Whether you hang onto this reference or not is up to you, because the WatchService returns the relevant WatchKey to you when an event is triggered.

是否挂接到这个引用由您决定，因为触发事件后，WatchService 会返回相关的 WatchKey。

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When you're done with a particular WatchKey and the events it's registered for, you can cancel its registration with the WatchService simply by calling its cancel method.

当您在处理特定WatchKey及其所注册的事件时，可以很简单地通过调用cancel方法，来取消其在WatchService的注册。

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