设计模式学习笔记（30）——策略模式实现

于 2020-06-13 23:08:41 发布
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CC 4.0 BY-SA版权
分类专栏： 设计模式
版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。
本文链接：https://blog.youkuaiyun.com/Aurora__213/article/details/106739152

一、商场收银软件
商场收银软件，营业员根据顾客所购买的商品的单价和数量，向客户收费。

package operation;

import java.util.Scanner;

class Cash{
	public String list="";
	public Double totalPrice=0.0d;
	public void buttonOK() {
		Scanner sc=new Scanner(System.in);
		System.out.println("输入单价：");
		String price=sc.nextLine();
		System.out.println("输入数量");
		String num=sc.nextLine();
		Double xiaoji=Double.parseDouble(price)*Integer.parseInt(num);
		list+="单价："+price+",数量："+num+",小计："+xiaoji+"\n";
		totalPrice+=xiaoji;
	}
}
public  class Main{
	public static void main(String[] args){
	Cash cash=new Cash();
	boolean flag=true;
	while(flag) {
		cash.buttonOK();
		if(cash.totalPrice>10) {
			flag=false;
		}
	}
	System.out.println("========================"
			);
	System.out.println("清单:\n"+cash.list);
	System.out.println("总价："+cash.totalPrice);
	}
}

二、增加打折

package operation;

import java.util.Scanner;

class Cash{
	public String list="";
	public Double totalPrice=0.00;
	public void buttonOK() {
		Scanner sc=new Scanner(System.in);
		System.out.println("输入单价：");
		String price=sc.nextLine();
		System.out.println("输入数量");
		String num=sc.nextLine();
		System.out.println("输入折扣：(0.)");
		String zhekou=sc.nextLine();
		Double xiaoji=Double.parseDouble(price)*Integer.parseInt(num)*Double.parseDouble(zhekou);
		list+="单价："+price+",数量："+num+",小计："+xiaoji+"\n";
		totalPrice+=xiaoji;
	}
}
public  class Main{
	public static void main(String[] args){
	Cash cash=new Cash();
	boolean flag=true;
	while(flag) {
		cash.buttonOK();
		if(cash.totalPrice>10) {
			flag=false;
		}
	}
	System.out.println("========================");
	System.out.println("清单:\n"+cash.list);
	System.out.println("总价："+cash.totalPrice);
	}
}

三、简单工厂实现
在这里插入图片描述

package operation;

import java.util.Scanner;
abstract class CashSuper{
	public abstract double acceptCash(double money);
}
class CashNormal extends CashSuper{

	public double acceptCash(double money) {
		
		return money;
	}
	
}

class CashRebate extends CashSuper{
	private double discount=0.0d;
	public CashRebate(double discount) {
		this.discount=discount;
	}
	
	public double acceptCash(double money) {
		
		return this.discount *money;
	}
	public double getDiscount() {
		return discount;
	}
	public void setDiscount(double discount) {
		this.discount=discount;
	}
	
}

class CashReturn extends CashSuper{
	private double baseCash;
	private double returnCash;
	public CashReturn(double baseCash,double returnCash) {
		this.baseCash=baseCash;
		this.returnCash=returnCash;
	}
	
	public double acceptCash(double money) {
	
		double result=money;
		if(money>=baseCash) {
			result=money-Math.floor(money/baseCash)*returnCash;
		}
		return result;
	}
	public double getBaseCash() {
		return baseCash;
	}
	public void setBaseCash(double baseCash) {
		this.baseCash=baseCash;
	}
	public double getReturnCash() {
		return returnCash;
	}
	public void setReturnCash(double returnCash) {
		this.returnCash=returnCash;
	}
}

class CashAcceptFactory{
	public static CashSuper createCashAccept(String type,double discount,double basePrice,double returnPrice) {
		CashSuper cs=null;
		if("1".equals(type)) cs=new CashNormal();
		else if("2".equals(type)) cs=new CashRebate(discount);
		else if("3".equals(type)) cs=new CashReturn(basePrice,returnPrice);
		return cs;
		
