如何使用相机处理片段？

Question

我在主要活动（消息和扫描）中有一个带有2个按钮的应用程序点击扫描打开一个带有摄像头的片段。单击消息将替换扫描片段。直到这里一切都很完美。

然后当我想再次打开相机并点击扫描按钮时 没有反应。没有例外..直到我多次点击..然后相机片段打开。正确打开和关闭片段是否有任何问题？下面是点击和扫描按钮片段代码上的两个按钮的主要活动代码。任何帮助将不胜感激

public void message(View v)
{


    FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    message sms = new message();
    scan scan = new scan();
    if(fragmentManager.findFragmentByTag("scan")!=null) {
       try
       {


           fragmentTransaction.replace(fragmentManager.findFragmentByTag("scan").getId(), sms, "text");
           fragmentTransaction.commit();
           Camera camera = null;
           camera.release();

       }
       catch(Exception exe)
       {
           Toast.makeText(getApplicationContext(), exe.getMessage(),Toast.LENGTH_SHORT);
       }

    }


}



    public void scan(View v)
    {
        FragmentManager fragmentManager = getFragmentManager();
       FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();


        scan scan = new scan();
        if(fragmentManager.findFragmentByTag("text")!=null) {



            try
            {
                fragmentTransaction.replace(fragmentManager.findFragmentByTag("text").getId(), scan, "scan");
                fragmentTransaction.commit();
            }
            catch(Exception exe)
            {
                Toast.makeText(getApplicationContext(), exe.getMessage(),Toast.LENGTH_SHORT);
            }


        }


    }

扫描按钮打开一个片段，这是该片段的java类

private OnFragmentInteractionListener mListener;

    public scan() {
    }
    @Override
    public void handleResult(Result rawResult) {
       

        Log.e("handler", rawResult.getText()); 
        Log.e("handler", rawResult.getBarcodeFormat().toString()); 

        
        AlertDialog.Builder builder = new AlertDialog.Builder(this.getActivity());
        builder.setTitle("Scan Result");
        builder.setMessage(rawResult.getText());
        number = rawResult.getText().substring(rawResult.getText().length() - 13);

        final EditText input = new EditText(this.getActivity());

        input.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
        builder.setView(input);


        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                m_Text = input.getText().toString();

               
            }
        });
        builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();
            }
        });

        builder.setNegativeButton("NO",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.cancel();
                    }
                });

        AlertDialog alert1 = builder.create();
        alert1.show();

        zXingScannerView.resumeCameraPreview(this);
    }

    public static scan newInstance(String param1, String param2) {
        scan fragment = new scan();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }

        if(checkCameraHardware(getActivity().getApplicationContext())) {
            zXingScannerView = new ZXingScannerView(this.getActivity().getApplicationContext());
            zXingScannerView.setResultHandler(this);
            zXingScannerView.startCamera();
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_scan, container, false);


        FrameLayout preview =(FrameLayout)view.findViewById(R.id.camera_preview);
        preview.addView(zXingScannerView);
       return view;
    }
@Override
public   void onPause()
{
    super.onPause();
zXingScannerView.stopCamera();
}
    @Override
    public void onResume() {
        super.onResume();
        zXingScannerView.setResultHandler(this); // Register ourselves as a handler for scan results.
        zXingScannerView.startCamera();          // Start camera on resume
    }

    /** Check if this device has a camera */
    public boolean checkCameraHardware(Context context) {
        if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
            // this device has a camera
            return true;
        } else {
            // no camera on this device
            return false;
        }
    }


    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {

        if (mCamera!= null) {
            mCamera.stopPreview();
           mCamera.release();
            mCamera = null;
        }
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }
}