android中service与线程

android sdk中的描述

Caution: A service runs in the main thread of its hosting process—the service does not create its own thread and does not run in a separate process (unless you specify otherwise). This means that, if your service is going to do any CPU intensive work or blocking operations (such as MP3 playback or networking), you should create a new thread within the service to do that work. By using a separate thread, you will reduce the risk of Application Not Responding (ANR) errors and the application's main thread can remain dedicated to user interaction with your activities.

service是运行在主线程上的，而不是运行在另一个线程中，如果你想在service中处理很占时间的操作，你必须在service中开线程，这样可以降低activity没有响应的风险。

Should you use a service or a thread?

A service is simply a component that can run in the background even when the user is not interacting with your application. Thus, you should create a service only if that is what you need.

If you need to perform work outside your main thread, but only while the user is interacting with your application, then you should probably instead create a new thread and not a service. For example, if you want to play some music, but only while your activity is running, you might create a thread inonCreate(), start running it in onStart(), then stop it in onStop(). Also consider using AsyncTask orHandlerThread, instead of the traditional Threadclass. See the Processes and Threading document for more information about threads.

Remember that if you do use a service, it still runs in your application's main thread by default, so you should still create a new thread within the service if it performs intensive or blocking operations.

  服务可以在后台运行即使当用户没有激活界面。