Question

这是QR Code扫描仪应用程序的一部分。在应用程序的最开始，它要求获得摄像头许可，当我单击以允许时，应用程序没有响应。但从第二次开始，该应用即可正常运行。我认为错误可能在于检查权限。请帮助我找到错误。

surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
        @Override
        public void surfaceCreated(SurfaceHolder holder) {
            try {
                if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {

                    cameraSource.start(surfaceView.getHolder());
                } else {
                    ActivityCompat.requestPermissions(MainActivity.this, new
                            String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
                }

            } catch (IOException e) {
                e.printStackTrace();
            }

        }

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

        @Override
        public void surfaceDestroyed(SurfaceHolder holder) {
            cameraSource.stop();
        }
    });

Answer 1

在授予/拒绝您的许可后，将有一个名为onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults)的回调方法。

回调函数返回requestCode，这是首先被调用的代码权限。

您需要检查的所有内容

requestCode等于您要求的许可权
grandResult[]数组不为空
grantResults[0]等于PackageManager.PERMISSION_GRANTED

示例：

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {

    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST: { // here, MY_PERMISSIONS_REQUEST is the intended request code
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                // permission was granted, yay! Do the task you need to do.

            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
}

应用未响应相机许可

1 个答案: