解决PhotoPicker临时Uri重启失效问题：保存图片至应用目录

我在SQLite数据库中存储图片路径，使用PhotoPicker获取图片后通过setImageURI()显示，将Uri存入ImageView的Tag再保存到数据库。当前会话内能正常读取Uri显示图片，但PhotoPicker返回的临时Uri（例如content://media/picker/0/com.android.providers.media.photopicker/media/1000000033）在重启应用后会抛出java.lang.SecurityException: Calling uid ( 10190 ) does not have permission to access picker uri错误。

疑问 #

• 如何实现Uri的持久化访问？
• 是否需要将图片复制到应用可永久访问的目录（需包含权限说明及代码）？
• 能否直接永久访问该Uri？
• 有无更优方案？

初始代码 #

启动PhotoPicker的代码 #

private static void pickImage() {
    Intent intent = new Intent(MediaStore.ACTION_PICK_IMAGES);
    resultLauncher.launch(intent);
}

处理选择结果的代码 #

private void registerResult() {
    resultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), new ActivityResultCallback<ActivityResult>() {
        @Override
        public void onActivityResult(ActivityResult o) {
            try {
                Uri imageUri = o.getData().getData();
                imageView.setImageURI(imageUri);
                imageView.setTag(imageUri);

            } catch (Exception e) {
                e.printStackTrace();
                Toast.makeText(getContext(), "Error!", Toast.LENGTH_SHORT).show();
            }
        }
    });
}

从数据库读取Uri并显示的代码 #

stringUri = cursor.getString(5);
Uri imageUri = Uri.parse(stringUri);
alertBuilderPflanzeBild.setImageURI(imageUri);
alertBuilderPflanzeBild.setTag(imageUri);

我的解决方案 #

保存图片到应用目录的代码 #

private static String savePic (ImageView imageView, String subfolder, String pictureName) {
    // subfolder: Pflanzen, Rezepte, ..
    BitmapDrawable drawable = (BitmapDrawable) imageView.getDrawable();
    Bitmap bitmap = drawable.getBitmap();
    try {
        File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM)+"/Pictures/[APP_NAME]/"+subfolder+"/",pictureName+".jpg");

        if (!file.exists()) {
            Log.d(TAG, "Folder '" + file.toString() + "' doesn't exist, creating it...");
            boolean rv = Objects.requireNonNull(file.getParentFile()).mkdir();
            Log.d(TAG, "Folder creation " + ( rv ? "success" : "failed"));
        } else {
            Log.d(TAG, "Folder already exists.");
        }

        FileOutputStream out = new FileOutputStream(file);
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
        out.flush();
        out.close();
        return file.getAbsolutePath();

    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return null;
}

从本地路径读取图片的代码 #

private static Bitmap getPic (String path) {
    File file = new File(path);
    Bitmap bmap=BitmapFactory.decodeFile(file.getAbsolutePath());
    //imageView.setImageBitmap(bmap);
    return bmap;
}

结论 #

先通过临时Uri加载图片到ImageView，再调用savePic()将图片保存到应用专属目录，把返回的绝对路径存入数据库；后续通过getPic()从路径读取图片，实现持久化访问。

内容的提问来源于stack exchange，提问作者timmy