source code :https://github.com/fantasyRqg/MytestApp/tree/AndroidLaunchModeTest
以下文字摘自
主要解释关于 FLAG_ACTIVITY_NEW_TASK 和 singleTask 的特性
When the intent that launches an activity contains the FLAG_ACTIVITY_NEW_TASK flag.
A new activity is, by default, launched into the task of the activity that called startActivity(). It's pushed onto the same back stack as the caller. However, if the intent passed to startActivity() contains theFLAG_ACTIVITY_NEW_TASK flag, the system looks for a different task to house the new activity. Often, it's a new task. However, it doesn't have to be. If there's already an existing task with the same affinity as the new activity, the activity is launched into that task. If not, it begins a new task.