切换到前置摄像头和后置摄像头不起作用

Question

当我在我的代码中调用switchCam方法时，我的应用程序冻结了。那里肯定有问题，但我无法理解是什么问题。有人可以帮我解决我代码中的实际问题。

public class MainActivity extends AppCompatActivity {
private Camera mCamera = null;
SurfaceHolder surfaceHolder=null;
private CameraView mCameraView = null;
int currentCameraId = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);//int flag, int mask

    openCam();
    //setCameraDisplayOrientation(MainActivity.this, currentCameraId, mCamera);

}

public void openCam() {
    try {
        mCamera = Camera.open();//you can use open(int) to use different cameras
    } catch (Exception e) {
        Log.d("ERROR", "Failed to get camera: " + e.getMessage());
        mCamera = Camera.open();//you can use open(int) to use different cameras
    }
    if (mCamera != null) {
        mCameraView = new CameraView(this, mCamera);//create a SurfaceView to show camera data
        FrameLayout camera_view = (FrameLayout) findViewById(R.id.camera_preview);
        camera_view.addView(mCameraView);//add the SurfaceView to the layout
    }

}

public void switchCam(View view){
    int camNum = 0;
    camNum = Camera.getNumberOfCameras();
    int camBackId = Camera.CameraInfo.CAMERA_FACING_BACK;
    int camFrontId = Camera.CameraInfo.CAMERA_FACING_FRONT;
    Toast.makeText(getApplicationContext(),"Hi Cam"+camNum,Toast.LENGTH_SHORT).show();
    Camera.CameraInfo currentCamInfo = new Camera.CameraInfo();

    //if camera is running
    if (mCamera != null){
        //and there is more than one camera
       mCamera.stopPreview();
        mCamera.release();

        //swap the id of the camera to be used
        if(currentCameraId == Camera.CameraInfo.CAMERA_FACING_BACK){
            currentCameraId = Camera.CameraInfo.CAMERA_FACING_FRONT;
        }
        else {
            currentCameraId = Camera.CameraInfo.CAMERA_FACING_BACK;
        }
        mCamera = Camera.open(currentCameraId);

        //setCameraDisplayOrientation(MainActivity.this, currentCameraId, mCamera);
        try {
            mCamera.setPreviewDisplay(surfaceHolder);
        } catch (IOException e) {
            e.printStackTrace();
        }
        mCamera.startPreview();
    }

}

CameraView类在这里

public class CameraView extends SurfaceView implements SurfaceHolder.Callback{
private SurfaceHolder mHolder;
private Camera mCamera;
int currentCameraId=0;
public CameraView(Context context, Camera camera) {
    super(context);
    mCamera = camera;
    //get the holder and set this class as the callback, so we can get camera data here
    mHolder = getHolder();
    mHolder.addCallback(this);
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_NORMAL);
}

@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
    try {
        mCamera.setPreviewDisplay(surfaceHolder);
        mCamera.startPreview();
    }catch (IOException e) {
        Log.d("ERROR", "Camera error on surfaceCreated " + e.getMessage());
    }
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    mCamera.startPreview();

    if(mHolder.getSurface() == null)//check if the surface is ready to receive camera data
        return;
    try{
        mCamera.stopPreview();
    } catch (Exception e){
        //this will happen when you are trying the camera if it's not running
    }
    try{
        mCamera.setPreviewDisplay(mHolder);
        mCamera.startPreview();
    } catch (IOException e) {
        Log.d("ERROR", "Camera error on surfaceChanged " + e.getMessage());
    }
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    mCamera.stopPreview();
    mCamera.release();
}

}

如果您与我分享任何可以帮助我拍摄照片的链接，我将非常高兴。谢谢你提前：）