Components are most commonly found within the core class that defines the entities in a game, but they may be useful in other places as well. This pattern can be put to good use when any of these are true:

- You have a class that touches multiple domains which you want to keep decoupled from each other.

- A class is getting massive and hard to work with.

- You want to be able to define a variety of objects that share different capabilities, but using inheritance doesn’t let you pick the parts you want to reuse precisely enough.

组件最常见于游戏中定义实体的核心类，但是它们也能够用在别的地方。当如下条件成立时，组件模式就能够发挥它的作用：