构造型模式之（Factory Method）工厂方法模式

1.如果你期望推迟确定所需要实例化的类，可使用（Factory Method）工厂方法模式
2.举例

//产品接口
public interface IProduct {
    void one();
    void setFactoryName(String string);
}

//产品A
public class ProductA implements IProduct{

    @Override
    public void one() {
        // TODO Auto-generated method stub
        System.out.println("one productA");
    }

    @Override
    public void setFactoryName(String string) {
        // TODO Auto-generated method stub
        System.out.println(string + "->" + "ProductA");
    }

}

//产品B
public class ProductB implements IProduct{

    @Override
    public void one() {
        // TODO Auto-generated method stub
        System.out.println("one ProductB");
    }

    @Override
    public void setFactoryName(String string) {
        // TODO Auto-generated method stub
        System.out.println(string + "->" + "ProductB");
    }

}

//工厂抽象类
public abstract class Factory {
    abstract <T extends IProduct>T createProduct(T t);
    abstract String getFactoryName();
}

//第一个工厂
public class FirstFactory extends Factory{

    @Override
    <T extends IProduct> T createProduct(T t) {
        // TODO Auto-generated method stub
        T product = null;
        try {
            product = (T)Class.forName(t.getClass().getName()).newInstance();
            ((IProduct)product).setFactoryName(getFactoryName());
        } catch (InstantiationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return puduct;
    }

    @Override
    String getFactoryName() {
        // TODO Auto-generated method stub
        return "FirstFactory";
    }

}

//第二个工厂
public class SecondFactory extends Factory{

    @Override
    <T extends IProduct> T createProduct(T t) {
        // TODO Auto-generated method stub
        T product = null;
        try {
            product = (T)Class.forName(t.getClass().getName()).newInstance();
            ((IProduct)product).setFactoryName(getFactoryName());
        } catch (InstantiationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        };
        return product;
    }

    @Override
    String getFactoryName() {
        // TODO Auto-generated method stub
        return "SecondFactory";
    }

}

//测试类
public class Test {
    public static void main(String[] args){
        Factory ff = new FirstFactory();
        IProduct a1 = ff.createProduct(new ProductA());
        IProduct b1 = ff.createProduct(new ProductB());

        Factory sf = new SecondFactory();
        IProduct a2 = sf.createProduct(new ProductA());

        a1.one();
        b1.one();
        a2.one();
    }
}

//结果
FirstFactory->ProductA
FirstFactory->ProductB
SecondFactory->ProductA
one productA
one ProductB
one productA

3.总结：（Factory Method）工厂方法模式的主要意图是用于创建对象的接口，同时控制对哪个类进行实例化。通过该模式我们可以根据一个类层次结构中的子类确定应该实例化对应类层次结构中的哪个类，从而将行层次结构中的子类对应起来。此模式采用了泛型和反射技术。
4.参考：http://haolloyin.blog.51cto.com/1177454/332576/