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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