java23中设计模式之策略模式

Posted 2020-10-08 周无极

package com.bjsxt.strategy;

/**
 * 负责和具体的策略类交互
 * 这样的话，具体的算法和直接的客户端调用分离了，使得算法可以独立于客户端独立的变化。
 * 如果使用spring的依赖注入功能，还可以通过配置文件，动态的注入不同策略对象，动态的切换不同的算法.
 * @author Administrator
 *
 */
public class Context {
    private Strategy strategy;    //当前采用的算法对象

    //可以通过构造器来注入
    public Context(Strategy strategy) {
        super();
        this.strategy = strategy;
    }
    //可以通过set方法来注入
    public void setStrategy(Strategy strategy) {
        this.strategy = strategy;
    }
    
    public void pringPrice(double s){
        System.out.println("您该报价："+strategy.getPrice(s));
    }
    
    
}

context

Strategy.java

strategy

package com.bjsxt.strategy;

public class NewCustomerFewStrategy implements Strategy {

    public double getPrice(double standardPrice) {
        System.out.println("不打折，原价");
        return standardPrice;
    }

}

NewCustomerFewStrategy

package com.bjsxt.strategy;

public class NewCustomerManyStrategy implements Strategy {

    public double getPrice(double standardPrice) {
        System.out.println("打九折");
        return standardPrice*0.9;
    }

}

NewCustomerManyStrategy

package com.bjsxt.strategy;

public class OldCustomerFewStrategy implements Strategy {

    public double getPrice(double standardPrice) {
        System.out.println("打八五折");
        return standardPrice*0.85;
    }

}

OldCustomerFewStrategy

package com.bjsxt.strategy;

public class OldCustomerManyStrategy implements Strategy {

    public double getPrice(double standardPrice) {
        System.out.println("打八折");
        return standardPrice*0.8;
    }

}

OldCustomerManyStrategy

package com.bjsxt.strategy;

public class Client {
    public static void main(String[] args) {
        
        Strategy s1 = new OldCustomerManyStrategy();
        Context ctx = new Context(s1);
        
        ctx.pringPrice(998);
        
    }
}

Client

package com.bjsxt.strategy;

/**
 * 实现起来比较容易，符合一般开发人员的思路
 * 假如，类型特别多，算法比较复杂时，整个条件语句的代码就变得很长，难于维护。
 * 如果有新增类型，就需要频繁的修改此处的代码！
 * 不符合开闭原则！
 * @author Administrator
 *
 */
public class TestStrategy {
    public double getPrice(String type, double price) {

        if (type.equals("普通客户小批量")) {
            System.out.println("不打折,原价");
            return price;
        } else if (type.equals("普通客户大批量")) {
            System.out.println("打九折");
            return price * 0.9;
        } else if (type.equals("老客户小批量")) {
            System.out.println("打八五折");
            return price * 0.85;
        } else if (type.equals("老客户大批量")) {
            System.out.println("打八折");
            return price * 0.8;
        }
        return price;
    }

}

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