简单工厂模式

看一个具体的需求
看一个披萨的项目 :要便于披萨种类的扩展,要便于维护
1)披萨的种类很多(比如GreekPizz、CheesePizz等)
2)披萨的制作有prepare、bake、cut、box
3)完成披萨店订购功能。
传统的方式 :
在这里插入图片描述

package com.example.demo.simplefactory.pizzastore.pizza;

/**
 * 将Pizza 类做成抽象
 * @author Administrator
 *
 */
public abstract class Pizza {
	/**
	 * 名字
	 */
	protected String name;
	
	/**
	 * 准备原材料,不同的披萨不一样,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;
	}
	
}
package com.example.demo.simplefactory.pizzastore.pizza;

public class GreekPizza extends Pizza{

	@Override
	public void prepare() {
		System.out.println(" 给希腊披萨 准备原材料");
	}

}
package com.example.demo.simplefactory.pizzastore.pizza;

public class CheesePizza extends Pizza{

	@Override
	public void prepare() {
		System.out.println(" 给制作奶酪披萨,准备原材料");
	}

}
package com.example.demo.simplefactory.pizzastore.order;

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

import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;
import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class OrderPizza {
	
	/**
	 * 构造器
	 */
	public OrderPizza() {
		Pizza pizza = null;
		// 订购披萨的类型
		String orderType;
		do {
			orderType = getType();
			if (orderType.equals("greek")) {
				pizza = new GreekPizza();
				pizza.setName(" 希腊披萨 ");
			} else if (orderType.equals("cheese")) {
				pizza = new CheesePizza();
				pizza.setName(" 奶酪披萨 ");
			} else {
				break;
			}
			// 输出pizza 制作过程
			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
		} while (true);
	}
	
	/**
	 * 写一个方法,可以获取客户希望订购的披萨种类
	 * @return
	 */
	private String getType() {
		try {
			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
			System.out.println("input pizza type : ");
			String string = bufferedReader.readLine();
			return string;
		} catch(IOException e) {
			e.printStackTrace();
			return "";
		}
	}
}
package com.example.demo.simplefactory.pizzastore.order;

/**
 * 相当于一个客户端,发出订购
 * @author Administrator
 *
 */
public class PizzaStore {

	public static void main(String[] args) {
		new OrderPizza();
	}

}

传统的方式优缺点 :
1)优点是比较好理解,简单易操作。
2)缺点是违反了设计模式的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,或者尽可能少修改代码。
3)比如我们这时要新增加一个Pizza的种类,我们需要如下修改。
在这里插入图片描述

package com.example.demo.simplefactory.pizzastore.pizza;

public class PepperPizza extends Pizza{

	@Override
	public void prepare() {
		System.out.println(" 给胡椒披萨准备原材料 ");
	}

}
package com.example.demo.simplefactory.pizzastore.order;

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

import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;
import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;
import com.example.demo.simplefactory.pizzastore.pizza.PepperPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class OrderPizza {
	
	/**
	 * 构造器
	 */
	public OrderPizza() {
		Pizza pizza = null;
		// 订购披萨的类型
		String orderType;
		do {
			orderType = getType();
			if (orderType.equals("greek")) {
				pizza = new GreekPizza();
				pizza.setName(" 希腊披萨 ");
			} else if (orderType.equals("cheese")) {
				pizza = new CheesePizza();
				pizza.setName(" 奶酪披萨 ");
			} else if (orderType.equals("pepper")) {
				pizza = new PepperPizza();
				pizza.setName("胡椒披萨");
			} else {
				break;
			}
			// 输出pizza 制作过程
			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
		} while (true);
	}
	
	/**
	 * 写一个方法,可以获取客户希望订购的披萨种类
	 * @return
	 */
	private String getType() {
		try {
			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
			System.out.println("input pizza type : ");
			String string = bufferedReader.readLine();
			return string;
		} catch(IOException e) {
			e.printStackTrace();
			return "";
		}
	}
}

4)改进的思路分析
分析 :修改代码可以接受,但是如果我们在其它的地方也有创建Pizza的代码,就意味着,也需要修改,而创建Pizza的代码,往往有多处。
思路 :把创建Pizza对象封装到一个类中,这样我们有新的Pizza种类时,只需要修改该类即可,其它有创建到Pizza对象的代码就不需要修改了 -》

