Android系统横竖屏切换时候Activity的生命周期
16lz
2021-01-25
网上看到有文章说横屏切换成竖屏的时候会打印两次相同的Log，百思不得其解啊，于是自己动手验证一下。
环境：
AndroidStudio 2.1.2
minSdkVersion 15 、targetSdkVersion 23
设备：Genymotion 4.1.1-API16
分为两个步骤：
- 不添加android:configChanges属性
- 添加android:configChanges=”orientation|screenSize”
源代码
MainActivity.class
package com.example.activitydemo;import android.app.Activity;import android.content.res.Configuration;import android.os.Bundle;import android.util.Log;public class MainActivity extends Activity { private String TAG = "MainActivity"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Log.i(TAG, "onCreate: "); } @Override protected void onStart() { super.onStart(); Log.i(TAG, "onStart: "); } @Override protected void onResume() { super.onResume(); Log.i(TAG, "onResume: "); } @Override protected void onPause() { super.onPause(); Log.i(TAG, "onPause: "); } @Override protected void onStop() { super.onStop(); Log.i(TAG, "onStop: "); } @Override protected void onDestroy() { super.onDestroy(); Log.i(TAG, "onDestroy: "); } @Override protected void onRestart() { super.onRestart(); Log.i(TAG, "onRestart: "); } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); Log.i(TAG, "onSaveInstanceState: "); } @Override protected void onRestoreInstanceState(Bundle savedInstanceState) { super.onRestoreInstanceState(savedInstanceState); Log.i(TAG, "onRestoreInstanceState: "); } @Override public void onConfigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); Log.i(TAG, "onConfigurationChanged: "); }}AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>"http://schemas.android.com/apk/res/android" package="com.example.activitydemo"> "true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/AppTheme"> ".MainActivity"> "android.intent.action.MAIN" /> "android.intent.category.LAUNCHER" /> 1.不添加android:configChanges属性:
-
- 创建Activity：
- MainActivity: onCreate:
- MainActivity: onStart:
- MainActivity: onResume:
-
- 旋转至横屏：
- MainActivity: onPause:
- MainActivity: onSaveInstanceState:
- MainActivity: onStop:
- MainActivity: onDestroy:
- MainActivity: onCreate:
- MainActivity: onStart:
- MainActivity: onRestoreInstanceState:
- MainActivity: onResume:
-
- 旋转至竖屏：
- MainActivity: onPause:
- MainActivity: onSaveInstanceState:
- MainActivity: onStop:
- MainActivity: onDestroy:
- MainActivity: onCreate:
- MainActivity: onStart:
- MainActivity: onRestoreInstanceState:
- MainActivity: onResume:
-
- 再旋转至横屏：
- MainActivity: onPause:
- MainActivity: onSaveInstanceState:
- MainActivity: onStop:
- MainActivity: onDestroy:
- MainActivity: onCreate:
- MainActivity: onStart:
- MainActivity: onRestoreInstanceState:
- MainActivity: onResume:
小结：横竖屏切换Activity的生命周期跟预想的一样，只重启了一次。可以理解为先销毁竖屏的Activity，再创建横屏的Activity。网上说的打印两次Log的说法不知道是怎么来的。
2.添加android:configChanges属性:orientation|screenSize
".MainActivity" android:configChanges="orientation|screenSize"> "android.intent.action.MAIN" /> "android.intent.category.LAUNCHER" /> ps: 若编译选项中的minSdkVersion和targetSdkVersion有一项大于13时，需同时添加orientation|screenSize属性才能防止旋转屏幕时Activity重启
-
- 创建Activity：
- MainActivity: onCreate:
- MainActivity: onStart:
- MainActivity: onResume:
-
- 旋转至横屏：
- MainActivity: onConfigurationChanged:
-
- 旋转至竖屏：
- MainActivity: onConfigurationChanged:
小结：可以看到，添加了android:configChanges=”orientation|screenSize”属性的Activity在旋转屏幕时不会重启。
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