@Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {
            Toast.makeText(getActivity(),"需要授予必要的权限才能继续运行",Toast.LENGTH_LONG).show();
            ActivityCompat.requestPermissions(this.getActivity(), PERMISSIONS, REQUEST_CODE_PERMISSIONS);
@Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (allPermissionsGranted()) {
            startCamera(getContext());
        } else {
            Toast.makeText(getActivity(),"需要授予必要的权限才能继续运行",Toast.LENGTH_LONG).show();
            ActivityCompat.requestPermissions(getActivity(), PERMISSIONS, REQUEST_CODE_PERMISSIONS);
在Fragment中使用ActivityCompat.requestPermissions,只会去调用宿主Activity的onRequestPermissionsResult,而没有调用Fragment的该方法。

解决(正确的权限申请姿势):
使用requestPermissions方法即可,该方法是Fragment的类方法,这个方法才会去回调Fragment的onRequestPermissionsResult

修改后代码

@Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {
            Toast.makeText(getActivity(),"需要授予必要的权限才能继续运行",Toast.LENGTH_LONG).show();
            requestPermissions(PERMISSIONS, REQUEST_CODE_PERMISSIONS);
@Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (allPermissionsGranted()) {
            startCamera(getContext());
        } else {
            Toast.makeText(getActivity(),"需要授予必要的权限才能继续运行",Toast.LENGTH_LONG).show();
            requestPermissions(PERMISSIONS, REQUEST_CODE_PERMISSIONS);