android 10 替换默认Launcher或开机引导app后，可能会引起首次开机黑屏（FallbackHome界面）一段时间，才会加载显示界面_android fallbackhome

最近公司新项目是基于android 10的产品，需要更换一些原生的app，发现首次刷机后开机动画播完会进入一个黑屏界面，过10s左右才会进入开机引导界面，就抓log分析发现当前是FallbackHome，可看dumpsys 信息，如下

$ adb shell dumpsys activity activities | grep Resume
          state=RESUMED stopped=false delayedResume=false finishing=false
    mResumedActivity: ActivityRecord{9bcec35 u0 com.android.settings/.FallbackHome t2}
 ResumedActivity:ActivityRecord{9bcec35 u0 com.android.settings/.FallbackHome t2}
  ResumedActivity: ActivityRecord{9bcec35 u0 com.android.settings/.FallbackHome t2}

然后就了解FallbackHome，关于FallbackHome大家可自行百度或google了解。

现在问题来了，如何解决黑屏问题？

解决方案：延长开机动画，当FallbackHome消失时结束开机动画。

修改方案：

1.找到 frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java

private void performEnableScreen()函数：

............

if (!mBootAnimationStopped) {
Trace.asyncTraceBegin(TRACE_TAG_WINDOW_MANAGER, "Stop bootanim", 0);

// stop boot animation

// formerly we would just kill the process, but we now ask it to exit so it

// can choose where to stop the animation.

//start  屏蔽系统结束开机动画的代码

//SystemProperties.set("service.bootanim.exit", "1");

//end

mBootAnimationStopped = true;

}
2.重新设置系统结束开机动画的代码

frameworks/base/services/core/java/com/android/server/am/ActivityRecord.java

找到ActivityRecord构造函数，如下：

ActivityRecord(ActivityTaskManagerService _service, WindowProcessController _caller,

.............

//start 添加代码，结束开机广播
if (isHomeIntent(intent) && shortComponentName != null && shortComponentName.contains("FallbackHome")) {
    SystemProperties.set("service.bootanim.exit", "1");
    Log.d(TAG, "real home....." + shortComponentName);
}

3.frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

搜索service.bootanim.exit

注释调这行

//property_set("service.bootanim.exit", "1");