public class MainActivity extends Activity {  
  
  @Override  
  protected void onCreate(Bundle savedInstanceState) {  
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.activity_main);  
  }  
  
  public void startService(View source) {  
    // 创建所需要启动的Service的Intent  
    Intent intent = new Intent(this, MyService.class);  
    startService(intent);  
  }  
  
  public void startIntentService(View source) {  
    // 创建需要启动的IntentService的Intent  
    Intent intent = new Intent(this, MyIntentService.class);  
    startService(intent);  
  }  
}  

public class MyIntentService extends IntentService {  
  
  public MyIntentService() {  
    super("MyIntentService");  
  }  
  
  @Override  
  protected void onHandleIntent(Intent intent) {  
    // IntentService会使用单独的线程来执行该方法的代码  
    // 该方法内执行耗时任务，比如下载文件，此处只是让线程等待20秒  
    long endTime = System.currentTimeMillis() + 20 * 1000;  
    System.out.println("onStart");  
    while (System.currentTimeMillis() < endTime) {  
      synchronized (this) {  
        try {  
          wait(endTime - System.currentTimeMillis());  
        } catch (InterruptedException e) {  
          e.printStackTrace();  
        }  
      }  
    }  
    System.out.println("----耗时任务执行完成---");  
  }  
}  
 

public class MyService extends Service {  
  
  @Override  
  public IBinder onBind(Intent arg0) {  
    return null;  
  }  
  
  @Override  
  public int onStartCommand(Intent intent, int flags, int startId) {  
    // 该方法内执行耗时任务可能导致ANR(Application Not Responding)异常  
    long endTime = System.currentTimeMillis() + 20 * 1000;  
    System.out.println("onStart");  
    while (System.currentTimeMillis() < endTime) {  
      synchronized (this) {  
        try {  
          wait(endTime - System.currentTimeMillis());  
        } catch (InterruptedException e) {  
          e.printStackTrace();  
        }  
      }  
    }  
    System.out.println("----耗时任务执行完成---");  
    return START_STICKY;  
  }  
}