java设计模式-策略模式(九)

package com.utstar.pattern.strategy;

/**
 * 策略算法统一接口
 * @author HZ20232
 *
 */
public interface Strategy {
    public double calculate(double old);
}


package com.utstar.pattern.strategy;

/**
 * 策略算法的一个实现
 * @author HZ20232
 *
 */
public class NormalCustomer implements Strategy{
    
    public double calculate(double old){
        System.out.println("普通用户一律99折");
        return old*0.99;
    }
}

package com.utstar.pattern.strategy;
/**
 * 另一个实现
 * @author HZ20232
 *
 */
public class OldCustmer implements Strategy{
    public double calculate(double old){
        System.out.println("老用户一律5折");
        return old*0.5;
    }
}

package com.utstar.pattern.strategy;

public class BigCustmer implements Strategy{
    public double calculate(double old){
        System.out.println("大客户一律1折");
        return old*0.1;
    }
}

package com.utstar.pattern.strategy;

/**
 *
 * @author HZ20232
 *
 */
public class Price{
    private Strategy method;
    
    public Price(Strategy s){
        this.method = s;
    }
    public void setMethod(Strategy s){
        this.method = s;
    }
    public double getPrice(double old){
        return this.method.calculate(old);
    }
}

package com.utstar.pattern.strategy;

/**
 * 策略模式，当ifelse比较多的时候可以考虑用策略模式，其各种策略算法是平行关系，没有归属关系
 * java是面向接口编程，在考虑设计的时候优先考虑接口，其次当有对公用功能进行规定的时候考虑抽象类
 * @author HZ20232
 *
 */
public class TestStrategy{
    public static void main(String args[]){
        Strategy normal = new NormalCustomer();
        
        Price context = new Price(normal);
        double old = 100;
        double normalPrice = context.getPrice(old);
        System.out.println(normalPrice);
        
        Strategy oldCustmer = new OldCustmer();
        
        context.setMethod(oldCustmer);
        double oldPrice = context.getPrice(old);
        System.out.println(oldPrice);
        
        Strategy bigCustmer = new BigCustmer();
        
        context.setMethod(bigCustmer);
        double bigPrice = context.getPrice(old);
        System.out.println(bigPrice);
    }
}