Android Activity 源码解析

2015/03/22 技术分享

Android Activity 源码解析

Activity 是用得最多的了,平时也只是熟练的使用,知道 launchMode、intent-filte、screenOrientation,然后看下官网的资料,7个步骤,如何切换这些。现在就读一下底层的源码吧。


  * <p>Topics covered here:
 * <ol>
 * <li><a href="#Fragments">Fragments</a>
 * <li><a href="#ActivityLifecycle">Activity Lifecycle</a>
 * <li><a href="#ConfigurationChanges">Configuration Changes</a>
 * <li><a href="#StartingActivities">Starting Activities and Getting Results</a>
 * <li><a href="#SavingPersistentState">Saving Persistent State</a>
 * <li><a href="#Permissions">Permissions</a>
 * <li><a href="#ProcessLifecycle">Process Lifecycle</a>
 * </ol>

Activity 生命周期的7个方法:

 <pre class="prettyprint">
 * public class Activity extends ApplicationContext {
 *     protected void onCreate(Bundle savedInstanceState);
 *     protected void onStart();
 *     protected void onRestart();
 *     protected void onResume();
 *     protected void onPause();
 *     protected void onStop();
 *     protected void onDestroy();
 * }
 * </pre>


onResume() <td>Called when the activity will interacting with the user.  At this point your activity is at the top of the activity stack, with user input going to  <p>Always followed by <code>onPause()</code>.</td>

onResume()的方法调用后,就会放在 activity stack 的栈顶,用户就可以进行交互。

Unless you specify otherwise, a configuration change (such as a change
 * in screen orientation, language, input devices, etc) will cause your
 * current activity to be <em>destroyed</em>, going through the normal activity
 * lifecycle process of {@link #onPause},
 * {@link #onStop}, and {@link #onDestroy} as appropriate.

屏幕方向切换、系统语言、输入设备将会引起当前的 activity 调用 destroyed()。

###代码: 类继承结构

   ↳	android.content.Context   
 	   ↳	android.content.ContextWrapper   
 	 	   ↳	android.view.ContextThemeWrapper   


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