计算Android平板电脑上的所有图片

Question

public int findAnyPictures(){
    int count = 0;
    final String[] columns = { MediaStore.Images.Media.DATA, MediaStore.Images.Media._ID };
    final String orderBy = MediaStore.Images.Media._ID;
    //Stores all the images from the gallery in Cursor
    Cursor cursor = getContentResolver().query(
            MediaStore.Images.Media.EXTERNAL_CONTENT_URI, columns, null,
            null, orderBy);
    //Total number of images
    if (cursor != null){
        count = cursor.getCount();
    }
    cursor.close();
    return count;
}

 public int findAnyVideos() {
        int vidsCount = 0;
        Uri uri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
        String[] projection = { MediaStore.Video.VideoColumns.DATA };
        Cursor cursor = mContext.getContentResolver().query(uri, projection, null, null, null);
        if (cursor != null) {
            vidsCount = cursor.getCount();
            cursor.close();
        }
        return vidsCount;
    }

当调用find any pictures时，它似乎抛出了一个运行时异常，我不知道为什么它会告诉我我没有适当的权限。我已经在android manifest中包含了它提到的权限，但我不知道grantUriPermission（）是什么？下面是堆栈跟踪

 

Answer 1

好吧，这告诉你问题所在

requires android.permission.READ_EXTERNAL_STORAGE

您必须在运行时请求Android API23+(Android6.0+)的权限。更多相关信息，请参见：https://developer.android.com/training/permissions/requesting.html

if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {

    requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
        REQUEST_CODE);
}

您将在OnRequestPermissionsResult中获得答案。