Context部分译(http://developer.android.com/reference/android/content/Context.html))

Class Overview

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Interface to global information about an application environment.  This is an abstract class whose implementation is provided by the Android system.  It allows access to application-specific resources and classes, as well as up-calls for application-level operations such as launching activities, broadcasting and receiving intents, etc.

应用环境全局信息的接口。这是一个抽象类，由android系统对其提供实现方法。它让你可以得到应用程序的详细的资源和类，并且能上升到应用程序级的调用操作，如启动应用程序，广播，接受intent等等。