JAVA设计模式学习笔记-工厂模式

案例1
披萨

不好的设计

所有披萨的父类

package com.java.test.pizzastore.pizza;

public abstract class Pizza {
	protected String name;
	
	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;
	}
}

一种披萨

package com.java.test.pizzastore.pizza;

public class PepperPizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		super.setname("PepperPizza");
		
		System.out.println(name+" preparing;");
	}

}

另一种披萨

package com.java.test.pizzastore.pizza;

public class NYPepperPizza extends Pizza {

	@Override
	public void prepare() {
		// TODO Auto-generated method stub
		super.setname("NYPepperPizza");
		
		System.out.println(name+" preparing;");
	}

}

OrderPizza
这里不好的问题在于每加一种新的披萨，这个类里面也要相应的修改

package com.java.test.pizzastore;

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

import com.java.test.pizzastore.pizza.CheesePizza;
import com.java.test.pizzastore.pizza.ChinesePizza;
import com.java.test.pizzastore.pizza.GreekPizza;
import com.java.test.pizzastore.pizza.PepperPizza;
import com.java.test.pizzastore.pizza.Pizza;

public class OrderPizza {

	public OrderPizza() {
		Pizza pizza = null;
		String ordertype;

		do {
			ordertype = gettype();

			if (ordertype.equals("cheese")) {
				pizza = new CheesePizza();
			} else if (ordertype.equals("greek")) {
				pizza = new GreekPizza();
			} else if (ordertype.equals("pepper")) {
				pizza = new PepperPizza();
			} else if (ordertype.equals("chinese")) {
				pizza = new ChinesePizza();
			} else {
				break;
			}
			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
		} while (true);
	}

	private String gettype() {
		try {
			BufferedReader strin = new BufferedReader(new InputStreamReader(
					System.in));
			System.out.println("input pizza type:");
			String str = strin.readLine();

			return str;
		} catch (IOException e) {
			e.printStackTrace();
			return "";
		}
	}

}

简单工厂模式方案

工厂类

package com.java.test.pizzastore.simplefactory;

import com.java.test.pizzastore.pizza.CheesePizza;
import com.java.test.pizzastore.pizza.GreekPizza;
import com.java.test.pizzastore.pizza.PepperPizza;
import com.java.test.pizzastore.pizza.Pizza;

public class SimplePizzaFactory {

	public Pizza CreatePizza(String ordertype) {
		Pizza pizza = null;

		if (ordertype.equals("cheese")) {
			pizza = new CheesePizza();
		} else if (ordertype.equals("greek")) {
			pizza = new GreekPizza();
		} else if (ordertype.equals("pepper")) {
			pizza = new PepperPizza();
		}
		return pizza;

	}

}

新的OrderPizza

package com.java.test.pizzastore.simplefactory;

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

import com.java.test.pizzastore.pizza.CheesePizza;
import com.java.test.pizzastore.pizza.GreekPizza;
import com.java.test.pizzastore.pizza.PepperPizza;
import com.java.test.pizzastore.pizza.Pizza;

public class OrderPizza {
	SimplePizzaFactory mSimplePizzaFactory;

	public OrderPizza(SimplePizzaFactory mSimplePizzaFactory) {

		setFactory(mSimplePizzaFactory);
	}

	public void setFactory(SimplePizzaFactory mSimplePizzaFactory) {
		Pizza pizza = null;
		String ordertype;

		this.mSimplePizzaFactory = mSimplePizzaFactory;

		do {
			ordertype = gettype();
			pizza = mSimplePizzaFactory.CreatePizza(ordertype);
			if (pizza != null) {
				pizza.prepare();
				pizza.bake();
				pizza.cut();
				pizza.box();
			}

		} while (true);

	}

	private String gettype() {
		try {
			BufferedReader strin = new BufferedReader(new InputStreamReader(
					System.in));
			System.out.println("input pizza type:");
			String str = strin.readLine();

			return str;
		} catch (IOException e) {
			e.printStackTrace();
			return "";
		}
	}

}

工厂方法模式
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

披萨加盟店需求
工厂方法模式设计方案：将披萨项目里的披萨对象实例化功能抽象成抽象方法，在
不同加盟店具体实现功能。

新的OrderPizza

package com.java.test.pizzastore.method;

