Question

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丢弃接收器一旦被解雇的正常行为，因为，我正在寻找更永久的东西，我正在尝试使用服务来维持广播接收器活动，但是我遇到了一些我无法理解的错误。

那么以什么方式可以在服务中使用广播接收器？

我正在放置一个错误日志，以及我的部分代码。

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)

主要类

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);
    }
}

服务类

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！

Answer 1

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

在Tools

的onCreate中创建Servicio个实例

private Tools NetWork = null;

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

然后在您的Tools类中将此传入的Context存储在私有变量（例如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();
}

修改

要了解Context，您可以参考以下参考资料

demystifyind context

Context, What Context

如何管理服务中的广播接收器

1 个答案: