Decorator pattern

文章:

1、geeksforgeeks-The-Decorator-Pattern

结合具体的案例，非常好

2、wikipedia-Decorator-pattern

比较冗杂，论述很多

Composition over inheritance: decorator is an alternative to subclassing

一、最能够体现"decorator is an alternative to subclassing"的例子是: geeksforgeeks Decorator Pattern | Set 1 (Background) 、 geeksforgeeks The Decorator Pattern | Set 2 (Introduction and Design) 中给出的pizza + topping的例子:

geeksforgeeks Decorator Pattern | Set 1 (Background) 中，使用subclassing ，并分析了它的disadvantage， geeksforgeeks The Decorator Pattern | Set 2 (Introduction and Design) 使用decorator来进行改进，可以看到，使用decorator非常灵活、扩展性非常好

二、在 wikipedia Decorator pattern 中，对这个topic进行了总结。

Use case

解决Combination explode、an alternative to subclassing

这是Decorator pattern能够很好的解决的问题，example:

1、geeksforgeeks-The-Decorator-Pattern 中的pizza+topping例子

Pipeline multiple layer、流程、chain composition

其实这也是combination，不同的是它还添加了流程、multiple layer，example:

1、wikipedia Decorator pattern 中的 class WebPage 例子

Protocol interceptor(拦截器)

1、apache HttpClient Tutorial # 1.4. HTTP protocol interceptors

The HTTP protocol interceptor(拦截器) is a routine that implements a specific aspect of the HTTP protocol. Usually protocol interceptors are expected to act upon one specific header or a group of related headers of the incoming message, or populate the outgoing message with one specific header or a group of related headers. Protocol interceptors can also manipulate content entities enclosed with messages - transparent content compression / decompression being a good example. Usually this is accomplished by using the 'Decorator' pattern where a wrapper entity class is used to decorate the original entity. Several protocol interceptors can be combined to form one logical unit.

2、我的工程中也使用了

TODO

1、sourcemaking Decorator Design Pattern

2、refactoring Decorator