Android官方文档翻译 十六 4.Managing the Activity Lifecycle

Managing the Activity Lifecycle

管理activity的生命周期

Dependencies and prerequisites

依赖关系和先决条件

• How to create an Android project (see Creating an Android Project)

  如何创建一个Android项目（请看Creating an Android Project）

You should also read

你还需要阅读

• Activities

As a user navigates through, out of, and back to your app, the Activity instances in your app transition between different states in their lifecycle. For instance, when your activity starts for the first time, it comes to the foreground of the system and receives user focus. During this process, the Android system calls a series of lifecycle methods on the activity in which you set up the user interface and other components. If the user performs an action that starts another activity or switches to another app, the system calls another set of lifecycle methods on your activity as it moves into the background (where the activity is no longer visible, but the instance and its state remains intact).

随着用户通过导航在你的应用程序中来来回回，你的应用程序中的activity实体也在它们的声明周期中进行着不同的状态转换。对于一个实体，当你的activity第一次开启的时候，它会出现在你系统的前台并且可以接受用户的焦点。在这个过程中，Android系统会调用activity中一系列的生命周期方法，那里有你设置的用户界面以及其它的一些组件。如果用户执行了一个动作来开启另一个activity或者选择了另一个应用程序，系统会在你的应用程序进入后台的时候调用你的activity中的其它的一些生命周期方法（此时activity不再可见，但是实体和它的状态依然保持完整）。

Within the lifecycle callback methods, you can declare how your activity behaves when the user leaves and re-enters the activity. For example, if you’re building a streaming video player, you might pause the video and terminate the network connection when the user switches to another app. When the user returns, you can reconnect to the network and allow the user to resume the video from the same spot.

当用户离开或者再次进入一个activity时，你可以在生命周期回调方法中，生命你的activity应该如何运转。例如：如果你创建了一个流媒体播放器，当用户选择调到另一个应用程序中，你可能需要暂停视频播放并且结束网络连接。当用户重新返回的时候，你可能要再次连接网络并且允许用户从原来的节点从新开始播放视频。

This class explains important lifecycle callback methods that each Activity instance receives and how you can use them so your activity does what the user expects and does not consume system resources when your activity doesn’t need them.

这节课会解释对于每个activity实体都会接收的重要的生命周期回调方法，还有你要如何使用它们去让你的activity做用户期待它做的事情，以及当你的activity不需要它们的时候怎样才不会消耗系统资源。

Lessons

课程

Starting an Activity

开启一个activity

Learn the basics about the activity lifecycle, how the user can launch your app, and how to perform basic activity creation.

学习关于生命周期的基础，如何让用户启动你的应用程序以及如何执行基本的activity创建。

Pausing and Resuming an Activity

暂停和恢复一个activity

Learn what happens when your activity is paused (partially obscured) and resumed and what you should do during these state changes.

学习当activity暂停(局部隐藏)和恢复的时候会发生什么，以及在这些状态改变期间你应该做什么。

Stopping and Restarting an Activity

停止和重启一个activity

Learn what happens when the user completely leaves your activity and returns to it.

学习当用户完全离开以及重新返回你的activity的时候会发生什么。

Recreating an Activity

重新创建一个activity

Learn what happens when your activity is destroyed and how you can rebuild the activity state when necessary.

学习当activity被销毁的时候会发生什么，还有当必要的时候你如何重新构建此activity的状态。

Get started

让我们开始吧

这是我自己翻译的，如果您发现其中有重要错误，敬请指出，万分感谢！