简单工厂模式

基本介绍
1)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
2)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位(代码)
3)在软件开发中,当我们会用到大量的创建某种、某类或者某批对象时,就会使用到工厂模式。
在这里插入图片描述
在这里插入图片描述

package com.example.demo.simplefactory.pizzastore.order;

import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;
import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;
import com.example.demo.simplefactory.pizzastore.pizza.PepperPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

/**
 * 简单工厂类
 * @author Administrator
 *
 */
public class SimpleFactory {

	public Pizza createPizza(String orderType) {
		Pizza pizza = null;
		System.out.println("使用简单工厂模式");
		if (orderType.equals("greek")) {
			pizza = new GreekPizza();
			pizza.setName(" 希腊披萨 ");
		} else if (orderType.equals("cheese")) {
			pizza = new CheesePizza();
			pizza.setName(" 奶酪披萨 ");
		} else if (orderType.equals("pepper")) {
			pizza = new PepperPizza();
			pizza.setName("胡椒披萨");
		} 
		return pizza;
	}
	
}
package com.example.demo.simplefactory.pizzastore.order;

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

import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;
import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;
import com.example.demo.simplefactory.pizzastore.pizza.PepperPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class OrderPizza {
	
	/**
	 * 构造器
	 */
	/*
	 * public OrderPizza() { Pizza pizza = null; // 订购披萨的类型 String orderType; do {
	 * orderType = getType(); if (orderType.equals("greek")) { pizza = new
	 * GreekPizza(); pizza.setName(" 希腊披萨 "); } else if (orderType.equals("cheese"))
	 * { pizza = new CheesePizza(); pizza.setName(" 奶酪披萨 "); } else if
	 * (orderType.equals("pepper")) { pizza = new PepperPizza();
	 * pizza.setName("胡椒披萨"); } else { break; } // 输出pizza 制作过程 pizza.prepare();
	 * pizza.bake(); pizza.cut(); pizza.box(); } while (true); }
	 */
	
	/**
	 * 构造器
	 * @param simpleFactory
	 */
	public OrderPizza(SimpleFactory simpleFactory) {
		setFactory(simpleFactory);
	}
	
	/**
	 * 定义一个简单工厂对象
	 */
	private SimpleFactory simpleFactory;
	private Pizza pizza = null;
	private void setFactory(SimpleFactory simpleFactory) {
		// 用户输入的
		String orderTypeString = "";
		// 设置简单工厂对象
		this.simpleFactory = simpleFactory;
		do {
			orderTypeString = getType();
			pizza = this.simpleFactory.createPizza(orderTypeString);
			// 输出pizza
			// 订购成功
			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,可以获取客户希望订购的披萨种类
	 * @return
	 */
	private String getType() {
		try {
			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
			System.out.println("input pizza type : ");
			String string = bufferedReader.readLine();
			return string;
		} catch(IOException e) {
			e.printStackTrace();
			return "";
		}
	}
}
package com.example.demo.simplefactory.pizzastore.order;

/**
 * 相当于一个客户端,发出订购
 * @author Administrator
 *
 */
public class PizzaStore {

	public static void main(String[] args) {
		//new OrderPizza();
		
		// 使用简单工厂模式
		new OrderPizza(new SimpleFactory());
		System.out.println("~~退出程序~~");
	}

}

工厂方法模式

看一个新的需求
披萨项目新的需求 : 客户在点披萨时,可以点不同口味的披萨,比如北京的奶酪pizza、北京的胡椒pizza或者是伦敦的奶酪pizza、伦敦的胡椒pizza。
思路1
使用简单工厂模式,创建不同的简单工厂类,比如BJPizzaSimpleFactory、LDPizzaSimpleFactory等等,从当前这个案例来说,也是可以的,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
工厂方法模式介绍
工厂方法模式设计方案 : 将披萨项目的实例化功能抽象成抽象方法,在不同的口味点餐子类中具体实现。
工厂方法模式 : 定义了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
![在这里插入图片描述](https://img-blog.csdnimg.cn/20200303090520160.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_

package com.example.demo.factorymethod.pizzastore.order;

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

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
import com.fasterxml.jackson.databind.deser.ValueInstantiator.Gettable;

public abstract class OrderPizza {
	
	public OrderPizza() {
		Pizza pizza = null;
		// 订购披萨的类型
		String orderType;
		do {
			orderType = getType();
			createPizza(orderType);
			// 输出Pizza 制作过程
			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
		} while (true);
	}
	
	/**
	 * 定义一个抽象方法,createPizza,让各个工厂子类自己实现
	 * @param orderType
	 * @return
	 */
	abstract Pizza createPizza(String orderType);
	
