android IPC: AIDL thread is not blocked.
AIDL线程是不被阻塞的
Using AIDL is necessary only if you allow clients from different applications to access your service for IPC and want to handle multithreading in your service.
使用AIDL是必要的（你允许来自不同应用程序的客户端访问你的服务的通过IPC机制，而且在你的服务端想去处理多线程）
If you do not need to perform concurrent IPC across different applications, you should create your interface by implementing a Binder or, if you want to perform IPC, but do not need to handle multithreading, implement your interface using a Messenger. Regardless, be sure that you understand Bound Services before implementing an AIDL.
When used, a remote call does not block; it simply sends the transaction data and immediately returns.
