[安卓基础] 007.管理Activity的生命周期

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管理Activity的生命周期

序言

从这章开始，我们会用这几节课程来学习Activity的生命周期机制。

1、开启（start）Activity
2、暂停（pause）和恢复（resume）Activity
3、停止（stop）和重新打开（restart）Activity
4、重新创建（recreate）Activity

我们知道一个app会由许多Activity和其他组件组成。这里暂时只介绍Activity。当我们在手机上玩一款app时，app的Activity们就会被启动或者退出，在启动或退出的过程中，Activity会进入不同的生命周期状态。举一个例子：当一个Activity第一次被启动的时候，它会被推送到屏幕的最前端并获取到用户的操作焦点（就是能响应用户点击屏幕的操作）。在这样的过程中，安卓系统会调用这个Activity的一系列的生命周期方法。当你打开另一个Activity或者打开另一个应用的时候，安卓系统又会调用另一个Activity的生命周期并把上一个Activity放置在系统后端（虽然这个Activity看不见了，但它暂时被保存在后台，除非系统内存不足会被收回，不然它还是保存着刚才的状态的。）

在这一系列的生命周期回调方法中，你可也在这些方法里编写代码来告诉Activity在这些生命周期里，需要做的事情。例如：当你正在看视频的时候，突然一个电话进来，你就需要让这个视频Activity去记录视频播放的位置并暂停视频，而当电话结束的时候，你要让视频继续重新连上网络继续从刚才暂停的地方继续播放。

本站文章为宝宝巴士 SD.Team原创，转载务必在明显处注明：（作者官方网站：宝宝巴士) 
转载自【宝宝巴士SuperDo团队】 原文链接: http://www.cnblogs.com/superdo/p/4625496.html