	/**
	 * 写一个方法,可以获取客户希望订购的披萨种类
	 * @return
	 */
	private String getType() {
		try {
			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
			System.out.println("input pizza type : ");
			String string = bufferedReader.readLine();
			return string;
		} catch(IOException e) {
			e.printStackTrace();
			return "";
		}
	}
}
package com.example.demo.factorymethod.pizzastore.order;

import org.apache.tomcat.util.security.Escape;

import com.example.demo.factorymethod.pizzastore.pizza.LDCheesePizza;
import com.example.demo.factorymethod.pizzastore.pizza.LDPepperPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class LDOrderPizza extends OrderPizza{

	@Override
	Pizza createPizza(String orderType) {
		Pizza pizza = null;
		if (orderType.equals("cheese")) {
			pizza = new LDCheesePizza();
		} else if (orderType.equals("pepper")) {
			pizza = new LDPepperPizza();
		}
		return pizza;
	}

}
package com.example.demo.factorymethod.pizzastore.order;

import com.example.demo.factorymethod.pizzastore.pizza.BJCheesPizza;
import com.example.demo.factorymethod.pizzastore.pizza.BJPepperPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class BJOrderPizza extends OrderPizza{

	@Override
	Pizza createPizza(String orderType) {
		Pizza pizza = null;
		if (orderType.equals("cheese")) {
			pizza = new BJCheesPizza();
		} else if (orderType.equals("pepper")) {
			pizza = new BJPepperPizza();
		}
		return pizza;
	}

}
package com.example.demo.factorymethod.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class BJCheesPizza extends Pizza{

	@Override
	public void prepare() {
		setName("北京的奶酪pizza");
		System.out.println(" 北京的奶酪pizza 准备原材料 ");
	}

}
package com.example.demo.factorymethod.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class BJPepperPizza extends Pizza{

	@Override
	public void prepare() {
		setName(" 北京的胡椒pizza ");
		System.out.println(" 北京的胡椒pizza 准备原材料  ");
	}

}
package com.example.demo.factorymethod.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class LDCheesePizza extends Pizza{

	@Override
	public void prepare() {
		setName(" 伦敦的奶酪pizza ");
		System.out.println(" 伦敦的奶酪pizza 准备原材料 ");
	}

}
package com.example.demo.factorymethod.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class LDPepperPizza extends Pizza{

	@Override
	public void prepare() {
		setName(" 伦敦的胡椒pizza ");
		System.out.println(" 伦敦的胡椒pizza 准备原材料 ");
	}

}
package com.example.demo.factorymethod.pizzastore.order;

public class PizzaStore {

	public static void main(String[] args) {
		// 创建北京口味的各种Pizza
		new BJOrderPizza();
	}

}

抽象工厂模式

基本介绍
1)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
2)抽象工厂模式可以将简单工厂模式工厂方法模式进行整合
3)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)。
4)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,更利于代码的维护和扩展。
5)类图
在这里插入图片描述

package com.example.demo.absfactory.pizzastore.order;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

/**
 * 一个抽象工厂模式的抽象层(接口)
 * @author Administrator
 *
 */
public interface AbsFactory {
	
	/**
	 * 让下面的工厂子类来   具体实现
	 * @param orderType
	 * @return
	 */
	Pizza createPizza(String orderType);
}
package com.example.demo.absfactory.pizzastore.order;

import com.example.demo.absfactory.pizzastore.pizza.BJCheesPizza;
import com.example.demo.factorymethod.pizzastore.pizza.BJPepperPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

/**
 * 这是工厂子类
 * @author Administrator
 *
 */
public class BJFactory implements AbsFactory{

	@Override
	public Pizza createPizza(String orderType) {
		System.out.println("~使用的是抽象工厂模式~");
		Pizza pizza = null;
		if (orderType.equals("cheese")) {
			pizza = new BJCheesPizza();
		} else if (orderType.equals("pepper") ) {
			pizza = new BJPepperPizza();
		}
		return pizza;
	}

}
package com.example.demo.absfactory.pizzastore.order;

import com.example.demo.absfactory.pizzastore.pizza.LDCheesePizza;
import com.example.demo.absfactory.pizzastore.pizza.LDPepperPizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class LDFactory implements AbsFactory{

	@Override
	public Pizza createPizza(String orderType) {
		System.out.println("~使用的是抽象工厂模式~");
		Pizza pizza = null;
		if (orderType.equals("cheese")) {
			pizza = new LDCheesePizza();
		} else if (orderType.equals("pepper")) {
			pizza = new LDPepperPizza();
		}
		return pizza;
	}

