大三打卡（10.10）

实验 25：访问者模式

本次实验属于模仿型实验，通过本次实验学生将掌握以下内容：

1、理解访问者模式的动机，掌握该模式的结构；

2、能够利用访问者模式法解决实际问题。

 

[实验任务一]：打包员

在我们课堂上的“购物车”的例子中，增加一个新的访问者：打包员，负责对购物车中货物装包。

实验要求：

1.  画出对应的类图；

 

2.  提交源代码；

package RJSJ.test25;

 

public class Apple implements Product {

    @Override

    public void accept(Visitor visitor) {

        visitor.visit(this);

    }

}

package RJSJ.test25;

 

public class Book implements Product{

    @Override

    public void accept(Visitor visitor) {

        visitor.visit(this);

    }

}

 

package RJSJ.test25;

 

import java.util.ArrayList;

import java.util.List;

 

public class BuyBasket {

 

    private List<Product> products = new ArrayList();

 

    public void accept(Visitor visitor) {

        for (Product product : products) {

            product.accept(visitor);

        }

    }

 

    public void addProduct(Product p) {

        products.add(p);

    }

 

    public void removeProduct(Product p) {

        products.remove(p);

    }

}

package RJSJ.test25;

 

public class Client {

 

    public static void main(String[] args) {

        BuyBasket buyBasket = new BuyBasket();

 

        buyBasket.addProduct(new Apple());

        buyBasket.addProduct(new Book());

 

        Visitor saler = new Saler();

        saler.setName("张三");

 

        buyBasket.accept(saler);

 

        Visitor packer = new Packer();

        packer.setName("李四");

 

        buyBasket.accept(packer);

 

        Visitor customer = new Customer();

        customer.setName("王五");

 

        buyBasket.accept(customer);

    }

}

package RJSJ.test25;

 

public class Customer extends Visitor {

    @Override

    public void visit(Apple apple) {

        System.out.println("顾客" + name + "选苹果");

    }

 

    @Override

    public void visit(Book book) {

        System.out.println("顾客" + name + "买书");

    }

}

package RJSJ.test25;

 

public class Packer extends Visitor {

    @Override

    public void visit(Apple apple) {

        System.out.println("打包员" + name + "给苹果打包");

    }

 

    @Override

    public void visit(Book book) {

        System.out.println("打包员" + name + "给书打包");

    }

}

package RJSJ.test25;

 

public interface Product {

 

    void accept(Visitor visitor);

}

package RJSJ.test25;

 

 

public class Saler extends Visitor {

    @Override

    public void visit(Apple apple) {

        System.out.println("收银员" + name + "给苹果过秤，然后计算其价格");

    }

 

    @Override

    public void visit(Book book) {

        System.out.println("收银员" + name + "直接计算书的价格");

 

    }

}

package RJSJ.test25;

 

public abstract class Visitor {

    protected String name;

 

    public void setName(String name) {

        this.name = name;

    }

 

    public abstract void visit(Apple apple);

 

    public abstract void visit(Book book);

 

}