android 카메라 전환

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
    String TAG = "KTH";
    private SurfaceHolder mHolder;
    private Camera mCamera;
    Activity mCtx;

    public CameraPreview(Context context, Camera camera) {
        super(context);
        mCamera = camera;
        this.mCtx = (Activity) context;

        // SurfaceHolder 가 가지고 있는 하위 Surface가 파괴되거나 업데이트 될경우 받을 콜백을 세팅한다 
        mHolder = getHolder();
        mHolder.addCallback(this);
        // deprecated 되었지만 3.0 이하 버젼에서 필수 메소드라서 호출해둠.
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    }


    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        Logger.log("surfaceCreated done");
        // Surface가 생성되었으니 프리뷰를 어디에 띄울지 지정해준다. (holder 로 받은 SurfaceHolder에 뿌려준다. 
        try {
            Camera.Parameters parameters = mCamera.getParameters();
            if (getResources().getConfiguration().orientation != Configuration.ORIENTATION_LANDSCAPE) {
                Logger.log("camera has open portrait");
                parameters.set("orientation", "portrait");
                mCamera.setDisplayOrientation(90);
                parameters.setRotation(90);
            } else {
                Logger.log("camera has open landscape");
                parameters.set("orientation", "landscape");
                mCamera.setDisplayOrientation(0);
                parameters.setRotation(0);
            }
//            mCamera.setDisplayOrientation(90);
//            parameters.setRotation(90);

            mCamera.setParameters(parameters);
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // 프리뷰 제거시 카메라 사용도 끝났다고 간주하여 리소스를 전부 반환한다
        if (mCamera != null) {
            mCamera.stopPreview();
            mCamera.setPreviewCallback(null);
            mCamera.release();
            mCamera = null;
            Logger.log("카메라 기능 해제");
        }
    }


    private Camera.Size getBestPreviewSize(int width, int height) {
        Logger.log("getBestPreviewSize -> " + width + "," + height);
        Camera.Size result = null;
        Camera.Parameters p = mCamera.getParameters();
//        for (Camera.Size size : p.getSupportedPreviewSizes()) {
//
//            if (size.width <= width && size.height <= height) {
//                if (result == null) {
//                    result = size;
//                } else {
//                    int resultArea = result.width * result.height;
//                    int newArea = size.width * size.height;
//
//                    Logger.log("support camera size -> " + size.width + "," + size.height + "," + resultArea + "," + newArea);
//
//                    if (newArea > resultArea) {
//                        result = size;
//                    }
//                }
//            }
//        }
        return p.getSupportedPreviewSizes().get(0);
//        return result;

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // 프리뷰를 회전시키거나 변경시 처리를 여기서 해준다.
        // 프리뷰 변경시에는 먼저 프리뷰를 멈춘다음 변경해야한다.
        if (mHolder.getSurface() == null) {
            // 프리뷰가 존재하지 않을때
            return;
        }

        // 우선 멈춘다
        try {
            mCamera.stopPreview();
        } catch (Exception e) {
            // 프리뷰가 존재조차 하지 않는 경우다
        }

        // 프리뷰 변경, 처리 등을 여기서 해준다.
        Camera.Parameters parameters = mCamera.getParameters();

        int screen_size[] = CommonUtils.getDisplaySize(mCtx);

        Camera.Size size = getBestPreviewSize( screen_size[0], screen_size[1]);
        parameters.setPreviewSize(size.width, size.height);

        Logger.log("preview size->" + screen_size[1] + "," + screen_size[0] + "," + size.width + "," + size.height);

        mCamera.setParameters(parameters);
        // 새로 변경된 설정으로 프리뷰를 재생성한다
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e) {
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }
}

public class TakeCameraActivity extends AppCompatActivity {

    CameraPreview mPreview;
    Camera mCamera;
    Context mContext;
    FrameLayout preview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_take_camera);
        Userhabit.start(this);

        if(checkCameraHardware(this)) {
            init();
        }

    }

    private boolean checkCameraHardware(Context context) {
        if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA) &&
                context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FRONT)
                ){
            // 카메라가 최소한 한개 있는 경우 처리
            Logger.log("Number of available camera : "+ Camera.getNumberOfCameras());

            return true;
        } else {
            // 카메라가 전혀 없는 경우
            Toast.makeText(this, "No camera found!", Toast.LENGTH_SHORT).show();
            finish();
            return false;
        }
    }


    private void init(){
        mContext = this;

        startCamera(Camera.CameraInfo.CAMERA_FACING_FRONT);

        // 촬영버튼 등록
        Button captureButton = (Button) findViewById(R.id.btnCommonBottom);
        captureButton.setOnClickListener(v -> mCamera.takePicture(null,null,mPicture));

        Button btn = (Button) findViewById(R.id.btn);

       //카메라 전환
        btn.setOnClickListener(v->{ 
            changeCamera();
        });

    }

    boolean isFrontCamera = true;

    private void closeCamera() {
        if(mCamera!=null){
//            mCamera.stopPreview();
//            mCamera.release();
//            mCamera = null;
            mPreview.surfaceDestroyed(mPreview.getHolder());
            mPreview.getHolder().removeCallback(mPreview);
            mPreview.destroyDrawingCache();
            preview.removeView(mPreview);
        }
    }

    public void changeCamera() {
        closeCamera();

        isFrontCamera = !isFrontCamera;
        if (isFrontCamera) {
            startCamera(Camera.CameraInfo.CAMERA_FACING_FRONT);
        } else {
            startCamera(Camera.CameraInfo.CAMERA_FACING_BACK);
        }
//        mCamera.startPreview();
    }

    private void startCamera(int facing){
        mCamera = getCameraInstance(facing);
        mPreview = new CameraPreview(this, mCamera);
        preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview.addView(mPreview);
    }


private Camera getCameraInstance(int facing){
    int cameraCount = 0;
    Camera cam = null;
    Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
    cameraCount = Camera.getNumberOfCameras();
    for (int cameraId = 0; cameraId < cameraCount; cameraId++) {
        Camera.getCameraInfo(cameraId, cameraInfo);
        if (cameraInfo.facing == facing) {
            try {
                cam = Camera.open(cameraId);
                break;
            } catch (RuntimeException e) {
                e.printStackTrace();
            }
        }
    }
    return cam;
}

    private Camera.PictureCallback mPicture = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            // JPEG 이미지가 byte[] 형태로 들어옵니다.
            File pictureFile = getOutputMediaFile();
            if(pictureFile == null){
                Toast.makeText(mContext, "Error camera image saving", Toast.LENGTH_SHORT).show();
                return;
            }

            try{
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
                //Thread.sleep(500);
//                mCamera.startPreview();
                Logger.log("carmera take pickture done");

                Intent intent = new Intent();
                intent.putExtra("taken_camera_image_path" , pictureFile.getAbsolutePath());
                setResult(RESULT_OK , intent);
                finish();

            } catch (FileNotFoundException e) {
                Logger.log("File not found: " + e.getMessage());
            } catch (IOException e) {
                Logger.log("Error accessing file: " + e.getMessage());
            }
        }
    };
}