}
package com.example.demo.absfactory.pizzastore.order;

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

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class OrderPizza {
	
	private AbsFactory factory;
	
	/**
	 * 构造器
	 * @param factory
	 */
	public OrderPizza(AbsFactory factory) {
		setFactory(factory);
	}
	
	private void setFactory(AbsFactory factory) {
		Pizza pizza = null;
		// 用户输入
		String orderTypeString = "";
		this.factory = factory;
		do {
			orderTypeString = getType();
			pizza = factory.createPizza(orderTypeString);
			if (pizza != null) {
				pizza.prepare();
				pizza.bake();
				pizza.cut();
				pizza.box();
			} else {
				System.out.println("~订购失败~");
				break;
			}
		} while (true);
	}

	/**
	 * 写一个方法,可以获取客户希望订购的披萨种类
	 * @return
	 */
	private String getType() {
		try {
			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
			System.out.println("input pizza type : ");
			String string = bufferedReader.readLine();
			return string;
		} catch(IOException e) {
			e.printStackTrace();
			return "";
		}
	}
}
package com.example.demo.absfactory.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class BJCheesPizza extends Pizza{

	@Override
	public void prepare() {
		setName("北京的奶酪pizza");
		System.out.println(" 北京的奶酪pizza 准备原材料 ");
	}

}
package com.example.demo.absfactory.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class BJPepperPizza extends Pizza{

	@Override
	public void prepare() {
		setName(" 北京的胡椒pizza ");
		System.out.println(" 北京的胡椒pizza 准备原材料  ");
	}

}
package com.example.demo.absfactory.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class LDCheesePizza extends Pizza{

	@Override
	public void prepare() {
		setName(" 伦敦的奶酪pizza ");
		System.out.println(" 伦敦的奶酪pizza 准备原材料 ");
	}

}
package com.example.demo.absfactory.pizzastore.pizza;

import com.example.demo.simplefactory.pizzastore.pizza.Pizza;

public class LDPepperPizza extends Pizza{

	@Override
	public void prepare() {
		setName(" 伦敦的胡椒pizza ");
		System.out.println(" 伦敦的胡椒pizza 准备原材料 ");
	}

}
package com.example.demo.absfactory.pizzastore.order;

public class PizzaStore {
	public static void main(String[] args) {
		new OrderPizza(new BJFactory());
	}
}

工厂模式在JDK-Calendar 应用的源码分析
1)JDK中的Calendar类中,使用了简单工厂模式

public static Calendar getInstance()
    {
        return createCalendar(TimeZone.getDefault(), Locale.getDefault(Locale.Category.FORMAT));
    }
private static Calendar createCalendar(TimeZone zone,
                                           Locale aLocale)
    {
        CalendarProvider provider =
            LocaleProviderAdapter.getAdapter(CalendarProvider.class, aLocale)
                                 .getCalendarProvider();
        if (provider != null) {
            try {
                return provider.getInstance(zone, aLocale);
            } catch (IllegalArgumentException iae) {
                // fall back to the default instantiation
            }
        }

        Calendar cal = null;

        if (aLocale.hasExtensions()) {
            String caltype = aLocale.getUnicodeLocaleType("ca");
            if (caltype != null) {
                switch (caltype) {
                case "buddhist":
                cal = new BuddhistCalendar(zone, aLocale);
                    break;
                case "japanese":
                    cal = new JapaneseImperialCalendar(zone, aLocale);
                    break;
                case "gregory":
                    cal = new GregorianCalendar(zone, aLocale);
                    break;
                }
            }
        }
        if (cal == null) {
            // If no known calendar type is explicitly specified,
            // perform the traditional way to create a Calendar:
            // create a BuddhistCalendar for th_TH locale,
            // a JapaneseImperialCalendar for ja_JP_JP locale, or
            // a GregorianCalendar for any other locales.
            // NOTE: The language, country and variant strings are interned.
            if (aLocale.getLanguage() == "th" && aLocale.getCountry() == "TH") {
                cal = new BuddhistCalendar(zone, aLocale);
            } else if (aLocale.getVariant() == "JP" && aLocale.getLanguage() == "ja"
                       && aLocale.getCountry() == "JP") {
                cal = new JapaneseImperialCalendar(zone, aLocale);
            } else {
                cal = new GregorianCalendar(zone, aLocale);
            }
        }
        return cal;
    }

