Question

在我的应用中，我让用户有机会获得照片并将其设置为个人资料照片。有两种方法可以从图库中获取照片，也可以直接使用相机拍摄照片。

我编写的代码与booth方法一起使用，我已经在使用棒棒糖5.0的Galaxy S5上进行了测试。使用KitKat 4.4.4进行测试时，它会抛出一个NPE。但是直接从相机拍摄照片时就会抛出这个NPE。

在展位案例中，这是我遵循的结构：

从onActivityResult呼叫数据中获取Uri。
获取pic方向值（在某些情况下，纵向图像在imageview中显示为旋转）。
对位图进行解码以缩小它的纵横比。
如果图像方向错误，请旋转图像。
将位图保存在内部应用数据中。

这是“从相机拍照”请求的代码：

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {
        case TAKE_PHOTO_REQUEST_FRAG:
            if (resultCode == getActivity().RESULT_OK && data != null) {

                Uri selectedImageUri = data.getData();
                Bitmap srcBmp = null;

                /*Get image orientation*/
                int orientation = getImageOrientation(getActivity(), selectedImageUri);
                Log.d("IMAGE_ORIENTATION", String.valueOf(orientation));

                /*Downsize bitmap mantaining aspect ratio*/
                srcBmp = decodeSampledBitmapFromUri(
                        selectedImageUri,
                        pic_view.getWidth(), pic_view.getHeight());

                /*Rotate image if needed*/
                if (orientation == 90) {
                    Matrix matrix = new Matrix();
                    matrix.postRotate(90);
                    srcBmp = Bitmap.createBitmap(srcBmp, 0, 0,
                            srcBmp.getWidth(), srcBmp.getHeight(), matrix,
                            true);
                }
                else if (orientation == 180) {
                    Matrix matrix = new Matrix();
                    matrix.postRotate(180);
                    srcBmp = Bitmap.createBitmap(srcBmp, 0, 0,
                            srcBmp.getWidth(), srcBmp.getHeight(), matrix,
                            true);
                }
                else if (orientation == 270) {
                    Matrix matrix = new Matrix();
                    matrix.postRotate(270);
                    srcBmp = Bitmap.createBitmap(srcBmp, 0, 0,
                            srcBmp.getWidth(), srcBmp.getHeight(), matrix,
                            true);
                }

                /*Save bitmap in internal memory*/
                ContextWrapper cw1 = new ContextWrapper(getActivity().getApplicationContext());
                File directory1 = cw1.getDir("profile", Context.MODE_PRIVATE);
                if (!directory1.exists()) {
                    directory1.mkdir();
                }
                File filepath1 = new File(directory1, "profile_pic.png");
                FileOutputStream fos1 = null;
                try {
                    fos1 = new FileOutputStream(filepath1);
                    srcBmp.compress(Bitmap.CompressFormat.JPEG, 90, fos1);
                    fos1.close();
                } catch (Exception e) {
                    Log.e("SAVE_FULL_IMAGE", e.getMessage(), e);
                }

                /*Show image in imageview*/
                pic_view.setImageBitmap(srcBmp);
            }
            break;
    }
}

-

/*Downsize the bitmap from uri*/
public Bitmap decodeSampledBitmapFromUri(Uri uri, int reqWidth, int reqHeight) {
    Bitmap bm = null;
    try{
        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(getActivity().getContentResolver().openInputStream(uri), null, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        bm = BitmapFactory.decodeStream(getActivity().getContentResolver().openInputStream(uri), null, options);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        Toast.makeText(getActivity().getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
    }
    return bm;
}


public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {
        if (width > height) {
            inSampleSize = Math.round((float)height / (float)reqHeight);
        } else {
            inSampleSize = Math.round((float)width / (float)reqWidth);
        }
    }
    return inSampleSize;
}

-

/*Get image orientation first from Exif info*/
public int getImageOrientation(Context context, Uri photoUri) {
    int orientation = getOrientationFromExif(photoUri);
    if(orientation <= 0) {
        orientation = getOrientationFromMediaStore(context, photoUri);
    }
    return orientation;
}

private int getOrientationFromExif(Uri photoUri) {
    int orientation = -1;
    try {
        ExifInterface exif = new ExifInterface(photoUri.getPath());
        int exifOrientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION,
                ExifInterface.ORIENTATION_NORMAL);

        switch (exifOrientation) {
            case ExifInterface.ORIENTATION_ROTATE_270:
                orientation = 270;
                break;
            case ExifInterface.ORIENTATION_ROTATE_180:
                orientation = 180;
                break;
            case ExifInterface.ORIENTATION_ROTATE_90:
                orientation = 90;
                break;
            case ExifInterface.ORIENTATION_NORMAL:
                orientation = 0;
                break;
            default:
                break;
        }
    } catch (IOException e) {
        Log.e("EXIF_ORIENTATION", "Unable to get image exif orientation", e);
    }
    return orientation;
}

/* normal landscape: 0
 * normal portrait: 90
 * upside-down landscape: 180
 * upside-down portrait: 270
 * image not found: -1
 */
private static int getOrientationFromMediaStore(Context context, Uri photoUri) {
    String[] projection = {MediaStore.Images.ImageColumns.ORIENTATION};
    Cursor cursor = context.getContentResolver().query(photoUri, projection, null, null, null);

    try {
        if (cursor.moveToFirst()) {
            return cursor.getInt(0);
        } else {
            return -1;
        }
    } finally {
        cursor.close();
    }
}

将NPE放在我想从exif数据中获取图像方向的行中，正好是从uri获取路径的地方：

ExifInterface exif = new ExifInterface(photoUri.getPath());

所以我知道它必须与路径有关。我已经发了几篇关于kitkat以不同格式返回路径的帖子。我尝试过不同的自定义getPath（）方法，但在调用Cursor时总是抛出NPE。

Answer 1

所以我知道它必须与路径有关。

那是因为它不是文件系统路径。 A Uri is not a file，当你在其他地方正确处理时，你在这里没有这样做。

您需要切换到可以处理InputStream的EXIF逻辑，例如this code culled from the AOSP Mms app。

相机图片Uri null路径

1 个答案: