Flutter 断言失败，但可以使用资产

Question

I have been trying to perform an ocr using the Tesseract ocr library. However, withing the TesseractOcr.extractText() method it performs an assertion to check if the image exists which always fail. To confirm that I have added the image properly I have added an Image widget which works perfectly fine. Is there anything I missed here?.

Screen shot

main.dart

import 'package:flutter/services.dart';
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:tesseract_ocr/tesseract_ocr.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
 @override
 _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
 String _extractText = 'Unknown';

 @override
 void initState() {
   super.initState();
   initPlatformState();
 }

 // Platform messages are asynchronous, so we initialize in an async method.
 Future<void> initPlatformState() async {
   String extractText;
   try {
     
     extractText = await TesseractOcr.extractText('assests/images/test.jpeg', language: "eng");
   } on PlatformException {
     extractText = 'Failed to extract text';
   }

   if (!mounted) return;

   setState(() {
     _extractText = extractText;
   });
 }

 @override
 Widget build(BuildContext context) {
   return MaterialApp(
     home: Scaffold(
         appBar: AppBar(
           title: const Text('Tesseract OCR'),
         ),
         body: Column(
           children: <Widget>[
             Center(
               child: Text('Detected Texts: $_extractText\n'),
             ),
             Image.asset('assests/images/test.jpeg', width:300,height:100)
           ],
         )),
   );
 }
}

pubspec.yaml

name: hello_world
description: A new Flutter project.

# The following line prevents the package from being accidentally published to
# pub.dev using `pub publish`. This is preferred for private packages.
publish_to: "none" # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  tesseract_ocr: ^0.3.0

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.3

dev_dependencies:
  flutter_test:
    sdk: flutter

  # For information on the generic Dart part of this file, see the
  # following page: https://dart.dev/tools/pub/pubspec
  cupertino_icons: ^0.1.2
  flutter_spinkit: ^4.1.2+1
  file_picker: ^1.9.0+1
# The following section is specific to Flutter.
flutter:
  assets:
    - assests/images/
    - assests/tessdata/
    - assests/
  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true
  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg
  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.
  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages
  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

TesseractOcr.extractText() method

  static Future<String> extractText(String imagePath, {String language}) async {
    assert(await File(imagePath).exists(), true);
    final String tessData = await _loadTessData();
    final String extractText = await _channel.invokeMethod('extractText', <String, dynamic>{
      'imagePath': imagePath,
      'tessData': tessData,
      'language': language,
    });
    return extractText;
  }

Answer 1

Your 'assets' folder spelling is wrong.

Not:

• assests/images/
• assests/tessdata/
• assests/

Should be:

• assets/images/
• assets/tessdata/
• assets/