工厂模式小结 :
1)工厂模式的意义
将实例化对象的代码提取出来,放到一个类中统一管理和维护,达到和主项目的依赖关系的解耦。从而提高项目的扩展和维护性。
2)三种工厂模式
3)设计模式的依赖抽象原则
创建对象实例时,不要直接new类,而是把这个new类的动作放在一个工厂的方法中,并返回。有的书上说,变量不要直接持有具体类的引用。
不要让类继承具体类,而是继承抽象类或者是实现interface(接口)
不要覆盖基类中已经实现的方法。

@[TOC](图解Java设计模式之工厂模式)## 简单工厂模式看一个具体的需求看一个披萨的项目 :要便于披萨种类的扩展,要便于维护1)披萨的种类很多(比如GreekPizz、CheesePizz等)2)披萨的制作有prepare、bake、cut、box3)完成披萨店订购功能。传统的方式 :![在这里插入图片描述](https://img-blog.csdnimg.cn/20200302165146817.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_70)```package com.example.demo.simplefactory.pizzastore.pizza;
/** * 将Pizza 类做成抽象 * @author Administrator * */public abstract class Pizza {/** * 名字 */protected String name;/** * 准备原材料,不同的披萨不一样,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;}}package com.example.demo.simplefactory.pizzastore.pizza;
public class GreekPizza extends Pizza{
@Overridepublic void prepare() {System.out.println(" 给希腊披萨 准备原材料");}
}package com.example.demo.simplefactory.pizzastore.pizza;
public class CheesePizza extends Pizza{
@Overridepublic void prepare() {System.out.println(" 给制作奶酪披萨,准备原材料");}
}package com.example.demo.simplefactory.pizzastore.order;
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;
import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class OrderPizza {/** * 构造器 */public OrderPizza() {Pizza pizza = null;// 订购披萨的类型String orderType;do {orderType = getType();if (orderType.equals("greek")) {pizza = new GreekPizza();pizza.setName(" 希腊披萨 ");} else if (orderType.equals("cheese")) {pizza = new CheesePizza();pizza.setName(" 奶酪披萨 ");} else {break;}// 输出pizza 制作过程pizza.prepare();pizza.bake();pizza.cut();pizza.box();} while (true);}/** * 写一个方法,可以获取客户希望订购的披萨种类 * @return */private String getType() {try {BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));System.out.println("input pizza type : ");String string = bufferedReader.readLine();return string;} catch(IOException e) {e.printStackTrace();return "";}}}package com.example.demo.simplefactory.pizzastore.order;
/** * 相当于一个客户端,发出订购 * @author Administrator * */public class PizzaStore {
public static void main(String[] args) {new OrderPizza();}
}```传统的方式优缺点 :1)优点是比较好理解,简单易操作。2)缺点是违反了设计模式的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,或者尽可能少修改代码。3)比如我们这时要新增加一个Pizza的种类,我们需要如下修改。![在这里插入图片描述](https://img-blog.csdnimg.cn/20200302165644275.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_70)
```package com.example.demo.simplefactory.pizzastore.pizza;
public class PepperPizza extends Pizza{
@Overridepublic void prepare() {System.out.println(" 给胡椒披萨准备原材料 ");}
}package com.example.demo.simplefactory.pizzastore.order;
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;
import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;import com.example.demo.simplefactory.pizzastore.pizza.PepperPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class OrderPizza {/** * 构造器 */public OrderPizza() {Pizza pizza = null;// 订购披萨的类型String orderType;do {orderType = getType();if (orderType.equals("greek")) {pizza = new GreekPizza();pizza.setName(" 希腊披萨 ");} else if (orderType.equals("cheese")) {pizza = new CheesePizza();pizza.setName(" 奶酪披萨 ");} else if (orderType.equals("pepper")) {pizza = new PepperPizza();pizza.setName("胡椒披萨");} else {break;}// 输出pizza 制作过程pizza.prepare();pizza.bake();pizza.cut();pizza.box();} while (true);}/** * 写一个方法,可以获取客户希望订购的披萨种类 * @return */private String getType() {try {BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));System.out.println("input pizza type : ");String string = bufferedReader.readLine();return string;} catch(IOException e) {e.printStackTrace();return "";}}}```4)改进的思路分析分析 :修改代码可以接受,但是如果我们在其它的地方也有创建Pizza的代码,就意味着,也需要修改,而创建Pizza的代码,往往有多处。思路 :把创建Pizza对象封装到一个类中,这样我们有新的Pizza种类时,只需要修改该类即可,其它有创建到Pizza对象的代码就不需要修改了 -》## 简单工厂模式**基本介绍**1)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2)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位(代码)3)在软件开发中,当我们会用到大量的创建某种、某类或者某批对象时,就会使用到工厂模式。![在这里插入图片描述](https://img-blog.csdnimg.cn/20200302171554396.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_70)![在这里插入图片描述](https://img-blog.csdnimg.cn/20200302175645117.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_70)```package com.example.demo.simplefactory.pizzastore.order;
