Android文件未在Android Nougat设备上查看

Question

我是android新手，我在Android Nougat设备上打开pdf文件时遇到问题。我可以在棉花糖上打开pdf但不能在牛轧糖中打开

我的代码是这样的，

//regionOpen pdf file of Employee Induction with permission
    private void CopyReadAssets()
    {
        AssetManager assetManager = getResources().getAssets();

        InputStream in = null;
        OutputStream out = null;
        File file = new File(getFilesDir(), "Induction.pdf");
        try
        {
            copyFile(assetManager.open("Induction.pdf"), file);

        } catch (Exception e)
        {
            Log.e("tag", e.getMessage());
        }

        MimeTypeMap mime = MimeTypeMap.getSingleton();
        String ext = file.getName().substring(file.getName().lastIndexOf(".") + 1);
        String type = mime.getMimeTypeFromExtension(ext);
        try {
            Intent intent = new Intent();
            intent.setAction(Intent.ACTION_VIEW);

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                //intent.setDataAndType(getUri(file), type);

                Uri uri = Uri.parse("content://com.econnect.team.PdfContentProvider/"+"Induction.pdf");
               // Uri uri = FileProvider.getUriForFile(this, getPackageName() + ".PdfContentProvider", file);
                intent.setDataAndType(uri, type);

            } else {
                intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                intent.setDataAndType(Uri.fromFile(file), type);
                Log.e("Uri ", " "+ Uri.fromFile(file));
            }
            startActivityForResult(intent, 100);

        }catch (FileUriExposedException ex){
            Log.e("Uri ", "exception: "+ex.getMessage());
        }
        catch (ActivityNotFoundException anfe) {
            Toast.makeText(Menus.this, "No activity found to open this attachment.", Toast.LENGTH_LONG).show();

        }
    }

    private void copyFile(InputStream in, File f) throws IOException
    {
        try {
            FileOutputStream out = new FileOutputStream(f);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                out = openFileOutput(f.getName(), Context.MODE_PRIVATE);
            }
            else {
                out = openFileOutput(f.getName(), Context.MODE_WORLD_READABLE);
            }
            byte[] buffer = new byte[1024];
            int read;
            while ((read = in.read(buffer)) != -1) {
                out.write(buffer, 0, read);
            }
            in.close();
            out.close();
        }catch (Exception e){
            Log.e("copy file", e.getMessage());
        }

是否有人面临同样的问题，如果解决了这个问题，请帮助我。 提前谢谢。