简单工厂模式

最新推荐文章于 2025-05-26 21:02:41 发布

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最新推荐文章于 2025-05-26 21:02:41 发布

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分类专栏：设计模式

本文链接：https://blog.youkuaiyun.com/weixin_38911591/article/details/83582182

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本文详细介绍了一个简单的Java计算器的设计过程，包括基本的加减乘除运算，异常处理，以及通过工厂模式实现的运算符动态创建。文章展示了如何将业务逻辑与界面分离，确保代码的清晰性和可维护性。

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简单计算器

package jisuanqi;

import java.util.Scanner;

public class jisuanqi {
	public static void main (String [] args) {
		Scanner s=new Scanner(System.in);
		int num1=s.nextInt();
		String option=s.next();
		int num2=s.nextInt();
		int result=0;
		if((option).equals("+"))
			result=num1+num2;
		if((option).equals("-"))
			result=num1-num2;
		if((option).equals("*"))
			result=num1*num2;
		if((option).equals("/"))
			result=num1/num2;
		System.out.println("="+result);
			
	}

}

规范的计算器

package jisuanqi;

import java.util.Scanner;

public class jisuanqi {
	public static void main(String[] args) {
		try {
			Scanner s = new Scanner(System.in);
			System.out.println("请输入数字1：");
			int num1 = s.nextInt();
			System.out.println("请输入运算操作（+/-/*//）：");
			String option = s.next();
			System.out.println("请输入数字2：");
			int num2 = s.nextInt();
			int result = 0;
			switch (option) {
			case "+":
				result = num1 + num2;
				break;
			case "-":
				result = num1 - num2;
				break;
			case "*":
				result = num1 * num2;
				break;
			case "/":
				if (num2 == 0)
					System.out.println("被除数不能为零！");
				else
					result = num1 / num2;
				break;
			}
			System.out.println("=" + result);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

业务的封装，业务、界面分离

operation运算类

package jisuanqi;

public class operation {
	public int getresult(int num1,String operate,int num2)  {
		int result=0;
		switch(operate) {
		case "+":result=num1+num2;break;
		case "-":result=num1-num2;break;
		case "*":result=num1*num2;break;
		case "/":result=num1/num2;break;
		}
		return result;
	}

}

客户端

package jisuanqi;

import java.util.Scanner;


public class client {
	public static void main (String [] args) {
		try {
			Scanner s=new Scanner(System.in);
			System.out.println("请输入数字1：");
			int num1=s.nextInt();
			System.out.println("请输入运算操作（+/-/*//）：");
			String operation=s.next();
			System.out.println("请输入数字2：");
			int num2=s.nextInt();
			operation opt=new operation();
			int result=opt.getresult(num1,operation,num2);
			System.out.println("="+result);
		}catch(Exception e) {
			e.printStackTrace();
		}
	}

}

把加减乘除等运算分离，即使增加修改一个运算不会影响其他的几个

（代码分层次，不能暴露给所有人，有危险）

简单工厂模式：

package jisuanqi;

public  class operation {
	int num1;
	int num2;
	String operation;
	public int getnum1() {
		return num1;
	}
	public void setnum1(int num1) {
		this.num1=num1;
	}
	public int getnum2() {
		return num2;
	}
	public void setnum2(int num2) {
		this.num2=num2;
	}
	
	public int getresult() {
		int result=0;
		return result;
	}
}

package jisuanqi;

public class operationfactory {
	public static operation createoperation(String operation) {
		operation oper=null;
		switch(operation) {
		case"+":oper=new add();break;
		case"-":oper=new sub();break;
		case"*":oper=new mul();break;
		case"/":oper=new div();break;
		}
		return oper;
	}
}

package jisuanqi;

public class add extends operation{
	public int getresult() {
		int result=getnum1()+getnum2();
		return result;
	}

}

package jisuanqi;

public class sub extends operation{
	public int getresult() {
		int result=getnum1()-getnum2();
		return result;
	}
}

package jisuanqi;

public class mul extends operation{
	public int getresult() {
		int result=getnum1()*getnum2();
		return result;
	}
}

package jisuanqi;

public class div extends operation {
	public int getresult() {
		if (getnum2() == 0) {
			System.out.println("被除数不能为零！");
			return -1;
		} else {
			int result = getnum1() / getnum2();
			return result;
		}

	}
}

package jisuanqi;

import java.util.Scanner;


public class client {
	public static void main (String [] args) {
		Scanner s=new Scanner(System.in);
		System.out.println("请输入数字1：");
		int num1=s.nextInt();
		System.out.println("请输入运算操作：");
		String operation=s.next();
		System.out.println("请输入数字2：");
		int num2=s.nextInt();
		
		operation oper=operationfactory.createoperation(operation);
		oper.setnum1(num1);
		oper.setnum2(num2);
		int result=oper.getresult();
		System.out.println("="+result);
	}

}