【Android(安卓)开发教程】在服务中执行耗时操作

本章节翻译自《Beginning-Android-4-Application-Development》，如有翻译不当的地方，敬请指出。

原书购买地址http://www.amazon.com/Beginning-Android-4-Application-Development/dp/1118199545/

上一节创建的服务实际上并没有做任何有用的事情，这一节将修改一下它，让它去执行一个任务：模拟下载文件。

1. 使用上一节的Services工程，做一点修改。

public class MyService extends Service {    @Override    public IBinder onBind(Intent arg0) {        return null;    }@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {// We want this service to continue running until it is explicitly// stopped, so return sticky.// Toast.makeText(this, "Service Started", Toast.LENGTH_LONG).show();        try {int result = DownloadFile(new URL("http://www.abcd.com/file.zip"));Toast.makeText(getBaseContext(),"Downloaded " + result + " bytes",Toast.LENGTH_LONG).show();        } catch (MalformedURLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }return START_STICKY;}    private int DownloadFile(URL url) {        try {            //---simulate taking some time to download a file---            Thread.sleep(5000);        } catch (InterruptedException e) {             e.printStackTrace();        }        //---return an arbitrary number representing         // the size of the file downloaded---        return 100;    }        @Overridepublic void onDestroy() {super.onDestroy();Toast.makeText(this, "Service Destroyed", Toast.LENGTH_LONG).show();}}

2. 在模拟器上面进行调试。点击start按钮，开始下载文件。

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