JAVA设计模式之工厂模式

一、简单工厂模式：比较简单，produceProduct方法最好是静态的。它是根据参数来决定返回哪一种类型的product。

public interface Product
{
    public void getName();
}

public class ProductA implements Product
{
    public void getName() 
    {
        System.out.println("I am A.");
    }
}

public class ProductB implements Product
{
    public void getName() 
    {
        System.out.println("I am B.");
    }
}

public class Factory 
{
    public Product produceProduct(String type)
    {
        if(type.equals("A"))
        {
            return new ProductA();
        }
        else if(type.equals("B"))
        {
            return new ProductB();
        }
        else
        {
            return null;
        }
    }
    
    public static void main(String[] args)
    {
        Factory factory = new Factory();
        Product product = factory.produceProduct("A");
        product.getName();
        product = factory.produceProduct("B");
        product.getName();
    }
}

二、工厂方法模式：不同于简单工厂，它将不同的产品放在实现了工厂接口的不同工厂类中，这样就算其中一个工厂出了问题，其他工厂也还可以正常工作。

public interface Product
{
    public void getName();
}

public class ProductA implements Product
{
    public void getName() 
    {
        System.out.println("I am A.");
    }
}

public class ProductB implements Product
{
    public void getName() 
    {
        System.out.println("I am B.");
    }
}

public interface Produce 
{
    public Product produce();
}

public class FactoryA implements Produce
{
    public Product produce()
    {
        return new ProductA();
    }
}

public class FactoryB implements Produce
{
    public Product produce()
    {
        return new ProductB();
    }
}

public class Test 
{
    public static void main(String[] args)
    {
        FactoryA fa = new FactoryA();
        Product p = fa.produce();
        p.getName();
        FactoryB fb = new FactoryB();
        p =    fb.produce();
        p.getName();
    }
}

三、抽象工厂模式：用于创建一系列产品

public interface Fruit 
{
    public void getFruit();
}

public class FruitA implements Fruit
{
    public void getFruit() 
    {
        System.out.println("FruitA");
    }
}

public class FruitB implements Fruit
{
    public void getFruit() 
    {
        System.out.println("FruitB");
    }
}

public interface Vegetable 
{
    public void getVegetable();
}

public class VegetableA implements Vegetable
{
    public void getVegetable() 
    {
        System.out.println("VegetableA");
    }
}

public class VegetableB implements Vegetable
{
    public void getVegetable() 
    {
        System.out.println("VegetableB");
    }
}

public interface AbstractFactory 
{
    public Fruit produceFruit();
    public Vegetable produceVegetable();
}

public class FactoryA implements AbstractFactory
{
    public Fruit produceFruit() 
    {
        return new FruitA();
    }

    public Vegetable produceVegetable() 
    {
        return new VegetableA();
    }
}

public class FactoryB implements AbstractFactory
{
    public Fruit produceFruit() 
    {
        return new FruitB();
    }

    public Vegetable produceVegetable() 
    {
        return new VegetableB();
    }
}

说明：也可以有FactoryAB是return new FruitA()和return new VegetableB()的，或者是FactoryBA是return new FruitB()和return new VegetableA()的。其目的在于创建一系列产品。