工厂+策略--》简单使用

先看以下范例：

public class Promotions {
    public static void main(String[] args) {
        Integer price=getPrice(3,1000);
        System.out.println(price);
    }

    /**
     * 不同的数字代表不同的打折方式
     * @param num
     * @param totalPrice
     * @return
     */
    private static Integer getPrice(int num, int totalPrice) {
        Integer price=0;
        switch (num){
            case 1:
                price=getOneZhePrice(totalPrice);
                break;
            case 2:
                price=getTwoZhePrice(totalPrice);
                break;
            case 3:
                price=getThreeZhePrice(totalPrice);
                break;
            default:
                price=totalPrice;
        }
        return price;
    }

    private static Integer getThreeZhePrice(int totalPrice) {
        return totalPrice*30;
    }

    private static Integer getTwoZhePrice(int totalPrice) {
        return totalPrice*20;
    }

    private static Integer getOneZhePrice(int totalPrice) {
        return totalPrice*10;
    }
}

加入策略类，每种打折的实现在自己的策略类实现,定义计算价格的总策略类，具体的策略类继承总抽象类：

public abstract class CalculationPrice {

    //定义获取价格的方法
    public abstract Integer getPrice(Integer totalPrice);
}

public class OneCalculation extends CalculationPrice {
    @Override
    public Integer getPrice(Integer totalPrice) {
        return totalPrice*1;
    }
}

public class TwoCalculation extends CalculationPrice {
    @Override
    public Integer getPrice(Integer totalPrice) {
        return totalPrice*2;
    }
}

public class ThreeCalculation extends  CalculationPrice{
    @Override
    public Integer getPrice(Integer totalPrice) {
        return totalPrice*3;
    }
}

public class Promotions {
    public static void main(String[] args) {
        Integer price=getPrice(1,1000);
        System.out.println(price);
    }

    /**
     * 不同的数字代表不同的打折方式
     * @param num
     * @param totalPrice
     * @return
     */
    private static Integer getPrice(int num, int totalPrice) {

        CalculationPrice calculationPrice=null;

        switch (num){
            case 1:
                calculationPrice=new OneCalculation();
                break;
            case 2:
                calculationPrice=new TwoCalculation();
                break;
            case 3:
                calculationPrice=new ThreeCalculation();
                break;
            default:
                calculationPrice=new OneCalculation();
        }
        return calculationPrice.getPrice(totalPrice);
    }

    /*private static Integer getThreeZhePrice(int totalPrice) {
        return totalPrice*30;
    }

    private static Integer getTwoZhePrice(int totalPrice) {
        return totalPrice*20;
    }

    private static Integer getOneZhePrice(int totalPrice) {
        return totalPrice*10;
    }*/
}

加入工厂类：

public class PromotionsFactory {

    //根据不同的策略获取不同的策略类
    public static CalculationPrice getCalculationPrice(Integer integer){
        CalculationPrice calculationPrice=null;

        switch (integer){
            case 1:
                calculationPrice=new OneCalculation();
                break;
            case 2:
                calculationPrice=new TwoCalculation();
                break;
            case 3:
                calculationPrice=new ThreeCalculation();
                break;
            default:
                calculationPrice=new OneCalculation();
        }
        return calculationPrice;
    }
}

public class Promotions {
    public static void main(String[] args) {
        Integer price=getPrice(1,1000);
        System.out.println(price);
    }

    /**
     * 不同的数字代表不同的打折方式
     * @param num
     * @param totalPrice
     * @return
     */
    private static Integer getPrice(int num, int totalPrice) {
        CalculationPrice calculationPrice = PromotionsFactory.getCalculationPrice(num);
        return calculationPrice.getPrice(totalPrice);

        /*CalculationPrice calculationPrice=null;

        switch (num){
            case 1:
                calculationPrice=new OneCalculation();
                break;
            case 2:
                calculationPrice=new TwoCalculation();
                break;
            case 3:
                calculationPrice=new ThreeCalculation();
                break;
            default:
                calculationPrice=new OneCalculation();
        }
        return calculationPrice.getPrice(totalPrice);*/
    }

    /*private static Integer getThreeZhePrice(int totalPrice) {
        return totalPrice*30;
    }

    private static Integer getTwoZhePrice(int totalPrice) {
        return totalPrice*20;
    }

    private static Integer getOneZhePrice(int totalPrice) {
        return totalPrice*10;
    }*/
}