JAVA设计模式学习笔记-工厂模式

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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

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