import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;import com.example.demo.simplefactory.pizzastore.pizza.PepperPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
/** * 简单工厂类 * @author Administrator * */public class SimpleFactory {
public Pizza createPizza(String orderType) {Pizza pizza = null;System.out.println("使用简单工厂模式");if (orderType.equals("greek")) {pizza = new GreekPizza();pizza.setName(" 希腊披萨 ");} else if (orderType.equals("cheese")) {pizza = new CheesePizza();pizza.setName(" 奶酪披萨 ");} else if (orderType.equals("pepper")) {pizza = new PepperPizza();pizza.setName("胡椒披萨");} return pizza;}}package com.example.demo.simplefactory.pizzastore.order;
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;
import com.example.demo.simplefactory.pizzastore.pizza.CheesePizza;import com.example.demo.simplefactory.pizzastore.pizza.GreekPizza;import com.example.demo.simplefactory.pizzastore.pizza.PepperPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class OrderPizza {/** * 构造器 *//* * public OrderPizza() { Pizza pizza = null; // 订购披萨的类型 String orderType; do { * orderType = getType(); if (orderType.equals("greek")) { pizza = new * GreekPizza(); pizza.setName(" 希腊披萨 "); } else if (orderType.equals("cheese")) * { pizza = new CheesePizza(); pizza.setName(" 奶酪披萨 "); } else if * (orderType.equals("pepper")) { pizza = new PepperPizza(); * pizza.setName("胡椒披萨"); } else { break; } // 输出pizza 制作过程 pizza.prepare(); * pizza.bake(); pizza.cut(); pizza.box(); } while (true); } *//** * 构造器 * @param simpleFactory */public OrderPizza(SimpleFactory simpleFactory) {setFactory(simpleFactory);}/** * 定义一个简单工厂对象 */private SimpleFactory simpleFactory;private Pizza pizza = null;private void setFactory(SimpleFactory simpleFactory) {// 用户输入的String orderTypeString = "";// 设置简单工厂对象this.simpleFactory = simpleFactory;do {orderTypeString = getType();pizza = this.simpleFactory.createPizza(orderTypeString);// 输出pizza// 订购成功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,可以获取客户希望订购的披萨种类 * @return */private String getType() {try {BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));System.out.println("input pizza type : ");String string = bufferedReader.readLine();return string;} catch(IOException e) {e.printStackTrace();return "";}}}package com.example.demo.simplefactory.pizzastore.order;
/** * 相当于一个客户端,发出订购 * @author Administrator * */public class PizzaStore {
public static void main(String[] args) {//new OrderPizza();// 使用简单工厂模式new OrderPizza(new SimpleFactory());System.out.println("~~退出程序~~");}
}```## 工厂方法模式**看一个新的需求**披萨项目新的需求 : 客户在点披萨时,可以点不同口味的披萨,比如北京的奶酪pizza、北京的胡椒pizza或者是伦敦的奶酪pizza、伦敦的胡椒pizza。**思路1**使用简单工厂模式,创建不同的简单工厂类,比如BJPizzaSimpleFactory、LDPizzaSimpleFactory等等,从当前这个案例来说,也是可以的,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**工厂方法模式介绍**工厂方法模式设计方案 : 将披萨项目的实例化功能抽象成抽象方法,在不同的口味点餐子类中具体实现。工厂方法模式 : 定义了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**。![!\[在这里插入图片描述\](https://img-blog.csdnimg.cn/20200303090520160.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_](https://img-blog.csdnimg.cn/20200303092224750.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_70)```package com.example.demo.factorymethod.pizzastore.order;
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;import com.fasterxml.jackson.databind.deser.ValueInstantiator.Gettable;
public abstract class OrderPizza {public OrderPizza() {Pizza pizza = null;// 订购披萨的类型String orderType;do {orderType = getType();createPizza(orderType);// 输出Pizza 制作过程pizza.prepare();pizza.bake();pizza.cut();pizza.box();} while (true);}/** * 定义一个抽象方法,createPizza,让各个工厂子类自己实现 * @param orderType * @return */abstract Pizza createPizza(String orderType);/** * 写一个方法,可以获取客户希望订购的披萨种类 * @return */private String getType() {try {BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));System.out.println("input pizza type : ");String string = bufferedReader.readLine();return string;} catch(IOException e) {e.printStackTrace();return "";}}}package com.example.demo.factorymethod.pizzastore.order;
import org.apache.tomcat.util.security.Escape;
