简单工厂模式

简单工厂模式将对象的实例方法了工厂中创造，程序比较简单，只是将原本应该出现在客户程序的判断放到了工厂中，参照《Head First》的例子，有一个PizzaStore卖各种口味的Pizza。

//PizzaStore 它的orderPizza只返回一个抽象的Pizza，而具体的实例交有工厂去处理

package Factory.SimpleFactory;

/**
 * Created by sgzhang on 2015/8/12.
 */
public class PizzaStore {
    public Pizza orderPizza(String type){
        Pizza pizza=(new SimpleFactory()).createPizza(type);
        return pizza;
    }

    public static void main(String[] args){
        PizzaStore pizzaStore=new PizzaStore();
        Pizza pizza1= pizzaStore.orderPizza("Cheese");
        Pizza pizza2= pizzaStore.orderPizza("Greek");
        Pizza pizza3= pizzaStore.orderPizza("Hot");
        pizza1.eat();
        pizza2.eat();
        pizza3.eat();
    }
}

//SimpleFactory

package Factory.SimpleFactory;

/**
 * Created by sgzhang on 2015/8/12.
 */
public class SimpleFactory {
    public Pizza createPizza(String type){
        Pizza pizza=null;
        if(type.equals("Cheese")){
            pizza=new CheesePizza();
        }else if(type.equals("Greek")){
            pizza=new GreekPizza();
        }else{
            pizza=new HotPizza();
        }
        return  pizza;
    }
}

//所有Pizza的父类，这里只有一个eat方法

package Factory.SimpleFactory;

/**
 * Created by sgzhang on 2015/8/12.
 */
public abstract class Pizza {
    abstract void eat();
}

//CheesePizza

package Factory.SimpleFactory;

/**
 * Created by sgzhang on 2015/8/12.
 */
public class CheesePizza extends Pizza {
    @Override
    void eat() {
        System.out.println("CheesePizza");
    }
}

//GreekPizza

package Factory.SimpleFactory;

/**
 * Created by sgzhang on 2015/8/12.
 */
public class GreekPizza extends Pizza{
    @Override
    void eat() {
        System.out.println("GreekPizza");
    }
}

//HotPizza

package Factory.SimpleFactory;

/**
 * Created by sgzhang on 2015/8/12.
 */
public class HotPizza extends Pizza{
    @Override
    void eat() {
        System.out.println("HotPizza");
    }
}

//工厂负责逻辑判断

package Factory.SimpleFactory;

/**
 * Created by sgzhang on 2015/8/12.
 */
public class SimpleFactory {
    public Pizza createPizza(String type){
        Pizza pizza=null;
        if(type.equals("Cheese")){
            pizza=new CheesePizza();
        }else if(type.equals("Greek")){
            pizza=new GreekPizza();
        }else{
            pizza=new HotPizza();
        }
        return  pizza;
    }
}