使用Zxing库连续扫描二维码，打开相机失败

Question

我正在创建一个二维码扫描应用程序，它可以连续扫描二维码并在同一屏幕上显示结果，而无需关闭相机。

我正在使用 ZXing 库，但是当我触发连续扫描活动时，它无法打开相机。我无法弄清楚这个问题。请检查，我已经在清单中添加了摄像头权限。

代码：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.journeyapps.barcodescanner.DecoratedBarcodeView
        android:id="@+id/barcode_scanner"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_above="@+id/buttonsLayout"
        android:layout_alignParentTop="true">

    </com.journeyapps.barcodescanner.DecoratedBarcodeView>

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:id="@+id/buttonsLayout"
        android:layout_toLeftOf="@+id/centerHorizont">

        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Pause"
            android:onClick="pause" />

        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Resume"
            android:onClick="resume" />
    </LinearLayout>

    <View
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_centerHorizontal="true"
        android:id="@+id/centerHorizont" />

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/centerHorizont"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_alignTop="@id/buttonsLayout"
        android:id="@+id/barcodePreview" />

</RelativeLayout>

Java 代码：

public class ContinuousCaptureActivity extends Activity {
    private static final String TAG = ContinuousCaptureActivity.class.getSimpleName();
    private DecoratedBarcodeView barcodeView;
    private BeepManager beepManager;
    private String lastText;

    private BarcodeCallback callback = new BarcodeCallback() {
        @Override
        public void barcodeResult(BarcodeResult result) {
            if(result.getText() == null || result.getText().equals(lastText)) {
                // Prevent duplicate scans
                return;
            }

            lastText = result.getText();
            barcodeView.setStatusText(result.getText());

            beepManager.playBeepSoundAndVibrate();

            //Added preview of scanned barcode
           ImageView imageView = (ImageView) findViewById(R.id.barcodePreview);
           imageView.setImageBitmap(result.getBitmapWithResultPoints(Color.YELLOW));
        }

        @Override
        public void possibleResultPoints(List<ResultPoint> resultPoints) {
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.continuous_scan);

        barcodeView = (DecoratedBarcodeView) findViewById(R.id.barcode_scanner);
        Collection<BarcodeFormat> formats = Arrays.asList(BarcodeFormat.QR_CODE, BarcodeFormat.CODE_39);
        barcodeView.getBarcodeView().setDecoderFactory(new DefaultDecoderFactory(formats));
        barcodeView.decodeContinuous(callback);

        beepManager = new BeepManager(this);
    }

    @Override
    protected void onResume() {
        super.onResume();

        barcodeView.resume();
    }

    @Override
    protected void onPause() {
        super.onPause();

        barcodeView.pause();
    }

    public void pause(View view) {
        barcodeView.pause();
    }

    public void resume(View view) {
        barcodeView.resume();
    }

    public void triggerScan(View view) {
        barcodeView.decodeSingle(callback);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        return barcodeView.onKeyDown(keyCode, event) || super.onKeyDown(keyCode, event);
    }

这是错误消息，我收到了！

Answer 1

问题是因为权限问题。我已经添加了手动请求权限的代码，现在问题解决了。

感谢@Roberto Manfreda