工厂方法模式

工厂方法模式：定义一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化延迟到其子类。

（简单理解就是比简单工厂模式多了一个抽象工厂，还有各种实例工厂）解决了简单工厂模式违背了开放-封闭原则的缺点

简单工厂模式在上一篇文章：http://www.cnblogs.com/maggiejyt/p/7561152.html

UML图

 

例子：用工厂模式去实现Ball，比较简单工厂模式

UML图

IFactory：工厂接口

package com.maggie.FactoryMethod;

public interface IFactory {
    public abstract Ball createBall();
}

FootFactory 足球工厂

package com.maggie.FactoryMethod;

public class FootFactory implements IFactory {

    @Override
    public Ball createBall() {
        // TODO Auto-generated method stub
        return new FootBall("white+black");
    }

}

BasketFactory 篮球工厂

package com.maggie.FactoryMethod;

public class BasketFactory implements IFactory {

    @Override
    public Ball createBall() {
        // TODO Auto-generated method stub
        return new BasketBall("oranger");
    }

}

Ball 产品的抽象类（或接口）

package com.maggie.FactoryMethod;

public abstract class Ball {
    private String color;

    public Ball(String color) {
        super();
        this.color = color;
    }

    public Ball() {
        super();
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }
    
    public abstract void play();
    
}

BasketBall 篮球

package com.maggie.FactoryMethod;

public class BasketBall extends Ball {
    @Override
    public void play() {
        String player = "the ball's color is "+this.getColor()+",I am BasketBall";
        System.out.println(player);
    }

    public BasketBall() {
        super();
        // TODO Auto-generated constructor stub
    }

    public BasketBall(String color) {
        super(color);
        // TODO Auto-generated constructor stub
    }



}

FootBall 足球

package com.maggie.FactoryMethod;

public class FootBall extends Ball {


    @Override
    public void play() {
        String player = "the ball's color is "+this.getColor()+",I am FootBall";
        System.out.println(player);
    }

    public FootBall() {
        super();
        // TODO Auto-generated constructor stub
    }

    public FootBall(String color) {
        super(color);
        // TODO Auto-generated constructor stub
    }

    
}

客户端的调用

package com.maggie.FactoryMethod;

public class Client {

    public static void main(String[] args) {
        IFactory iFactory = null;
        
        iFactory = new FootFactory();
        Ball footBall = iFactory.createBall();
        footBall.play();
        
        iFactory = new BasketFactory();
        Ball basketBall = iFactory.createBall();
        basketBall.play();
    }

}

 

输出

the ball's color is white+black,I am FootBall
the ball's color is oranger,I am BasketBall

工厂方法模式跟简单工厂模式的比较：

简单工厂模式把所以品种的产品都在同一个工厂类中生产，则工厂类需要涉及到很多逻辑关系，一旦产品的种类增加，则这个逻辑也就要改变，就要去改变工厂类里面的代码，这样就违背了开放-封闭原则，而工厂模式用一个接口把工厂提取出来每种产品都有自己的工厂类，则增加一种产品就只需增加一个产品的工厂类，就不需要去改变任何类里面的代码，这样就可解决了简单工厂模式违背了开放-封闭原则的缺点。