB.NET 任意一种面向对象语言实现一个计算器控制台程序，要求输入两个数和运算符号，得到结果。

菜鸟实现方法一：

 1 using System;
 2 
 3 namespace TwoDemo
 4 {
 5     class Program
 6     {
 7         static void Main(string[] args)
 8         {
 9             Console.WriteLine("请输入数字A!");
10             string A = Console.ReadLine();
11             Console.WriteLine("请选择运算符号（+ - * /）!");
12             string B = Console.ReadLine();
13             Console.WriteLine("请输入数字B!");
14             string C = Console.ReadLine();
15             string D = "";
16             if (B =="+")
17             {
18                 D = Convert.ToString( Convert.ToDouble(A) + Convert.ToDouble(C));
19             }
20             if (B == "+")
21             {
22                 D = Convert.ToString(Convert.ToDouble(A) + Convert.ToDouble(C));
23             }
24             if (B == "-")
25             {
26                 D = Convert.ToString(Convert.ToDouble(A) - Convert.ToDouble(C));
27             }
28             if (B == "*")
29             {
30                 D = Convert.ToString(Convert.ToDouble(A) * Convert.ToDouble(C));
31             }
32             if (B == "/")
33             {
34                 D = Convert.ToString(Convert.ToDouble(A) / Convert.ToDouble(C));
35             }
36 
37             Console.WriteLine(D);
38             Console.ReadLine();
39         }
40     }
41 }

仔细观察会发现初学者很多的毛病：

1、变量的命名不规范。

2、上面代码的判断分支写法，意味着每个条件都要做判断，等于计算机做了三次无用功。

3、如果是除法的时候，客户输入了0怎么办，如果输入的是字符而不是数字，该怎么办？

菜鸟实现方法二：代码规范

 1 using System;
 2 
 3 namespace ThreeDemo
 4 {
 5     class Program
 6     {
 7         static void Main(string[] args)
 8         {
 9             try
10             {
11                 Console.WriteLine("请输入数字A!");
12                 string strNumberA = Console.ReadLine();
13                 Console.WriteLine("请选择运算符号（+ - * /）!");
14                 string strOperate = Console.ReadLine();
15                 Console.WriteLine("请输入数字B!");
16                 string strNumberB = Console.ReadLine();
17                 string strResult = "";
18 
19                 switch (strOperate)
20                 {
21                     case"+":
22                         strResult = Convert.ToString(Convert.ToDouble(strNumberA) + Convert.ToDouble(strNumberB));
23                         break;
24                     case "-":
25                         strResult = Convert.ToString(Convert.ToDouble(strNumberA) - Convert.ToDouble(strNumberB));
26                         break;
27                     case "*":
28                         strResult = Convert.ToString(Convert.ToDouble(strNumberA) * Convert.ToDouble(strNumberB));
29                         break;
30                     case "/":
31                         if (strNumberB!="0")
32                         {
33                             strResult = Convert.ToString(Convert.ToDouble(strNumberA) - Convert.ToDouble(strNumberB));
34 
35                         }
36                         else
37                         {
38                             strResult = "除数不能为0";
39                         }
40                         break;
41                     default:
42                         break;
43                 }
44 
45                 Console.WriteLine("结果是："+ strResult);
46                 Console.ReadLine();
47             }
48             catch (Exception ex)
49             {
50                 Console.WriteLine("您的输入有错："+ex.Message);
51             }
52         }
53     }
54 }

菜鸟实现方法三：业务的封装,准确的说就是让业务和界面逻辑分开，让它们之间的耦合度下降，只有分离开，才可以达到容易维护或扩展。

Operation运算类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace FourDemo
 6 {
 7     public class Operation
 8     {
 9         public static string GetResult(string numberA, string numberB, string strOperate)
10         {
11             string strResult = string.Empty;
12             switch (strOperate)
13             {
14                 case "+":
15                     strResult = Convert.ToString(Convert.ToDouble(numberA) + Convert.ToDouble(numberB));
16                     break;
17                 case "-":
18                     strResult = Convert.ToString(Convert.ToDouble(numberA) - Convert.ToDouble(numberB));
19                     break;
20                 case "*":
21                     strResult = Convert.ToString(Convert.ToDouble(numberA) * Convert.ToDouble(numberB));
22                     break;
23                 case "/":
24                     if (numberB != "0")
25                     {
26                         strResult = Convert.ToString(Convert.ToDouble(numberA) - Convert.ToDouble(numberB));
27 
28                     }
29                     else
30                     {
31                         strResult = "除数不能为0";
32                     }
33                     break;
34                 default:
35                     break;
36             }
37             return strResult;
38         }
39     }
40 }

