软件设计目标—基于简单工厂模式的计算器程序

我不是女神ヾ 2022-06-15 03:16 130阅读 0赞

interface Operation{
        public int getResult(int numberA, int numberB);
    }

class OperationAdd implements Operation{
    public int getResult(int numberA, int numberB){
              return numberA + numberB;
            }
    }

class OperationSub implements Operation{
    	public int getResult(int numberA, int numberB){
    		return numberA - numberB;
    	}
    }

class OperationMul implements Operation{
    	public int getResult(int numberA, int numberB){
    		return numberA * numberB;
    	}
    }

class OperationDiv implements Operation{
    	public int getResult(int numberA, int numberB){
    		int result = 0;
    		if (numberB!=0) 
    			result = numberA / numberB;
    		else{
    			System.out.println("除数不能为0。");
    			System.exit(0);
    		}
    		return result;
    	}
    }

class OperationFactory{
        public Operation createOperate(char operate){
          Operation oper = null;
          switch (operate){
          case '+':
        	  oper = new OperationAdd();
        	  break;
          case '-':
        	  oper = new OperationSub();
        	  break;
          case '*':
        	  oper = new OperationMul();
        	  break;
          case '/':
        	  oper = new OperationDiv();
        	  break;
          }
          return oper; 
        }
    }

import java.io.*;
    class clientSimpleFactory{
    	public static void main(String[] args){
    		int intNumberA=0, intNumberB=0;
    		try{
    			BufferedReader bufR = new BufferedReader( new InputStreamReader(System.in));
    			System.out.print("请输入数字A：");
    			try{
    				intNumberA = new Integer(bufR.readLine()).intValue();
    			}catch(Exception e){
    				System.out.println(e);
    				System.exit(0);
    			} 
    			System.out.print("请输入数字B：");
    			try{
    				intNumberB = new Integer(bufR.readLine()).intValue();
    			}catch(Exception e){
    				System.out.println(e);
    				System.exit(0);
    			} 
    			Operation oper = new OperationFactory().createOperate('+');
    			int result = oper.getResult(intNumberA, intNumberB);
    			System.out.println("result = "+result);
    		}catch(Exception e){
    			System.out.println(e);
    		}
    	}
    }

运行结果：

![Center][]

分析：

如果更改加法运算只需要修改OperationAdd即可。如果需要增加其他运算，只需增加相应的运算子类。

但还需要修改运算类工厂，在switch中增加分支。

所以，基于简单工厂模式的计算器程序，实现了部分开—闭原则。

[Center]: /images/20220615/10b4a1585bdb44fa982d414773856d06.png