When a service is unbound from all clients, the Android system destroys it (unless it was also started with onStartCommand()). As such, you don't have to manage the lifecycle of your service if it's purely a bound service—the Android system manages it for you based on whether it is bound to any clients.
boundservice不需要你操行他的生命周期
However, if you choose to implement the onStartCommand() callback method, then you must explicitly stop the service, because the service is now considered to be started. In this case, the service runs until the service stops itself with stopSelf() or another component calls stopService(), regardless of whether it is bound to any clients.
然而，如果是startService要注意手动关掉
Additionally, if your service is started and accepts binding, then when the system calls your onUnbind() method, you can optionally return true if you would like to receive a call to onRebind() the next time a client binds to the service. onRebind() returns void, but the client still receives the IBinder in its onServiceConnected() callback. The following figure illustrates the logic for this kind of lifecycle.
翻译：startService如果在onUnbind时候返回true ,看源码解释。
* @return Return true if you would like to have the service's * {@link #onRebind} method later called when new clients bind to it. */ public boolean onUnbind(Intent intent) { return false; }Figure 1. The lifecycle for a service that is started and also allows binding.
参考：For more information about the lifecycle of a started service, see the Services document.
