言成言成啊 | Kit Chen's Blog

java设计模式

发布于2019-10-17 19:35:11，更新于2020-06-15 11:35:07，标签：java design-model  文章会持续修订，转载请注明来源地址：https://meethigher.top/blog

需求

点披萨，可以点不同种类的披萨

比方说奶酪披萨，希腊披萨等等

然后有披萨的准备过程，烘烤过程，切片过程，打包过程

一、传统模式

  • 传统的方式
  • 优点：比较好理解，简单易操作
  • 缺点：违反了设计模式的ocp原则，即对扩展开放，对修改关闭。
  • 即当我们给类增加新功能的时候，尽量不修改代码，或者尽可能少得修改代码
  • 比如，我要新增加一个pizza种类，需要在OrderPizza里面再加一个elseif，这样并不好

类图：

Pizza.java

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package factory.pizza;

/*
 * 将Pizza做成抽象方法
 */
public abstract class Pizza {
	private String name;

	// 准备原材料，不同的披萨，原材料是不一样的。因此，我们做成抽象方法
	public abstract void prepare();

	public void bake() {
		System.out.println(name + " baking;");
	}

	public void cut() {
		System.out.println(name + " cutting;");
	}

	public void box() {
		System.out.println(name + " boxing;");
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getName() {
		return name;
	}
}

CheesePizza.java

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package factory.pizza;

public class CheesePizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		System.out.println("给制作CheesePizza准备原材料 ");
	}

}

GreekPizza.java

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package factory.pizza;

public class GreekPizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		System.out.println("给制作GreekPizza准备原材料");
	}

}

OrderPizza.java

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package factory.order;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import factory.pizza.CheesePizza;
import factory.pizza.GreekPizza;
import factory.pizza.Pizza;

public class OrderPizza {
	//构造方法、构造器
	//下面是传统方式，注释掉
	public OrderPizza() {
		Pizza pizza=null;
		String orderType;//订购pizza的类型
		do {
			orderType=getType();
			if(orderType.equals("greek")) {
				pizza=new GreekPizza();
				pizza.setName("GreekPizza");
			}else if(orderType.equals("cheese")) {
				pizza=new CheesePizza();
				pizza.setName("CheesePizza");
			}else {
				System.out.println("俺们家不做这个pizza，请去其他商店");
				break;
			}
			//输出pizza，制作过程
			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
		}while(true);
	}
	
	
	//写一个方法,可以动态获取pizza类型
	public String getType() {
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		System.out.println("Please input pizza type:");
		String type;
		try {
			type = input.readLine();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return "";
		}
		return type;
	}
}

PizzaStore.java

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package factory.order;

//相当于一个客户端，发出订购任务
public class PizzaStore {
	public static void main(String[] args) {
		new OrderPizza();
	}
	
}

运行结果

二、简单（静态）工厂模式

  • 简单工厂模式是属于创建型模式，是工厂模式的一种。简单工厂模式是由一个工厂对象决定创建出哪一种产品类的实例。
  • 简单工厂模式是工厂模式家族中最简单实用的模式
  • 简单工厂模式:定义了一个创建对象的类，由这个类来封装实例化对象的行为(代码)

类图

Pizza.java&&GreekPizza.java&&CheesePizza.java

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同传统模式

Chinese.java

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package factory.pizza;

public class ChinesePizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		System.out.println("给制作GreekPizza准备原材料");
	}

}

OrderPizza2.java

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package factory.order;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import factory.pizza.Pizza;

public class OrderPizza2 {

	// 定义一个简单工厂对象
	SimpleFactory simpleFactory;
	Pizza pizza = null;
	
	//构造方法
	public OrderPizza2() {
		String orderType = "";// 用户输入的
		do {
			orderType = getType();
			pizza = SimpleFactory.createPizza(orderType);

			// 输出pizza
			if (pizza != null) {
				pizza.prepare();
				pizza.bake();
				pizza.cut();
				pizza.box();
			}else {
				System.out.println("订购披萨失败");
				break;
			}
		} while (true);
	}
	// 写一个方法,可以动态获取pizza类型
	public String getType() {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("Please input pizza type:");
		String type;
		try {
			type = input.readLine();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return "";
		}
		return type;
	}
}

SimpleFactory.java

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package factory.order;

import factory.pizza.CheesePizza;
import factory.pizza.ChinesePizza;
import factory.pizza.GreekPizza;
import factory.pizza.Pizza;

/*
 * 简单(静态)工厂类
 * 也叫静态工厂模式，需要把方法改成static,这样这个方法就直接可以通过类名调用了
 */
public class SimpleFactory {
	
