設計模式-簡單工廠模式-有解無憂

構造出一個工廠類，需要使用型別的物件，就回傳什么型別的物件
以簡單計算器為例
定義運算類，這是個父類，也是抽象類，這個類定義了一個抽象方法

 1 abstract class Operation{
 2         public abstract double GetResult();
 3         private double _num1;
 4         private double _num2;
 5         public double Num1{
 6             get { return _num1; }
 7             set { _num1 = value; }
 8         }
 9         public double Num2{
10             get { return _num2; }
11             set { _num2 = value; }
12         }
13         public Operation(double num1, double num2){
14             this.Num1 = num1;
15             this.Num2 = num2;
16         }
17     }

定義四個子類分別繼承這個父類

 1 class OperationForMul : Operation{
 2         public OperationForMul(double num1, double num2) : base(num1, num2) { }
 3         public override double GetResult(){
 4             return this.Num1 * this.Num2;
 5         }
 6     }
 7 
 8 class OperationForSub : Operation{
 9         public OperationForSub(double num1, double num2) : base(num1, num2) { }
10         public override double GetResult(){
11             return this.Num1 - this.Num2;
12         }
13     }
14 
15 class OperationForAdd : Operation{
16         public OperationForAdd(double num1, double num2) : base(num1, num2) { }
17         public override double GetResult(){
18             return this.Num1 + this.Num2;
19         }
20     }
21 
22 class OperationForDiv : Operation{
23         public OperationForDiv(double num1, double num2) : base(num1, num2) { }
24         public override double GetResult(){
25             if (this.Num2 == 0){
26                 return 0;
27             }return this.Num1 / this.Num2;
28         }
29     }

定義一個工廠類

public class OperationFactory{
　　public static Operation ReturnOperationItem(string operation, double num1, double num2){
            Operation operationsForOperation = null;
            switch (operation){
                case "+":
                    operationsForOperation = new OperationForAdd(num1, num2);
                    break;
                case "-":
                    operationsForOperation = new OperationForSub(num1, num2);
                    break;
                case "*":
                    operationsForOperation = new OperationForMul(num1, num2);
                    break;
                case "/":
                    operationsForOperation = new OperationForDiv(num1, num2);
                    break;
            }return operationsForOperation;
        }
}

客戶端實作

class Program{
        static void Main(string[] args){
            //使用簡單工廠模式實作計算器
            Console.WriteLine("輸入第一個參與運算的數字");
            double num1 = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("輸入第二個參與運算的數字");
            double num2 = Convert.ToDouble(Console.ReadLine());
            Console.WriteLine("輸入一個運算子");
            string strOperation = Console.ReadLine();
            Console.WriteLine(OperationFactory.ReturnOperationItem(strOperation,num1,num2).GetResult());
            Console.ReadKey();
        }
    }

上面的例子也可以用委托來實作，定義一個和工廠類中方法一樣的委托，將具體的方法傳進去

轉載請註明出處，本文鏈接：https://www.uj5u.com/net/110567.html

標籤：C#

上一篇：檔案操作及編碼格式

下一篇：C# 陣列