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android - 条码检测后如何初始化加载器？

问题描述

我有以下问题：

java.lang.IllegalStateException：必须在主线程上调用 initLoader

OnrealizarConsulta方法正是当我调用initLoader.

问题是，在读取条码后，我想查询数据库以了解条码是否已经在其中。但是当我在下面的代码中尝试它抛出IllegalStateException时，我认为将操作移动到EscaneoActivity类中的成员方法将解决问题，但它没有。

public class EscaneoActivity extends AppCompatActivity implements IPostLoaderConsulta {

SurfaceView camara;

private static Barcode codigoActual;


@Override
protected void onCreate(Bundle savedInstanceState) {
    setTitle("Escaner");
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_scaneo);
    camara = (SurfaceView) findViewById(R.id.sv_escaneo_camara);
    configurarCamara();
}

public void realizarConsulta(Bundle b){
    getSupportLoaderManager().initLoader(MainActivity.LOADER_CONSULTOR_PRODUCTOS_DB, //Lanza java.lang.IllegalStateException: initLoader must be called on the main thread
            b,
            AdminSingletons.darInstanciaConsultorProductos(this, EscaneoActivity.this));
}

public void configurarCamara() {
    BarcodeDetector detector = new BarcodeDetector.Builder(this).build();
    final CameraSource cameraSource = new CameraSource.Builder(this, detector)
            .setAutoFocusEnabled(true)
            .setRequestedPreviewSize(1600, 1024)
            .build();

    camara.getHolder().addCallback(new SurfaceHolder.Callback() {
        @Override
        public void surfaceCreated(SurfaceHolder surfaceHolder) {
            if (ActivityCompat.checkSelfPermission(EscaneoActivity.this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                // TODO: Consider calling
                //    ActivityCompat#requestPermissions
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for ActivityCompat#requestPermissions for more details.
                //TODO: Si no tiene los permisos, entonces se deberían solicitar via ActivityCompat.requestPermissions - https://developer.android.com/training/permissions/requesting.html?hl=es-419#perm-request
                return;
            }

            try {
                cameraSource.start(camara.getHolder());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {

        }

        @Override
        public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
            cameraSource.stop();
        }
    });
    detector.setProcessor(new Procesador(this));
}


public class Procesador implements Detector.Processor<Barcode> {

    EscaneoActivity escaneoActivity;

    public Procesador(EscaneoActivity e){
        this.escaneoActivity = e;
    }

    @Override
    public void release() {

    }

    @Override
    public void receiveDetections(Detector.Detections<Barcode> detections) {
        SparseArray<Barcode> objetosDetectados = detections.getDetectedItems();
        if(objetosDetectados.size() > 0) {
            Barcode barcode = objetosDetectados.valueAt(0);
            EscaneoActivity.codigoActual = barcode;
            Bundle b = new Bundle();
            b.putLong(ConsultorProductosBD.X, Long.parseLong(barcode.displayValue));
            escaneoActivity.realizarConsulta(b);
        }
    }

}

标签： androidmultithreadingperformance

解决方案

如果你想在 UI 线程上运行一些东西，你可以使用它：

new Handler(Looper.getMainLooper()).post(new Runnable() {
    @Override
    public void run() {
        // your initloader command
    }
});

但是，如果您使用的是 aLoader它应该在检测到更改时自动查询。所以你做initLoader一次，然后它就会为你完成这项工作。

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