什么是包装器类? 这样的类有什么用处呢?
当前回答
有几种设计模式可以称为包装器类。
请参阅我对“代理、装饰器、适配器和桥接模式有何不同?”
其他回答
一个包装类不一定需要包装另一个类。它可能是一个API类,在一个dll文件中包装功能。
例如,创建一个dll包装类可能非常有用,它负责所有dll的初始化和清理,并创建类方法来包装从GetProcAddress()创建的函数指针。
干杯!
In general, a wrapper class is any class which "wraps" or "encapsulates" the functionality of another class or component. These are useful by providing a level of abstraction from the implementation of the underlying class or component; for example, wrapper classes that wrap COM components can manage the process of invoking the COM component without bothering the calling code with it. They can also simplify the use of the underlying object by reducing the number interface points involved; frequently, this makes for more secure use of underlying components.
有几种设计模式可以称为包装器类。
请参阅我对“代理、装饰器、适配器和桥接模式有何不同?”
包装类是一个“包装”其他东西的类,就像它的名字一样。
它更正式的定义是实现适配器模式的类。这允许您将一组api修改为更可用、更可读的形式。例如,在c#中,如果你想使用本机Windows API,它有助于将它包装成一个符合. net设计准则的类。
值得注意的是,在某些环境中,包装器类所做的大部分工作都被方面所取代。
编辑:
一般来说,包装器将对包装所做的事情进行扩展,而不关心包装的实现,否则,包装与扩展被包装的类没有任何意义。一个典型的例子是围绕一些其他服务接口添加计时信息或日志功能,而不是将其添加到该接口的每个实现中。
This then ends up being a typical example for Aspect programming. Rather than going through an interface function by function and adding boilerplate logging, in aspect programming you define a pointcut, which is a kind of regular expression for methods, and then declare methods that you want to have executed before, after or around all methods matching the pointcut. Its probably fair to say that aspect programming is a kind of use of the Decorator pattern, which wrapper classes can also be used for, but that both technologies have other uses.