	}
}
public  class Main{
	public static void main(String[] args){
	boolean flag=true;
	String list="";
	Double totalPrice=0.00;
	while(flag) {
		Scanner sc=new Scanner(System.in);
		System.out.println("输入单价");
		String price=sc.nextLine();
		System.out.println("输入数量");
		String num=sc.nextLine();
		System.out.println("输入折扣类型（1无折扣2打折3满减）：");
		String type=sc.nextLine();
	double discount=0.0d;
	double basePrice=0;
	double returnPrice=0;
	if("2".equals(type)) {
		System.out.println("输入折扣");
		discount=Double.parseDouble(sc.nextLine());
	}
	if("3".equals(type)) {
		System.out.println("返现基础金额");
		basePrice=Double.parseDouble(sc.nextLine());
		System.out.println("返现金额");
		returnPrice=Double.parseDouble(sc.nextLine());
	}
	Double xianjin=Double.parseDouble(price)*Integer.parseInt(num);
	CashSuper cs=CashAcceptFactory.createCashAccept(type, discount, basePrice, returnPrice);
	double xiaoji=cs.acceptCash(xianjin);
	list+="单价："+price+",数量："+num+",折扣："+discount+",返现基础金额"+basePrice+",返现金额"+returnPrice+",小计："+xiaoji+"\n";
	totalPrice+=xiaoji;
	if(totalPrice>10) {
		flag=false;
	}
	}
	System.out.println(list);
	System.out.println("总价："+totalPrice);
	}
}

简单工厂模式虽然也能解决这个问题，但这个模式只是解决对象的创建问题，而由于工厂本身包括了所有的收费方式，商场是可能经常性地更改打折额度和返利额度，每次都要改动这个工厂。面对算法的时常变动，还有更好的方法。
四、策略模式
策略模式：它定义了算法家族，分别封装起来，让它们之间可以相互替换，此模式让算法的变化，不会影响到使用算法的客户。
在这里插入图片描述

package operation;
abstract class Strategy{
	public abstract void AlgorithmInterface();
}
class ConcreteStrategyA extends Strategy{
     public void AlgorithmInterface() {
		System.out.println("算法A实现");
	}
}
class ConcreteStrategyB extends Strategy{

	public void AlgorithmInterface() {
	System.out.println("算法B实现");
	}
	
}
class ConcreteStrategyC extends Strategy{

	public void AlgorithmInterface() {
		System.out.println("算法C实现");
	}
	
}
class Context{
	Strategy strategy;
	public Context(Strategy strategy) {
		this.strategy=strategy;
	}
	public void ContextInterface() {
		strategy.AlgorithmInterface();
	}
}
public  class Main{
	public static void main(String[] args){
		Context context;
		context=new Context(new ConcreteStrategyA());
		context.ContextInterface();
		context=new Context(new ConcreteStrategyB());
		context.ContextInterface();
		context=new Context(new ConcreteStrategyC());
		context.ContextInterface();
	}
}

五、策略模式实现
在这里插入图片描述

package operation;
import java.util.Scanner;
abstract class CashSuper{
	public abstract double AcceptCash(double money);
}

class CashNormal extends CashSuper{
    public double AcceptCash(double money) {
      return money;
	}
	
}

class CashRebate extends CashSuper{
	private double discount=0.0d;
	public CashRebate(double discount) {
		this.discount=discount;
	}

	public double AcceptCash(double money) {
		return this.discount *money;
	}
	public double GetDiscount() {
		return discount;
	}
	public void SetDiscount(double discount) {
		this.discount=discount;
	}
	
}
class CashReturn extends CashSuper{
	private double baseCash;
	private double returnCash;
	public CashReturn(double baseCash,double returnCash) {
		this.baseCash=baseCash;
		this.returnCash=returnCash;
	}
	
	public double AcceptCash(double money) {
		double result=money;
		if(money>=baseCash) {
			result=money-Math.floor(money/baseCash)*returnCash;
		}
		return result;
	}
	public double GetBaseCash() {
		return baseCash;
	}
	public void SetBaseCash(double baseCash) {
		this.baseCash=baseCash;
	}
	public double GetReturnCash() {
		return returnCash;
	}
	public void SetReturnCash(double returnCash) {
		this.returnCash=returnCash;
	}
}

class CashAcceptFactory{
	public static CashSuper CreateCashAccept(String type,double discount,double basePrice,double returnPrice) {
		CashSuper cs=null;
		if("1".equals(type)) cs=new CashNormal();
		else if("2".equals(type)) cs=new CashRebate(discount);
		else if("3".equals(type)) cs=new CashReturn(basePrice,returnPrice);
		return cs;
		
