Launcher启动过程

Android系统启动
SystemServer进程
AMS:ActivityManagerService启动

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时序图

判断TaskDisplayArea

getDefaultTaskDisplayArea()判断

frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java

getHomeIntent() 这就是之前传统的Launcher启动。

shouldPlaceSecondaryHomeOnDisplayArea(taskDisplayArea)判断

ActivityStartController.startHomeActivity()

frameworks/base/services/core/java/com/android/server/wm/ActivityStartController.java

frameworks/base/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java

就是Activity启动流程，最终：

1. mService.startProcessAsync(r, knownToBeDead, isTop, isTop ? "top-activity" : "activity");fork桌面进程
2. realStartActivityLocked(r, wpc, andResume, checkConfig);真正启动Launcher