The service provider state can be passed to the service requester directly in the event parameter of the update() method rather than as a separate call to getState().

服务提供者的状态可以作为 update() 方法的参数，直接传递给服务请求者，而不是单独调用 getState() 方法来获得服务提供者的状态。

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This method is necessary if your manager implementation maintains separate listeners lists based on information that is captured in the event data.

如果管理器实现根据事件数据中捕获的信息维护单独的侦听器列表，则此方法是必需的。

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For example, a button-click event and a menu-command-click event can both invoke the same delegate, which then calls a single method to handle these separate events the same way.

例如，单击按钮事件和单击菜单命令事件都能调用同一委托，然后该委托调用单个方法以相同方式处理各个事件。

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