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我正在编写一个应用程序，其主要目标是在我的设备连接到 AC 时启动 TuneIn 播放器。第一个版本只使用广播接收器，它运行良好，除了 android OS 丢弃接收器一旦触发的正常行为，因为，我正在寻找更永久的东西我正在尝试使用服务来保持广播接收器处于活动状态，但我遇到了一些我无法理解的错误。

那么以何种方式可以在服务中使用广播接收器呢？

我正在输入一个错误日志和我的代码的一部分。

错误：

07-19 08:03:27.019: ERROR/AndroidRuntime(15785): FATAL EXCEPTION: main
        java.lang.RuntimeException: Error receiving broadcast Intent { act=android.intent.action.BATTERY_CHANGED flg=0x60000000 (has extras) } in com.upm.radioC.Servicio$1@407a0420
        at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:722)
        at android.os.Handler.handleCallback(Handler.java:587)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:130)
        at android.app.ActivityThread.main(ActivityThread.java:3683)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:507)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:895)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:653)
        at dalvik.system.NativeStart.main(Native Method)
        Caused by: java.lang.IllegalStateException: System services not available to Activities before onCreate()
        at android.app.Activity.getSystemService(Activity.java:3536)
        at com.upm.radioC.Tools.checkData(Tools.java:26)
        at com.upm.radioC.Servicio$1.onReceive(Servicio.java:60)
        at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:709)

主班 

public class Inicio extends Activity {
  @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);}

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflador = getMenuInflater();
        inflador.inflate(R.menu.menu, menu);
        return true;
    }

    @Override
    public boolean onMenuItemSelected(int featureId, MenuItem opcion) {
        TextView btn = (TextView) findViewById(R.id.txtEtiqueta);
        Intent svc = new Intent(this, Servicio.class);
        switch (opcion.getItemId()) {
            case R.id.mnuRegistra:
                startService(svc);
                btn.setText("Monitoreo Iniciado");
                break;
            case R.id.mnuLibera:
                stopService(svc);
                btn.setText("Monitoreo Detenido");
                break;
        }
        return super.onMenuItemSelected(featureId, opcion);
    }
}

服务等级 

public class Servicio extends Service {

    private BroadcastReceiver receiver;
    private IntentFilter filter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
    private Tools NetWork = new Tools(); //Custom Class for activate/deactivate GSM data

    @Override
    public IBinder onBind(Intent arg0) {
        return null;}

    @Override
    public void onCreate() {
        super.onCreate();}

    @Override
    public int onStartCommand(Intent i, int flags, int startID) {
        _startService();
        return START_STICKY; }

    @Override
    public void onDestroy() {
        super.onDestroy();
        _shutdownService(); }

    private void _startService() {
        receiver = new BroadcastReceiver() {
            public void onReceive(Context context, Intent intent) {
                int plugged = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
                if (plugged == BatteryManager.BATTERY_PLUGGED_USB) {
                    Toast.makeText(getApplicationContext(), "Conectado a USB", Toast.LENGTH_LONG).show();                    
                }else if (plugged == BatteryManager.BATTERY_PLUGGED_AC) {
                    if (!NetWork.checkData()) try {
                        NetWork.turnData(true);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    Intent LaunchIntent = getPackageManager().getLaunchIntentForPackage("tunein.player");
                    startActivity(LaunchIntent);
                    Toast.makeText(getApplicationContext(), "Conectado a AC", Toast.LENGTH_LONG).show();
                } else {
                    if (NetWork.checkData()) try {
                        NetWork.turnData(false);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    Toast.makeText(getApplicationContext(), "Desconectado de las fuentes de poder", Toast.LENGTH_LONG).show();
                }
            }
        };
        registerReceiver(receiver, filter);
    }

    private void _shutdownService() {
        unregisterReceiver(receiver);}

}

提前致谢！

4

1 回答 1

1

看起来它与您调用的上下文有关getSystemService。尝试将服务上下文传递给Tools类，然后使用该上下文调用getSystemService.

创建Tools实例onCreate_Servicio

private Tools NetWork = null;

@Override
public void onCreate() {
    super.onCreate();
    Network = new Tools(this);
}

然后在你的Tools类中将这个传入存储Context在一个私有变量（比如mContext）中，并在该类的方法中使用它。

boolean checkData() { 
    ConnectivityManager connManager = (ConnectivityManager) mContext.getSystemService(CONNECTIVITY_SERVICE); 
    NetworkInfo mMobile = connManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
    return mMobile.isConnected();
}

编辑：

为了理解上下文，您可以参考以下参考资料

  1. 揭秘语境

  2. 上下文，什么上下文

于 2013-07-20T22:44:26.863 回答