import com.example.demo.factorymethod.pizzastore.pizza.LDCheesePizza;import com.example.demo.factorymethod.pizzastore.pizza.LDPepperPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class LDOrderPizza extends OrderPizza{
@OverridePizza createPizza(String orderType) {Pizza pizza = null;if (orderType.equals("cheese")) {pizza = new LDCheesePizza();} else if (orderType.equals("pepper")) {pizza = new LDPepperPizza();}return pizza;}
}package com.example.demo.factorymethod.pizzastore.order;
import com.example.demo.factorymethod.pizzastore.pizza.BJCheesPizza;import com.example.demo.factorymethod.pizzastore.pizza.BJPepperPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class BJOrderPizza extends OrderPizza{
@OverridePizza createPizza(String orderType) {Pizza pizza = null;if (orderType.equals("cheese")) {pizza = new BJCheesPizza();} else if (orderType.equals("pepper")) {pizza = new BJPepperPizza();}return pizza;}
}package com.example.demo.factorymethod.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class BJCheesPizza extends Pizza{
@Overridepublic void prepare() {setName("北京的奶酪pizza");System.out.println(" 北京的奶酪pizza 准备原材料 ");}
}package com.example.demo.factorymethod.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class BJPepperPizza extends Pizza{
@Overridepublic void prepare() {setName(" 北京的胡椒pizza ");System.out.println(" 北京的胡椒pizza 准备原材料  ");}
}package com.example.demo.factorymethod.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class LDCheesePizza extends Pizza{
@Overridepublic void prepare() {setName(" 伦敦的奶酪pizza ");System.out.println(" 伦敦的奶酪pizza 准备原材料 ");}
}package com.example.demo.factorymethod.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class LDPepperPizza extends Pizza{
@Overridepublic void prepare() {setName(" 伦敦的胡椒pizza ");System.out.println(" 伦敦的胡椒pizza 准备原材料 ");}
}package com.example.demo.factorymethod.pizzastore.order;
public class PizzaStore {
public static void main(String[] args) {// 创建北京口味的各种Pizzanew BJOrderPizza();}
}
```## 抽象工厂模式基本介绍1)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2)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3)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)。4)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,更利于代码的维护和扩展。5)类图![在这里插入图片描述](https://img-blog.csdnimg.cn/20200303092755922.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW8xMjk5MDAyNzg4,size_16,color_FFFFFF,t_70)```package com.example.demo.absfactory.pizzastore.order;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
/** * 一个抽象工厂模式的抽象层(接口) * @author Administrator * */public interface AbsFactory {/** * 让下面的工厂子类来   具体实现 * @param orderType * @return */Pizza createPizza(String orderType);}package com.example.demo.absfactory.pizzastore.order;
import com.example.demo.absfactory.pizzastore.pizza.BJCheesPizza;import com.example.demo.factorymethod.pizzastore.pizza.BJPepperPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
/** * 这是工厂子类 * @author Administrator * */public class BJFactory implements AbsFactory{
@Overridepublic Pizza createPizza(String orderType) {System.out.println("~使用的是抽象工厂模式~");Pizza pizza = null;if (orderType.equals("cheese")) {pizza = new BJCheesPizza();} else if (orderType.equals("pepper") ) {pizza = new BJPepperPizza();}return pizza;}
}package com.example.demo.absfactory.pizzastore.order;
import com.example.demo.absfactory.pizzastore.pizza.LDCheesePizza;import com.example.demo.absfactory.pizzastore.pizza.LDPepperPizza;import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class LDFactory implements AbsFactory{
@Overridepublic Pizza createPizza(String orderType) {System.out.println("~使用的是抽象工厂模式~");Pizza pizza = null;if (orderType.equals("cheese")) {pizza = new LDCheesePizza();} else if (orderType.equals("pepper")) {pizza = new LDPepperPizza();}return pizza;}
}package com.example.demo.absfactory.pizzastore.order;
