Android关于Launcher的Activity启动两次的问题调查

最新推荐文章于 2024-08-13 15:07:07 发布

原创最新推荐文章于 2024-08-13 15:07:07 发布 · 3.2k 阅读

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文章标签：

#Launcher #Activity #启动两次 #configchanges #config

本文探讨了Launcher在设备开机时启动两次的问题，分析了安卓机制下Configuration变化导致的Activity重启现象，并提供了通过修改AndroidManifest.xml文件中Activity的configChanges属性来避免重复启动的方法。

在开机的时候，发现launcher的Activity启动了两次。

经过开机打印Log发现：
2019-08-05 16:37:31.891 1754-1800/system_process W/WindowManager: Force clearing freeze: AppWindowToken{f258030 token=Token{59f4973 ActivityRecord{ad731e2 u0 com.ad.launcher/.LauncherActivity t25}}}

发现Launcher被停止掉了，然后重新启动。

经过调查发现，安卓机制，当Configuration配置发生变化是，Launcher会重新启动。详细参考官网说明：
https://developer.android.com/reference/android/content/res/Configuration
https://developer.android.com/guide/topics/manifest/activity-element

根据文档：
在这里插入图片描述
所以，只要AndroidManifest.xml中的Activity增加属性android:configChanges就可以保持Activity运行，不用重新启动Activity。

那么我的项目中到底哪个Configuration发生了变化呢？

继续查看卡机打印Log，发现：
2019-08-05 16:37:28.043 1754-1848/system_process I/ActivityManager: Config changes=8 {1.0 ?mcc?mnc [en_US] ldltr sw811dp w1442dp h675dp 213dpi lrg long land car night finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 0, 0) mAppBounds=Rect(0, 0 - 1920, 931) mWindowingMode=fullscreen mActivityType=undefined} s.7}
2019-08-05 16:37:28.100 1754-1848/system_process I/ActivityManager: Override config changes=8 {1.0 ?mcc?mnc [en_US] ldltr sw811dp w1442dp h675dp 213dpi lrg long land car night finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1920, 931) mAppBounds=Rect(0, 0 - 1920, 931) mWindowingMode=fullscreen mActivityType=undefined} s.7} for displayId=0

Config changes=8，根据官方文档和代码：
在这里插入图片描述

    /**
     * Bit in {@link #configChanges} that indicates that the activity
     * can itself handle changes to the touchscreen type.  Set from the
     * {@link android.R.attr#configChanges} attribute.
     */
    public static final int CONFIG_TOUCHSCREEN = 0x0008;

发现发生变化的属性是CONFIG_TOUCHSCREEN，所以在Activity属性中增加：
android:configChanges=“screenSize”

监听变化来知道哪个CONFIG发生了变化：

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);

        // Checks the orientation of the screen
        if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
            Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
        } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT){
            Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
        }

        Log.i(TAG,"config" + newConfig);
        Log.i(TAG,"config.fontScale" + newConfig.fontScale);
        Log.i(TAG,"config.colorMode" + newConfig.colorMode);
        Log.i(TAG,"config.densityDpi" + newConfig.densityDpi);
        Log.i(TAG,"config.hardKeyboardHidden" + newConfig.hardKeyboardHidden);
        Log.i(TAG,"config.keyboard" + newConfig.keyboard);
        Log.i(TAG,"config.keyboardHidden" + newConfig.keyboardHidden);
        Log.i(TAG,"config.mcc" + newConfig.mcc);
        Log.i(TAG,"config.mnc" + newConfig.mnc);
        Log.i(TAG,"config.navigation" + newConfig.navigation);
        Log.i(TAG,"config.navigationHidden" + newConfig.navigationHidden);
        Log.i(TAG,"config.orientation" + newConfig.orientation);
        Log.i(TAG,"config.screenHeightDp" + newConfig.screenHeightDp);
        Log.i(TAG,"config.screenLayout" + newConfig.screenLayout);
        Log.i(TAG,"config.uiMode" + newConfig.uiMode);
        Log.i(TAG,"config.touchscreen" + newConfig.touchscreen);
        Log.i(TAG,"config.smallestScreenWidthDp" + newConfig.smallestScreenWidthDp);
        Log.i(TAG,"config.smallestScreenWidthDp" + newConfig.touchscreen);
    }