要实现不关闭zxing相机，可以使用以下代码示例：

import android.content.Context;
import android.hardware.Camera;
import android.os.Handler;
import android.os.Looper;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.PlanarYUVLuminanceSource;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.common.GlobalHistogramBinarizer;

import java.io.IOException;
import java.util.Map;


public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback, Camera.PreviewCallback {

    private static final String TAG = "CameraPreview";

    private Context mContext;
    private SurfaceHolder mHolder;
    private Camera mCamera;
    private Handler mHandler;
    private DecodeCallback mDecodeCallback;

    public CameraPreview(Context context, DecodeCallback decodeCallback) {
        super(context);
        mContext = context;
        mDecodeCallback = decodeCallback;

        mHolder = getHolder();
        mHolder.addCallback(this);
    }

    public void surfaceCreated(SurfaceHolder holder) {
        try {
            mCamera = Camera.open();
            mCamera.setPreviewDisplay(holder);
            mCamera.setDisplayOrientation(90);

            mHandler = new Handler(Looper.getMainLooper());
            mCamera.setPreviewCallback(this);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        releaseCamera();
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        if (mHolder.getSurface() == null) {
            return;
        }

        try {
            mCamera.stopPreview();
        } catch (Exception e) {
            // ignore: tried to stop a non-existent preview
        }

        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.setDisplayOrientation(90);

            mHandler = new Handler(Looper.getMainLooper());
            mCamera.setPreviewCallback(this);
            mCamera.startPreview();
        } catch (Exception e) {
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }

    public void releaseCamera() {
        if (mCamera != null) {
            try {
                mCamera.setPreviewCallback(null);
                mCamera.stopPreview();
                mCamera.release();
                mCamera = null;
            } catch (Exception e) {
                Log.e(TAG, "Error releasing camera: " + e.getMessage());
            }
        }
    }

    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        mHandler.post(new Runnable() {
            @Override
            public void run() {
                if (mCamera != null) {
                    Camera.Parameters parameters = mCamera.getParameters();
                    int imageFormat = parameters.getPreviewFormat();
                    int width = parameters.getPreviewSize().width;
                    int height = parameters.getPreviewSize().height;

                    PlanarYUVLuminanceSource source = new PlanarYUVLuminanceSource(data, width, height, 0, 0, width, height, false);
                    BinaryBitmap bitmap = new BinaryBitmap(new GlobalHistogramBinarizer(source));

                    MultiFormatReader reader = new MultiFormatReader();
                    Map hints = new Hashtable<>();
                    hints.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);
                    hints.put(DecodeHintType.POSSIBLE_FORMATS, DecodeFormat.ALL_FORMATS);
                    reader.setHints(hints);

                    try {
                        Result result = reader.decode(bitmap);
                        mDecodeCallback.onDecodeSuccess(result);
                    } catch (ReaderException e) {
                        // QR code not found, do nothing
                    } finally {
                        mCamera.setPreviewCallback(CameraPreview.this);
                    }
                }
            }
        });
    }

    public interface DecodeCallback {
        void onDecodeSuccess(Result result);
    }
}

上面的代码是一个自定义的CameraPreview类，继承自SurfaceView，并实现了SurfaceHolder.Callback和Camera.PreviewCallback接口。在surfaceCreated方法中打开相机并设置预览，同时设置PreviewCallback用于获取预览帧数据。在surfaceDestroyed方法中释放相机资源。在onPreviewFrame方法中进行解码操作，并通过DecodeCallback将解码结果返回。

使用时可以在Activity中添加以下代码：

public class MainActivity extends AppCompatActivity implements CameraPreview.DecodeCallback {

    private static final String TAG = "MainActivity";

    private CameraPreview mCameraPreview;
    private TextView mResultTextView;

    @Override