Activity : Activity is the Android applications interact with the user's window, Android is one of the most basic building blocks it needs to maintain the status of each interface, a lot of persistence to do things properly manage the life cycle and some jump logic
-Service : background service in Activity, encapsulated with a fully functional logic implementations, the upper receiving instruction, to complete the relevant food, well defined need to provide an excuse acceptable Intent synchronous and asynchronous ; q% w + U
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Content Provider : a third-party application data access solutions provided by Android, you can derive Content Provider classes provide external data, you can choose to sort like databases, shielding the details of the internal data storage, providing a unified model of outward excuse , greatly simplifying the upper application of data integration provides a more convenient way to # q + t T $] *
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BroadCast Receiver : receiving one or more of Intent for a triggering event, accept the message, do some simple processing, converted into a Notification, unified event broadcast model of Android : ~
Reproduced in: https: //my.oschina.net/tiwer/blog/199858