设计模式 - 出厂模式(factory pattern) 详细说明

出厂模式(factory pattern) 详细说明

本文地址: http://blog.csdn.net/caroline_wendy/article/details/27081511

工厂方法模式: 定义了一个创建对象的接口, 但由子类决定要实例化的类是哪一个. 工厂方法让类把实例化推迟到子类.

包括:

创建者父类(creator), 包括创建对象的方法(取代new详细的对象, 通过參数创建不同的对象), 和一些主要的方法;

详细创建者(concrete creator), 继承创建者父类, 实现创建对象的方法, 不同參数能够创建不同的对象;

产品类父类(product), 包括产品的基本用法, 被创建者父类(creator)的基本方法使用;

详细产品(concrete creator), 继承产品类父类, 对特定的产品进行定制, 供详细创建者(concrete creator)选择创建;

详细方法:

1. 产品类父类(product), 包括产品的一些基本方法.

代码:

/**
 * @time 2014年5月26日
 */
package factory;

import java.util.ArrayList;

/**
 * @author C.L.Wang
 *
 */
public abstract class Pizza {
	String name;
	String dough; //生面团
	String sauce; //调味汁
	
	ArrayList<String> toppings = new ArrayList<String>(); //装饰
	
	void prepare() {
		System.out.println("Preparing " + name);
		System.out.println("Tossing dough..." + dough);
		System.out.println("Adding sauce..." + sauce);
		System.out.println("Adding toppings: ");
		for (int i=0; i<toppings.size(); ++i) {
			System.out.println(" " + toppings.get(i));
		}
	}
	
	void bake() {
		System.out.println("Bake for 25 minutes at 350");
	}
	
	void cut() {
		System.out.println("Cutting the pizza into diagonal slices");
	}
	
	void box() {
		System.out.println("Place pizza in official PizzaStore box");
	}
	
	public String getName() {
		return name;
	}
}

代码:

/**
 * @time 2014年5月26日
 */
package factory;

/**
 * @author C.L.Wang
 *
 */
public class NYStyleCheesePizza extends Pizza {
	public NYStyleCheesePizza() {
		name = "NY Style Sauce and Cheese Pizza";
		dough = "Thin Crust Dough";
		sauce = "Marinara Sauce";
		
		toppings.add("Grated Reggiano Cheese");
	}
}


/**
 * @time 2014年5月26日
 */
package factory;

/**
 * @author C.L.Wang
 *
 */
public class ChicagoStyleCheesePizza extends Pizza {
	public ChicagoStyleCheesePizza() {
		name = "Chicago Style Deep Dish Cheese Pizza";
		dough = "Extra Thick Crust Dough";
		sauce = "Plum Tomato Sauce";
		
		toppings.add("Shredded Mozzarella Cheese");
	}
	
	void cut() {
		System.out.println("Cutting the pizza into square slices");
	}
}

代码:

/**
 * @time 2014年5月26日
 */
package factory;

/**
 * @author C.L.Wang
 *
 */
public abstract class PizzaStore {
	public Pizza orderPizza(String item) {
		Pizza pizza;
		pizza = createPizza(item);
		
		pizza.prepare();
		pizza.bake();
		pizza.cut();
		pizza.box();
		
		return pizza;
	}
	
	abstract Pizza createPizza(String item);
}

代码:

/**
 * @time 2014年5月26日
 */
package factory;

/**
 * @author C.L.Wang
 *
 */
public class NYPizzaStore extends PizzaStore {

	/* (non-Javadoc)
	 * @see factory.PizzaStore#createPizza(java.lang.String)
	 */
	@Override
	Pizza createPizza(String item) {
		// TODO Auto-generated method stub
		
		if (item.equals("cheese")) {
			return new NYStyleCheesePizza();
		} else return null;
	}

}


/**
 * @time 2014年5月26日
 */
package factory;

/**
 * @author C.L.Wang
 *
 */
public class ChicagoPizzaStore extends PizzaStore {

	/* (non-Javadoc)
	 * @see factory.PizzaStore#createPizza(java.lang.String)
	 */
	@Override
	Pizza createPizza(String item) {
		// TODO Auto-generated method stub
		
		if (item.equals("cheese")) {
			return new ChicagoStyleCheesePizza();
		} else return null;
	}

}

代码:

/**
 * @time 2014年5月26日
 */
package factory;

/**
 * @author C.L.Wang
 *
 */
public class PizzaTestDrive {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		PizzaStore nyStore = new NYPizzaStore();
		PizzaStore chicagoStore = new ChicagoPizzaStore();
		
		Pizza pizza = nyStore.orderPizza("cheese");
		System.out.println("Ethan ordered a " + pizza.getName() + "\n");
		
		pizza = chicagoStore.orderPizza("cheese");
		System.out.println("Joel ordered a " + pizza.getName() + "\n");
	}

}

Preparing NY Style Sauce and Cheese Pizza
Tossing dough...Thin Crust Dough
Adding sauce...Marinara Sauce
Adding toppings: 
 Grated Reggiano Cheese
Bake for 25 minutes at 350
Cutting the pizza into diagonal slices
Place pizza in official PizzaStore box
Ethan ordered a NY Style Sauce and Cheese Pizza

Preparing Chicago Style Deep Dish Cheese Pizza
Tossing dough...Extra Thick Crust Dough
Adding sauce...Plum Tomato Sauce
Adding toppings: 
 Shredded Mozzarella Cheese
Bake for 25 minutes at 350
Cutting the pizza into square slices
Place pizza in official PizzaStore box
Joel ordered a Chicago Style Deep Dish Cheese Pizza

依赖倒置原则: 要依赖抽象, 不要依赖详细类.

指导方针:

1. 变量不能够持有详细类的引用.

2. 不要让类派生自详细类.

3. 不要覆盖基类中已实现的方法.