Context

一直对Context有疑惑。官方解释：

public abstract class 
Context
extends Object

Class Overview

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.

一个应用环境的全局信息接口，它是一个抽象类由系统来实现。它允许访问应用程序特定的资源和类，以及向上调用应用级操作例如启动activity，broadcasting，和接收intents组件。