设计模式-简单工厂模式

类图：

代码：

 1 public class Operation {
 2 
 3     protected double numberA = 0;
 4     protected double numberB = 0;
 5     
 6     
 7     public double getNumberA() {
 8         return numberA;
 9     }
10     public void setNumberA(double numberA) {
11         this.numberA = numberA;
12     }
13     public double getNumberB() {
14         return numberB;
15     }
16     public void setNumberB(double numberB) {
17         this.numberB = numberB;
18     }
19     
20     protected double getResult()
21     {
22         double result = 0;
23         return result;
24     }
25     
26 
27 }

 1 public class AddOperation extends Operation{
 2 
 3     @Override
 4     public double getResult()
 5     {
 6         return numberA + numberB;
 7         
 8     }
 9     
10 
11 }

 1 public class OperationFactory {
 2 
 3     public static Operation createOperation(String operate)
 4     {
 5         if (operate.equals("+"))
 6         {
 7             return new AddOperation();
 8         }
 9         else if (operate.equals("*"))
10         {
11             return new MutiOperation();
12         }
13         return null;
14     }
15 }

 1 public class Client {
 2 
 3     public static void main(String[] args)
 4     {
 5         Operation add = OperationFactory.createOperation("+");
 6         add.setNumberA(1);
 7         add.setNumberB(2);
 8         System.out.println(add.getResult());
 9     }
10 }