	}
}

class CashContext{
	private CashSuper cs;
	public CashContext(CashSuper csuper) {
		this.cs=csuper;
	}
	public double GetResult(double money) {
		return cs.AcceptCash(money);
	}
}
public  class Main{
	public static void main(String[] args){
	boolean flag=true;
	String list="";
	Double totalPrice=0.00;
	while(flag) {
		Scanner sc=new Scanner(System.in);
		System.out.println("输入单价");
		String price=sc.nextLine();
		System.out.println("输入数量");
		String num=sc.nextLine();
		System.out.println("输入折扣类型（1无折扣2打折3满减）：");
		String type=sc.nextLine();
	double discount=0.0d;
	double basePrice=0;
	double returnPrice=0;
	CashSuper cs=null;
	if("1".equals(type)) cs=new CashNormal();
	else if("2".equals(type)) {
		System.out.println("输入折扣");
		discount=Double.parseDouble(sc.nextLine());
		cs=new CashRebate(discount);
	}
	else if("3".equals(type)) {
		System.out.println("返现基础金额");
		basePrice=Double.parseDouble(sc.nextLine());
		System.out.println("返现金额");
		returnPrice=Double.parseDouble(sc.nextLine());
		cs=new CashReturn(basePrice,returnPrice);
	}
	Double xianjin=Double.parseDouble(price)*Integer.parseInt(num);
	CashContext cc=new CashContext(cs);
	double xiaoji=cc.GetResult(xianjin);
	list+="单价："+price+",数量："+num+",折扣："+discount+",返现基础金额"+basePrice+",返现金额"+returnPrice+",小计："+xiaoji+"\n";
	totalPrice+=xiaoji;
	if(totalPrice>10) {
		flag=false;
	}
	}
	System.out.println(list);
	System.out.println("总价："+totalPrice);
	}
}

六、策略模式与简单工厂结合

package operation;
import java.util.Scanner;
abstract class CashSuper{
 public abstract double AcceptCash(double money);
}

class CashNormal extends CashSuper{
public double AcceptCash(double money) {
		return money;
	}
	
}
class CashRebate extends CashSuper{
	private double discount=0.0d;
	public CashRebate(double discount) {
		this.discount=discount;
	}
	public double AcceptCash(double money) {
		
		return this.discount *money;
	}
	public double GetDiscount() {
		return discount;
	}
	public void SetDiscount(double discount) {
		this.discount=discount;
	}
	
}

class CashReturn extends CashSuper{
	private double baseCash;
	private double returnCash;
	public CashReturn(double baseCash,double returnCash) {
		this.baseCash=baseCash;
		this.returnCash=returnCash;
	}

	public double AcceptCash(double money) {
	
		double result=money;
		if(money>=baseCash) {
			result=money-Math.floor(money/baseCash)*returnCash;
		}
		return result;
	}
	public double GetBaseCash() {
		return baseCash;
	}
	public void SetBaseCash(double baseCash) {
		this.baseCash=baseCash;
	}
	public double GetReturnCash() {
		return returnCash;
	}
	public void SetReturnCash(double returnCash) {
		this.returnCash=returnCash;
	}
}

class CashAcceptFactory{
	public static CashSuper createCashAccept(String type,double discount,double basePrice,double returnPrice) {
		CashSuper cs=null;
		if("1".equals(type)) cs=new CashNormal();
		else if("2".equals(type)) cs=new CashRebate(discount);
		else if("3".equals(type)) cs=new CashReturn(basePrice,returnPrice);
		return cs;
		
	}
}

class CashContext{
	private CashSuper cs=null;
	public CashContext() {
				Scanner sc=new Scanner(System.in);
				System.out.println("输入折扣类型（1无折扣2打折3满减）：");
				String type=sc.nextLine();
			double discount=0.0d;
			double basePrice=0;
			double returnPrice=0;
			if("1".equals(type)) cs=new CashNormal();
			else if("2".equals(type)) {
				System.out.println("输入折扣");
				discount=Double.parseDouble(sc.nextLine());
				cs=new CashRebate(discount);
			}
			else if("3".equals(type)) {
				System.out.println("返现基础金额");
				basePrice=Double.parseDouble(sc.nextLine());
				System.out.println("返现金额");
				returnPrice=Double.parseDouble(sc.nextLine());
				cs=new CashReturn(basePrice,returnPrice);
			}
		}
	public double GetResult(double money) {
		return cs.AcceptCash(money);
	}
}
public  class Main{
	public static void main(String[] args){
	boolean flag=true;
	String list="";
	Double totalPrice=0.00;
	while(flag) {
		Scanner sc=new Scanner(System.in);
		System.out.println("输入单价");
		String price=sc.nextLine();
		System.out.println("输入数量");
		String num=sc.nextLine();
	Double xianjin=Double.parseDouble(price)*Integer.parseInt(num);
	CashContext cc=new CashContext();
	double xiaoji=cc.GetResult(xianjin);
	list+="单价："+price+",数量："+num+",小计："+xiaoji+"\n";
	totalPrice+=xiaoji;
	if(totalPrice>10) {
		flag=false;
	}
	}
	System.out.println(list);
	System.out.println("总价："+totalPrice);
	}
}
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