Android 源码分析Application的生命周期及共享数据详解

推荐阅读：

Android 深刻理解Activity生命周期的作用及意义

一、概述

Application源码介绍，如下所示：

/**
 * Base class for maintaining global application state. You can provide your own
 * implementation by creating a subclass and specifying the fully-qualified name
 * of this subclass as the <code>"android:name"</code> attribute in your
 * AndroidManifest.xml's <code><application></code> tag. The Application
 * class, or your subclass of the Application class, is instantiated before any
 * other class when the process for your application/package is created.
 *
 * <p class="note"><strong>Note: </strong>There is normally no need to subclass
 * Application.  In most situations, static singletons can provide the same
 * functionality in a more modular way.  If your singleton needs a global
 * context (for example to register broadcast receivers), include
 * {@link android.content.Context#getApplicationContext() Context.getApplicationContext()}
 * as a {@link android.content.Context} argument when invoking your singleton's
 * <code>getInstance()</code> method.
 * </p>
 */

概述：

     Application类是为了那些需要保存全局变量设计的基本类，你可以在AndroidManifest.xml的<application>标签中通过"android:name"属性进行使用，自定义的application作为基类会影响该程序中每个类的建立，只需要调用Context的getApplicationContext或者Activity的getApplication方法来获得一个application对象，就能做出相应的处理。

二、程序生命周期

1、onCreate():