策略模式（Strategy）

 

以商场打折为例

package Strategy;

public abstract class CashSuper {
	protected abstract Double acceptCash(Double money);
}



package Strategy;

/**
 * 正常收费
 * @author Modun
 *
 */
public class CashNormal extends CashSuper{
	@Override
	protected Double acceptCash(Double money) {
		
		return money;
	}

}



package Strategy;

/**
 * 打折收费
 * @author Modun
 *
 */
public class CashRebate extends CashSuper{
	private double rebate;
	
	public CashRebate(Double rebate){
		this.rebate = rebate;
	}
	
	@Override
	protected Double acceptCash(Double money) {
		return money * rebate;
	}

}



package Strategy;

/**
 * 满多少返多少收费
 * @author Modun
 *
 */
public class CashReturn extends CashSuper{
	private Double moneyCondition;
	private Double moneyReturn;
	
	public CashReturn(Double moneyCondition, Double moneyReturn){
		this.moneyCondition = moneyCondition;
		this.moneyReturn = moneyReturn;
	}
	
	@Override
	protected Double acceptCash(Double money) {
		if (money >= moneyCondition) {
			return money - (moneyReturn * Math.floor((money / moneyCondition)));
		}
		return money;
	}
	
}



package Strategy;

public class CashContext {
	private CashSuper cs;
	
	public CashContext(String type){
		if (type.equals("正常")) {
			cs = new CashNormal();
		}else if(type.equals("8折")){
			cs = new CashRebate(0.8);
		}else if(type.equals("满300减100")){
			cs = new CashReturn(300.0, 100.0);
		}else{
			throw new IllegalArgumentException("不支持的促销方式");
		}
	}
	
	public Double getResult(Double money){
		return cs.acceptCash(money);
	}
}



package Strategy;

public class Program {
	public static void main(String[] args) {
		CashContext c1 = new CashContext("正常");
		CashContext c2 = new CashContext("8折");
		CashContext c3 = new CashContext("满300减100");
		
		System.out.println("总价格为400元，您应付款：" + c1.getResult(400.0));
		System.out.println("总价格为400元，您应付款：" + c2.getResult(400.0));
		System.out.println("总价格为400元，您应付款：" + c3.getResult(400.0));
		System.out.println("总价格为600元，您应付款：" + c3.getResult(600.0));
	}
}