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。

 1 package ioStudy;
 2 
 3 
 4 /**
 5  * 装饰器模式
 6  * 1.抽象接口
 7  * 2.具体对象
 8  * 3.抽象装饰者
 9  * 4.具体装饰者
10  * */
11 public class DecorateStudy1 {
12     
13     public static void main(String[] args) {
14         Drink coffee = new Coffee();
15         
16         Decorate milk = new Milk(coffee);
17         System.out.println(milk.info()+"===>"+milk.cost());
18         
19         Decorate sugar = new Sugar(coffee);
20         System.out.println(sugar.info()+"===>"+sugar.cost());
21         
22         milk = new Milk(sugar);
23         System.out.println(milk.info()+"===>"+milk.cost());
24     }
25 }
26 
27 
28 interface Drink {
29     String info();
30     int cost();
31 }
32 
33 class Coffee implements Drink{
34     
35     private String name = "原味咖啡";
36     private int price = 10;
37 
38     @Override
39     public String info() {
40         // TODO Auto-generated method stub
41         return name;
42     }
43 
44     @Override
45     public int cost() {
46         // TODO Auto-generated method stub
47         return price;
48     }
49 }
50 
51 abstract class Decorate implements Drink {
52     Drink drink;
53     public Decorate(Drink drink) {
54         this.drink = drink;
55     }
56     
57     public String info() {
58         return drink.info();
59     }
60     
61     public int cost() {
62         return drink.cost();
63     }
64 }
65 
66 class Milk extends Decorate{
67 
68     public Milk(Drink drink) {
69         super(drink);
70     }
71     
72     public String info() {
73         return super.drink.info() + "加入了牛奶";
74     }
75     
76     public int cost() {
77         return super.drink.cost()*4;
78     }
79 }
80 
81 class Sugar extends Decorate{
82 
83     public Sugar(Drink drink) {
84         super(drink);
85     }
86     
87     public String info() {
88         return super.drink.info() + "加入了方糖";
89     }
90     
91     public int cost() {
92         return super.drink.cost()*3;
93     }
94 }

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