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

import com.java.test.pizzastore.pizza.CheesePizza;
import com.java.test.pizzastore.pizza.ChinesePizza;
import com.java.test.pizzastore.pizza.GreekPizza;
import com.java.test.pizzastore.pizza.PepperPizza;
import com.java.test.pizzastore.pizza.Pizza;
/*变成了抽象类*/
public abstract class OrderPizza {

	public OrderPizza() {
		Pizza pizza = null;
		String ordertype;

		do {
			ordertype = gettype();
			pizza = createPizza(ordertype);

			pizza.prepare();
			pizza.bake();
			pizza.cut();
			pizza.box();
		} while (true);
	}

	abstract Pizza createPizza(String ordertype);

	private String gettype() {
		try {
			BufferedReader strin = new BufferedReader(new InputStreamReader(
					System.in));
			System.out.println("input pizza type:");
			String str = strin.readLine();

			return str;
		} catch (IOException e) {
			e.printStackTrace();
			return "";
		}
	}

}

一家披萨店
LDOrderPizza

package com.java.test.pizzastore.method;

import com.java.test.pizzastore.pizza.CheesePizza;
import com.java.test.pizzastore.pizza.GreekPizza;
import com.java.test.pizzastore.pizza.LDCheesePizza;
import com.java.test.pizzastore.pizza.LDPepperPizza;
import com.java.test.pizzastore.pizza.PepperPizza;
import com.java.test.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;

	}

}

另一家披萨店
NYOrderPizza

package com.java.test.pizzastore.method;

import com.java.test.pizzastore.pizza.CheesePizza;
import com.java.test.pizzastore.pizza.GreekPizza;
import com.java.test.pizzastore.pizza.NYCheesePizza;
import com.java.test.pizzastore.pizza.NYPepperPizza;
import com.java.test.pizzastore.pizza.PepperPizza;
import com.java.test.pizzastore.pizza.Pizza;

public class NYOrderPizza extends OrderPizza {

	@Override
	Pizza createPizza(String ordertype) {
		Pizza pizza = null;

		if (ordertype.equals("cheese")) {
			pizza = new NYCheesePizza();
		} else if (ordertype.equals("pepper")) {
			pizza = new NYPepperPizza();
		}
		return pizza;

	}

}

抽象工厂模式

抽象工厂模式：定义了一个接口用于创建相关或有依赖关系的对象族，而无需明确
指定具体类

就是把工厂给抽象了一层
AbsFactory

package com.java.test.pizzastore.absfactory;

import com.java.test.pizzastore.pizza.Pizza;

public interface AbsFactory {
	public Pizza CreatePizza(String ordertype) ;
}

一家工厂

package com.java.test.pizzastore.absfactory;

import com.java.test.pizzastore.pizza.LDCheesePizza;
import com.java.test.pizzastore.pizza.LDPepperPizza;
import com.java.test.pizzastore.pizza.Pizza;

public class LDFactory implements AbsFactory {

	@Override
	public Pizza CreatePizza(String ordertype) {
		Pizza pizza = null;

		if (ordertype.equals("cheese")) {
			pizza = new LDCheesePizza();
		} else if (ordertype.equals("pepper")) {
			pizza = new LDPepperPizza();
		}
		return pizza;

	}

}

另一家工厂

package com.java.test.pizzastore.absfactory;

import com.java.test.pizzastore.pizza.NYCheesePizza;
import com.java.test.pizzastore.pizza.NYPepperPizza;
import com.java.test.pizzastore.pizza.Pizza;

public class NYFactory implements AbsFactory {

	
	@Override
	public Pizza CreatePizza(String ordertype) {
		Pizza pizza = null;

		if (ordertype.equals("cheese")) {
			pizza = new NYCheesePizza();
		} else if (ordertype.equals("pepper")) {
			pizza = new NYPepperPizza();
		}
		return pizza;

	}

}

依赖抽象原则
变量不要持有具体类的引用
不要让类继承自具体类，要继承自抽象类或接口
不要覆盖基类中已实现的方法