客户端代码

 1 using System;
 2 
 3 namespace FourDemo
 4 {
 5     class Program
 6     {
 7         static void Main(string[] args)
 8         {
 9             Console.WriteLine("请输入数字A!");
10             string strNumberA = Console.ReadLine();
11             Console.WriteLine("请选择运算符号（+ - * /）!");
12             string strOperate = Console.ReadLine();
13             Console.WriteLine("请输入数字B!");
14             string strNumberB = Console.ReadLine();
15             string strResult = "";
16             strResult = Operation.GetResult(strNumberA, strNumberB, strOperate);
17             Console.WriteLine("结果是："+strResult);
18             Console.ReadLine();
19         }
20     }
21 }

老鸟实现方法：紧耦合 VS 松耦合

Operation运算类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace OneDemo
 6 {
 7    public class Operation
 8     {
 9         public double NumberA { get; set; }
10         public double NumberB { get; set; }
11         public virtual double GetResult()
12         {
13             double result = 0;
14             return result;
15         }
16     }
17 }

加法类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace OneDemo
 6 {
 7     public class OperationAdd:Operation
 8     {
 9         public override double GetResult()
10         {
11             double result = 0;
12             result = NumberA + NumberB;
13             return result;
14         }
15     }
16 }

减法类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace OneDemo
 6 {
 7    public class OperationSub:Operation
 8     {
 9         public override double GetResult()
10         {
11             double result = 0;
12             result = NumberA - NumberB;
13             return result;
14         }
15     }
16 }

乘法类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace OneDemo
 6 {
 7     /// <summary>
 8     /// 乘法类,继承运算类
 9     /// </summary>
10     public  class OperationMul:Operation
11     {
12         public override double GetResult()
13         {
14             double result = 0;
15             result = NumberA * NumberB;
16             return result;
17         }
18     }
19 }

除法类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace OneDemo
 6 {
 7     /// <summary>
 8     /// 除法类,继承运算类
 9     /// </summary>
10     public class OperationDiv:Operation
11     {
12         public override double GetResult()
13         {
14             double result = 0;
15             if (NumberB==0)
16             {
17                 throw new Exception("除数不能为0");
18             }
19             result = NumberA / NumberB;
20             return result;
21         }
22     }
23 }

简单工程模式：OperationFactory 类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace OneDemo
 6 {
 7    public  class OperationFactory
 8     {
 9         public static Operation createOperate(string opearte)
10         {
11             Operation oper = null;
12             switch (opearte)
13             {
14                 case "+":
15                     oper = new OperationAdd();
16                     break;
17                 case "-":
18                     oper = new OperationSub();
19                     break;
20                 case "*":
21                     oper = new OperationMul();
22                     break;
23                 case "/":
24                     oper = new OperationMul();
25                     break;
26             }
27             return oper;
28         }
29     }
30 }

客户端调用

 1 using System;
 2 
 3 namespace OneDemo
 4 {
 5     class Program
 6     {
 7         static void Main(string[] args)
 8         {
 9             Operation operation = null;
10             operation = OperationFactory.createOperate("+");
11             operation.NumberA = 12;
12             operation.NumberB = 13;
13             Console.WriteLine(operation.GetResult());
14             Console.ReadLine();
15         }
16     }
17 }

posted @ 2020-05-24 11:17 小白膜拜大佬阅读(144) 评论(0) 收藏举报

刷新页面返回顶部

小白膜拜大佬

第一章：简单工厂模式

公告