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class OrderPizza {private AbsFactory factory;/** * 构造器 * @param factory */public OrderPizza(AbsFactory factory) {setFactory(factory);}private void setFactory(AbsFactory factory) {Pizza pizza = null;// 用户输入String orderTypeString = "";this.factory = factory;do {orderTypeString = getType();pizza = factory.createPizza(orderTypeString);if (pizza != null) {pizza.prepare();pizza.bake();pizza.cut();pizza.box();} else {System.out.println("~订购失败~");break;}} while (true);}
/** * 写一个方法,可以获取客户希望订购的披萨种类 * @return */private String getType() {try {BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));System.out.println("input pizza type : ");String string = bufferedReader.readLine();return string;} catch(IOException e) {e.printStackTrace();return "";}}}package com.example.demo.absfactory.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class BJCheesPizza extends Pizza{
@Overridepublic void prepare() {setName("北京的奶酪pizza");System.out.println(" 北京的奶酪pizza 准备原材料 ");}
}package com.example.demo.absfactory.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class BJPepperPizza extends Pizza{
@Overridepublic void prepare() {setName(" 北京的胡椒pizza ");System.out.println(" 北京的胡椒pizza 准备原材料  ");}
}package com.example.demo.absfactory.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class LDCheesePizza extends Pizza{
@Overridepublic void prepare() {setName(" 伦敦的奶酪pizza ");System.out.println(" 伦敦的奶酪pizza 准备原材料 ");}
}package com.example.demo.absfactory.pizzastore.pizza;
import com.example.demo.simplefactory.pizzastore.pizza.Pizza;
public class LDPepperPizza extends Pizza{
@Overridepublic void prepare() {setName(" 伦敦的胡椒pizza ");System.out.println(" 伦敦的胡椒pizza 准备原材料 ");}
}package com.example.demo.absfactory.pizzastore.order;
public class PizzaStore {public static void main(String[] args) {new OrderPizza(new BJFactory());}}```工厂模式在JDK-Calendar 应用的源码分析1)JDK中的Calendar类中,使用了简单工厂模式```public static Calendar getInstance()    {        return createCalendar(TimeZone.getDefault(), Locale.getDefault(Locale.Category.FORMAT));    }private static Calendar createCalendar(TimeZone zone,                                           Locale aLocale)    {        CalendarProvider provider =            LocaleProviderAdapter.getAdapter(CalendarProvider.class, aLocale)                                 .getCalendarProvider();        if (provider != null) {            try {                return provider.getInstance(zone, aLocale);            } catch (IllegalArgumentException iae) {                // fall back to the default instantiation            }        }
        Calendar cal = null;
        if (aLocale.hasExtensions()) {            String caltype = aLocale.getUnicodeLocaleType("ca");            if (caltype != null) {                switch (caltype) {                case "buddhist":                cal = new BuddhistCalendar(zone, aLocale);                    break;                case "japanese":                    cal = new JapaneseImperialCalendar(zone, aLocale);                    break;                case "gregory":                    cal = new GregorianCalendar(zone, aLocale);                    break;                }            }        }        if (cal == null) {            // If no known calendar type is explicitly specified,            // perform the traditional way to create a Calendar:            // create a BuddhistCalendar for th_TH locale,            // a JapaneseImperialCalendar for ja_JP_JP locale, or            // a GregorianCalendar for any other locales.            // NOTE: The language, country and variant strings are interned.            if (aLocale.getLanguage() == "th" && aLocale.getCountry() == "TH") {                cal = new BuddhistCalendar(zone, aLocale);            } else if (aLocale.getVariant() == "JP" && aLocale.getLanguage() == "ja"                       && aLocale.getCountry() == "JP") {                cal = new JapaneseImperialCalendar(zone, aLocale);            } else {                cal = new GregorianCalendar(zone, aLocale);            }        }        return cal;    }```工厂模式小结 : 1)工厂模式的意义将实例化对象的代码提取出来,放到一个类中统一管理和维护,达到和主项目的依赖关系的解耦。从而提高项目的扩展和维护性。2)三种工厂模式3)设计模式的**依赖抽象**原则创建对象实例时,不要直接new类,而是把这个new类的动作放在一个工厂的方法中,并返回。有的书上说,变量不要直接持有具体类的引用。不要让类继承具体类,而是继承抽象类或者是实现interface(接口)不要覆盖基类中已经实现的方法。

posted on 2020-03-03 14:29  小小一  阅读(678)  评论(0编辑  收藏  举报