java_IO_装饰器

装饰器模式

装饰器模式（Decorator Pattern）允许向一个现有的对象添加新的功能，同时又不改变其结构。这种类型的设计模式属于结构型模式，它是作为现有的类的一个包装。

这种模式创建了一个装饰类，用来包装原有的类，并在保持类方法签名完整性的前提下，提供了额外的功能。

package ioStudy;


/**
 * 装饰器模式
 * 1.抽象接口
 * 2.具体对象
 * 3.抽象装饰者
 * 4.具体装饰者
 * */
public class DecorateStudy1 {
    
    public static void main(String[] args) {
        Drink coffee = new Coffee();
        
        Decorate milk = new Milk(coffee);
        System.out.println(milk.info()+"===>"+milk.cost());
        
        Decorate sugar = new Sugar(coffee);
        System.out.println(sugar.info()+"===>"+sugar.cost());
        
        milk = new Milk(sugar);
        System.out.println(milk.info()+"===>"+milk.cost());
    }
}


interface Drink {
    String info();
    int cost();
}

class Coffee implements Drink{
    
    private String name = "原味咖啡";
    private int price = 10;

    @Override
    public String info() {
        // TODO Auto-generated method stub
        return name;
    }

    @Override
    public int cost() {
        // TODO Auto-generated method stub
        return price;
    }
}

abstract class Decorate implements Drink {
    Drink drink;
    public Decorate(Drink drink) {
        this.drink = drink;
    }
    
    public String info() {
        return drink.info();
    }
    
    public int cost() {
        return drink.cost();
    }
}

class Milk extends Decorate{

    public Milk(Drink drink) {
        super(drink);
    }
    
    public String info() {
        return super.drink.info() + "加入了牛奶";
    }
    
    public int cost() {
        return super.drink.cost()*4;
    }
}

class Sugar extends Decorate{

    public Sugar(Drink drink) {
        super(drink);
    }
    
    public String info() {
        return super.drink.info() + "加入了方糖";
    }
    
    public int cost() {
        return super.drink.cost()*3;
    }
}

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用BufferedInputStream  BufferedOutputStream  BufferedReader  BufferWriter  包装其他输入输出流  能够提升读写速度。

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