	//根据orderType返回对应的Pizza对象
	public static Pizza createPizza(String orderType) {
		System.out.println("使用简单工厂模式");
		Pizza pizza=null;
		if(orderType.equals("greek")) {
			pizza=new GreekPizza();
			pizza.setName("GreekPizza");
		}else if(orderType.equals("cheese")) {
			pizza=new CheesePizza();
			pizza.setName("CheesePizza");
		}else if(orderType.equals("chinese")) {
			pizza=new ChinesePizza();
			pizza.setName("ChinesePizza");
		}
		return pizza;
	}
}

PizzaStore.java

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public class PizzaStore {
	public static void main(String[] args) {
//		new OrderPizza();
		//使用简单工厂模式
//		new OrderPizza(new SimpleFactory());
		//使用静态工厂模式，其实也是简单工厂，只不过方法是静态的
		new OrderPizza2();
		System.out.println("退出程序，爱你么么哒❤❤");
	}
	
}

运行结果

新需求

客户在点披萨的时候，可以点不同口味的披萨

比方说：北京的奶酪披萨，伦敦的胡椒披萨

思路1：

使用简单工厂模式，创建不同的简单工厂类，BJPizzaSimpleFactory,LDPizzaSimpleFactory等等

但是考虑到项目的规模，以及软件的可维护性、可扩展性并不是特别好

思路2：

使用工厂方法模式

工厂方法模式——定义一个创建对象的抽象方法，由子类决定要实例化的类。工厂方法模式将对象的实例化推迟到子类。

三、工厂方法模式

类图

Pizza.java

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package factory.factoryMethod.pizzaStore.pizza;

/*
 * 将Pizza做成抽象方法
 */
public abstract class Pizza {
	private String name;

	// 准备原材料，不同的披萨，原材料是不一样的。因此，我们做成抽象方法
	public abstract void prepare();

	public void bake() {
		System.out.println(name + " baking;");
	}

	public void cut() {
		System.out.println(name + " cutting;");
	}

	public void box() {
		System.out.println(name + " boxing;");
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getName() {
		return name;
	}
}

BJCheesePizza.java

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package factory.factoryMethod.pizzaStore.pizza;

public class BJCheesePizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		setName("BJCheesePizza");
		System.out.println("BJCheesePizza准备原材料");
	}

}

BJPepperPizza.java

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package factory.factoryMethod.pizzaStore.pizza;

public class BJPepperPizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		setName("BJPepperPizza");
		System.out.println("BJPepperPizza准备原材料");
	}

}

LDCheesePizza.java

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package factory.factoryMethod.pizzaStore.pizza;

public class LDCheesePizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		setName("LDCheesePizza");
		System.out.println("LDCheesePizza准备原材料");
	}

}

LDPepperPizza.java

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package factory.factoryMethod.pizzaStore.pizza;

public class LDPepperPizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		setName("LDPepperPizza");
		System.out.println("LDPepperPizza准备原材料");
	}

}

OrderPizza.java

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package factory.factoryMethod.pizzaStore.order;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import factory.factoryMethod.pizzaStore.pizza.Pizza;

public abstract class OrderPizza {
	// 定义一个抽象方法，createPizza，让各个工厂子类，自己实现
	abstract Pizza createPizza(String orderType);

	// 构造方法
	public OrderPizza() {
		Pizza pizza = null;
		String orderType = null;
		do {
			orderType = getType();
			pizza = createPizza(orderType);//抽象方法由工厂子类完成
			if(pizza==null)
				break;
			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
			System.out.println("披萨已送到你家！！");
			System.out.println();
		} while (true);
	}

	// 从键盘输入中获取披萨类型
	public String getType() {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		String orderType;
		System.out.println("Please input pizza's type:");
		try {
			orderType = input.readLine();
		} catch (IOException e) {
			e.printStackTrace();
			return "";
		}
		return orderType;

	}
}

BJOrderPizza.java

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package factory.factoryMethod.pizzaStore.order;

import factory.factoryMethod.pizzaStore.pizza.BJCheesePizza;
import factory.factoryMethod.pizzaStore.pizza.BJPepperPizza;
import factory.factoryMethod.pizzaStore.pizza.Pizza;

public class BJOrderPizza extends OrderPizza {

	@Override
	Pizza createPizza(String orderType) {
		// TODO Auto-generated method stub
		Pizza pizza=null;
		if(orderType.equals("cheese")) {
			pizza=new BJCheesePizza();
		}else if(orderType.equals("pepper")) {
			pizza=new BJPepperPizza();
		}
		return pizza;
	}

