android - 无法弄清楚为什么总是有值 null

Question

尝试制作一个按钮来捕获图片并将其显示在 imageview 中。我正在临时保存该图像以获得更好的质量。相机不工作，但 imageview 上没有显示任何内容

    private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {

        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {

        }
        if (photoFile != null) {
            Uri photoURI = FileProvider.getUriForFile(this,
                    "com.example.l_sliuzas.fileprovider",
                    photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
        }
    }
}



@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == REQUEST_TAKE_PHOTO && requestCode == RESULT_OK)
    {
        Bitmap bitmapas = BitmapFactory.decodeFile(mCurrentPhotoPath);
        mImageView.setImageBitmap(bitmapas);
    }
}

private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    mCurrentPhotoPath = image.getAbsolutePath();
    return image;
}

Answer 1

这里的REQUEST_TAKE_PHOTO是一个requestCode，RESULT_OK是resultCode。但在 onActivityResult 中，您正在使用 requestCode 评估两者。这是不正确的。

所以下面的代码是不正确的

if (requestCode == REQUEST_TAKE_PHOTO && requestCode == RESULT_OK)
    {
        Bitmap bitmapas = BitmapFactory.decodeFile(mCurrentPhotoPath);
        mImageView.setImageBitmap(bitmapas);
    }

改成

if (requestCode == REQUEST_TAKE_PHOTO && resultCode == RESULT_OK)
    {
        Bitmap bitmapas = BitmapFactory.decodeFile(mCurrentPhotoPath);
        mImageView.setImageBitmap(bitmapas);
    }