A Command is a function object in its purest sense: a method
that’s an object
.
By wrapping a method in an object, you can pass it to other methods or objects
as a parameter, to tell them to perform this particular operation in the process
of fulfilling your request. You could say that a Command
is a messenger
(because its intent and use is very straightforward) that carries behavior,
rather than data.
......
The primary point of Command
is to allow you to hand a desired action to
a method or object. In the above example, this provides a way to queue a set of
actions to be performed collectively. In this case, it allows you to dynamically
create new behavior, something you can normally only do by writing new code
but
in the above example could be done by interpreting a script (see the
Interpreter
pattern if what you need to do gets very complex).
以上描述是对Command设计模式的很好阐述,正如题目中Command设计模式就是在运行中选择“operation”,只要将“opration”按照自己的需求,实现接口就可以了,达到了调用方和“operation”解耦的目的。
具体的应用学习,在http://lgd-java2eye.iteye.com/blog/757524
中有很好的解释,这里不赘述。
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