为什么Service继承自Android中的Context？

Question

我正在研究 Javadoc 并注意到了这一点：

java.lang.Object
    android.content.Context
        android.content.ContextWrapper
            android.app.Service

因此，在 Android 中，Service 似乎继承自 Context！

但这是什么意思呢？它们对我来说是完全不同的概念。

Answer 1

Service 和 Activity 都继承自 Context。来自 Android 文档： "The Context 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."

与 Activity 一样，服务 class 需要能够获取资源并启动活动并执行所有需要访问应用程序级别 class 的事情。实际上，服务很像 Activity，只是没有 UI 元素。

Answer 2

官方 android 文档描述 Context:

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.

和Service作为

A Service is an application component representing either an application's desire to perform a longer-running operation while not interacting with the user or to supply functionality for other applications to use.

context其实是一个广义的称呼，在具体使用的时候可能会比较难理解。您可能想查看一个很好的解释 here.

服务从对象的继承可能更清楚，只是想象上下文是介于它们之间的东西，只是不像对象那么抽象。

为什么Service继承自Android中的Context？

Why Service inherits from Context in Android?

java

android

android-service

android-context