设计模式---简单工厂

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简单工厂模式：就是店---很多糕点，你需要通过工厂来生成。目的是为了减少代码，先写一个父类，然后让子类继承这个父类，然后在写一个工厂类，根据switch来调用不同的子类。

测试的时候，直接调用工厂类即可。

直接上代码：

下面的算法是一个 计算器的实现：

1. using System;
2. using System.Collections.Generic;
3. using System.Linq;
4. using System.Text;
5. ?
6. namespace DesignDemo
7. {
8. ????class Operation2
9. ????{
10. ????????private double _numberA;
11. ????????private double _numberB;
12. ?
13. ????????public double numberA
14. ????????{
15. ????????????get {return _numberA;}
16. ????????????set { _numberA = value; }
17. ????????}
18. ?
19. ????????public double numberB
20. ????????{
21. ????????????get { return _numberB; }
22. ????????????set { _numberB = value; }
23. ????????}
24. ?
25. ????????public virtual double GetResult()
26. ????????{
27. ????????????double result = 0d;
28. ????????????return result;
29. ????????}
30. ????}
31. ?
32. ????class OperationAdd : Operation2
33. ????{
34. ????????public override double GetResult()
35. ????????{
36. ????????????double result = 0;
37. ????????????result = numberA + numberB;
38. ????????????return result;
39. ????????}
40. ????}
41. ?
42. ????class OperationSub : Operation2
43. ????{
44. ????????public override double GetResult()
45. ????????{
46. ????????????double result = 0;
47. ????????????result = numberA - numberB;
48. ????????????return result;
49. ????????}
50. ????}
51. ?
52. ????class OperationMul : Operation2
53. ????{
54. ????????public override double GetResult()
55. ????????{
56. ????????????double result = 0;
57. ????????????result = numberA * numberB;
58. ????????????return result;
59. ????????}
60. ????}
61. ?
62. ????class OperationDiv : Operation2
63. ????{
64. ????????public override double GetResult()
65. ????????{
66. ????????????double result = 0;
67. ????????????if (numberB == 0)
68. ????????????{
69. ????????????????throw new Exception("除数不能为0");
70. ????????????}
71. ????????????result = numberA / numberB;
72. ????????????return result;
73. ????????}
74. ????}
75. ?
76. ?
77. ????/************************************************************************/
78. ????/* 建立简单工厂模式：减少耦合，把变化的东西封装成类 */
79. ????/************************************************************************/
80. ?
81. ????class OperationFactory
82. ????{
83. ????????public static Operation2 createOperate(string operate)
84. ????????{
85. ????????????Operation2 per = null;
86. ????????????switch (operate)
87. ????????????{
88. ????????????????case "+":
89. ????????????????????per = new OperationAdd();
90. ????????????????????break;
91. ????????????????case "-":
92. ????????????????????per = new OperationSub();
93. ????????????????????break;
94. ????????????????case "*":
95. ????????????????????per = new OperationMul();
96. ????????????????????break;
97. ????????????????case "/":
98. ????????????????????per = new OperationDiv();
99. ????????????????????break;
100. ????????????}
101. ????????????return per;
102. ????????}
103. ????}
104. }

设计模式---简单工厂

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原文地址：http://www.cnblogs.com/zhuxuekui/p/4783305.html