}

LDOrderPizza.java

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package factory.factoryMethod.pizzaStore.order;

import factory.factoryMethod.pizzaStore.pizza.LDCheesePizza;
import factory.factoryMethod.pizzaStore.pizza.LDPepperPizza;
import factory.factoryMethod.pizzaStore.pizza.Pizza;

public class LDOrderPizza extends OrderPizza {

	@Override
	Pizza createPizza(String orderType) {
		// TODO Auto-generated method stub
		Pizza pizza=null;
		if(orderType.equals("cheese")) {
			pizza=new LDCheesePizza();
		}else if(orderType.equals("pepper")) {
			pizza=new LDPepperPizza();
		}
		return pizza;
	}

}

运行结果

四、抽象工厂模式

基本介绍

  • 抽象工厂模式：定义了一个interface用于创建相关或有依赖关系的对象簇，而无需指明具体的类
  • 抽象工厂模式可以将简单工厂模式和工厂方法模式进行整合
  • 从设计层面看，抽象工厂模式就是对简单工厂模式的改进（或者称为进一步的抽象)
  • 将工厂抽象成两层，AbsFactory(抽象工厂)和具体实现的工厂子类。程序员可以根据创建对象类型使用对应的工厂子类。这样将单个的简单工厂类变成了工厂簇，更有利于代码的维护和扩展。

类图

Pizza.java、BJCheesePizza.java、BJPepperPizza.java、LDCheesePizza.java、LDPepperPizza.java

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同工厂方法模式

AbsFactory.java

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package factory.abstractFactory.pizzaStore.order;

import factory.abstractFactory.pizzaStore.pizza.Pizza;

//抽象工厂模式的抽象层
public interface AbsFactory {
	//让下面的子类具体实现
	public Pizza createPizza(String orderType);
}

BJFactory.java

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package factory.abstractFactory.pizzaStore.order;

import factory.abstractFactory.pizzaStore.pizza.BJCheesePizza;
import factory.abstractFactory.pizzaStore.pizza.BJPepperPizza;
import factory.abstractFactory.pizzaStore.pizza.Pizza;

//这是一个工厂子类
public class BJFactory implements AbsFactory {

	@Override
	public Pizza createPizza(String orderType) {
		// TODO Auto-generated method stub
		Pizza pizza=null;
		if(orderType.equals("cheese")) {
			pizza=new BJCheesePizza();
		}else if(orderType.equals("pepper")) {
			pizza=new BJPepperPizza();
		}
		return pizza;
	}

}

LDFactory.java

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package factory.abstractFactory.pizzaStore.order;

import factory.abstractFactory.pizzaStore.pizza.LDCheesePizza;
import factory.abstractFactory.pizzaStore.pizza.LDPepperPizza;
import factory.abstractFactory.pizzaStore.pizza.Pizza;

public class LDFactory implements AbsFactory {

	@Override
	public Pizza createPizza(String orderType) {
		// TODO Auto-generated method stub
		Pizza pizza=null;
		if(orderType.equals("cheese")) {
			pizza=new LDCheesePizza();
		}else if(orderType.equals("pepper")) {
			pizza=new LDPepperPizza();
		}
		return pizza;
	}

}

OrderPizza.java

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package factory.abstractFactory.pizzaStore.order;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import factory.abstractFactory.pizzaStore.pizza.Pizza;

public class OrderPizza {
	AbsFactory absFactory;


	//absFactory可以是北京的，也可以是伦敦的
	public void setAbsFactory(AbsFactory absFactory) {
		Pizza pizza=null;
		String orderType;
		this.absFactory=absFactory;
		do {
			orderType=getType();
			pizza=absFactory.createPizza(orderType);
			if(pizza==null) {
				System.out.println("俺家不做这个披萨哦，请去别家吧❤❤");
				break;
			}
			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
			System.out.println("您订购的Pizza已经在路上了哟❤❤");
			System.out.println();
		}while(true);
	}
	public String getType() {
		String orderType;
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		System.out.println("Please input pizza's type: pepper or cheese");
		try {
			orderType=input.readLine();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			orderType="";
		}
		return orderType;
	}
}

PizzaStore.java

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package factory.abstractFactory.pizzaStore.order;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class PizzaStore {
	public static void main(String[] args) {
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("Please input pizza's location:Beijing or London");
		String loc;
		try {
			loc = input.readLine();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			loc="";
		}
		if(loc.equals("Beijing")) {
			new OrderPizza().setAbsFactory(new BJFactory());
		}else if(loc.equals("London")) {
			new OrderPizza().setAbsFactory(new LDFactory());
		}
		System.out.println("欢迎下次使用，爱你么么哒❤❤");
	}
}

运行结果

发布：2019-10-17 19:35:11
修改：2020-06-15 11:35:07
链接：https://meethigher.top/blog/2019/java-design-model/
标签：java design-model 
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