onDetach ,onAttach,onPostExecute,RetianFragment方法周期，解释的不错

It is not possible for 

onPostExecute()

 to
be called in between 

Fragment#onDetach()

 and 

Fragment#onAttach()

 during
a configuration change. The reasoning behind this claim is threefold:

Configuration changes are handled inside a single message in the main thread's message queue.

As soon as the 

doInBackground()

 method
returns, the 

AsyncTask

 schedules
the 

onPostExecute()

 method
to be invoked on the main thread by posting a message to the main thread's message queue.

The configuration change's message will contain the code that will invoke the 

Activity

 and 

Fragment

 lifecycle
methods (such as 

onDetach()

 and 

onAttach()

).
The 

AsyncTask

's
message will contain the code that will invoke the 

onPostExecute()

 method.
Since the main thread processes messages in its message queue sequentially, it is impossible for the two messages to be executed at the same time, and therefore 

onPostExecute()

 can
never be invoked in between the calls to 

onDetach()

 and 

onAttach()

.