实例：商店促销

(1)首先考虑用简单工厂模式进行设计

Ø  客户端代码Main.java

package com.yilong.sell.factory;

public class Main {

public static void main(String[] args) {

//SellMethod sellMethod = SellMethodFactory.create("原价");

SellMethod sellMethod = SellMethodFactory.create("方案一");

if(sellMethod != null) {

sellMethod.setPrePrice(10);

sellMethod.setAmount(10);

System.out.println("总价：" + sellMethod.getSumPrice());

} else {

System.out.println("暂未定义该销售方案！");

}

}

}

Ø  促销形式类 SellMethod.java

package com.yilong.sell.factory;

public abstract class SellMethod {

private double prePrice;

private int amount;

public abstract double getSumPrice();

public int getAmount() {

return amount;

}

public void setAmount(int amount) {

this.amount = amount;

}

public double getPrePrice() {

return prePrice;

}

public void setPrePrice(double prePrice) {

this.prePrice = prePrice;

}

}

Ø  原价销售实现类 SellMethodPrototype.java

package com.yilong.sell.factory;

public class SellMethodPrototype extends SellMethod {

@Override

public double getSumPrice() {

return this.getPrePrice() * this.getAmount();

}

}

Ø  打折销售实现类 SellMethodDiscount.java

package com.yilong.sell.factory;

public class SellMethodDiscount extends SellMethod {

public static final double DISCOUNT = 0.5;

@Override

public double getSumPrice() {

return this.getPrePrice() * this.getAmount() * this.DISCOUNT;

}

}

Ø  销售方法生产类 SellMethodFactory.java

package com.yilong.sell.factory;

public class SellMethodFactory {

public static SellMethod create(String method) {

SellMethod sellMethod = null;

if(method.equals("原价")) {

sellMethod = new SellMethodPrototype();

} else if(method.equals("方案一")){

sellMethod = new SellMethodDiscount();

}

return sellMethod;

}

}

(2)然后考虑用策略模式实现

Ø  客户端代码 Main.java

package com.yilong.sell.strategy;

public class Main {

public static void main(String[] args) {

SellGood sellGood = new SellGood("打5折");

sellGood.setPrePrice(10);

sellGood.setAmount(10);

System.out.println("总价：" + sellGood.getSumPrice());

}

}

Ø  销售方式类 SellMethod.java

package com.yilong.sell.strategy;

public abstract class SellMethod {

public abstract double getSumPrice(double prePrice, int amount);

}

Ø  原价销售类 SellMethodPrototype.java

package com.yilong.sell.strategy;

public class SellMethodPrototype extends SellMethod {

@Override

public double getSumPrice(double prePrice, int amount) {

return prePrice * amount;

}

}

Ø  打折销售类 SellMethodDiscount.java

package com.yilong.sell.strategy;

public class SellMethodDiscount extends SellMethod {

public static final double DISCOUNT = 0.5;

@Override

public double getSumPrice(double prePrice, int amount) {

return prePrice * amount *