我试图让公司从使用dart的条码中预先确定:

String extractCompanyPrefix(String gtin) {
  // Ensure the GTIN is a string to handle leading zeros and perform string operations
  String gtinStr = gtin.padLeft(14,  0 );

  String prefix = gtinStr.substring(0, 8);
  // remove leading zeros
  prefix = prefix.replaceFirst(RegExp(r ^0+ ),   );
  return prefix;
}

void main(List<String> arguments) {
  if (arguments.isEmpty) {
    print( Please provide a barcode. );
    return;
  }

  String barcode = arguments.first;
  String companyPrefix = extractCompanyPrefix(barcode);
  print( Company prefix: $companyPrefix );
}

❯ dart run dart/company_prefix_checker.dart 8710398527905
Company prefix: 8710398
❯ dart run dart/company_prefix_checker.dart 40111445
Company prefix: 40

这样做是否正确,会形成一个准确的GS1公司预设点?

Updated code to add @Terry Burton recommendations:

import  dart:convert ;
import  dart:io ;
import  package:path/path.dart  as path;
import  lib/application_identifiers.dart ;
import  lib/gcp_length.dart ;

Future<String> extractCompanyPrefix(
    String barcode, Map<String, int> gcpLengths) async {
  barcode = barcode.padLeft(12,  0 );
  for (var prefix in gcpLengths.keys) {
    if (barcode.startsWith(prefix)) {
      print(
           Found GCP prefix format: $prefix with length: ${gcpLengths[prefix]} );
      return barcode.substring(0, gcpLengths[prefix]!);
    }
  }

  var gai = await GS1ApplicationIdentifier.extract(barcode);


  var result = getGCPLength(gai.ai, barcode.substring(gai.ai.length));

  if (result !=  There is no matching value. Try GEPIR (https://gepir.gs1.org/) or contact local GS1 MO. ) {
    return result;
  }

  return "Invalid Barcode or GCP Not Found";
}

Future<Map<String, int>> loadGcpLengths(String filePath) async {
  try {
    var file = File(filePath);
    var contents = await file.readAsString();
    var jsonData = json.decode(contents);

    Map<String, int> gcpLengths = {};
    for (var entry in jsonData[ GCPPrefixFormatList ][ entry ]) {
      gcpLengths[entry[ prefix ]] = entry[ gcpLength ];
    }

    return gcpLengths;
  } catch (e) {
    throw Exception( Failed to load GCP length data from file: $e );
  }
}

void main(List<String> arguments) async {
  if (arguments.isEmpty) {
    print( Please provide a barcode. );
    return;
  }

  // Specify the path to your local  gcpprefixformatlist.json  file
  var jsonFilePath =
      path.join(Directory.current.path,  lib/gcpprefixformatlist.json );

  String barcode = arguments.first;
  try {
    Map<String, int> gcpLengths = await loadGcpLengths(jsonFilePath);
    String companyPrefix = await extractCompanyPrefix(barcode, gcpLengths);
    print( Company prefix: $companyPrefix );
  } catch (e) {
    print( Error: $e );
  }
}

lib/application_identifiers.dart:

import  dart:convert ;
import  dart:io ;

class GS1ApplicationIdentifier {
  final String ai;
  final String description;
  final String dataTitle;
  final bool fnc1Required;
  final String format;
  final String pattern;

  const GS1ApplicationIdentifier({
    required this.ai,
    required this.description,
    required this.dataTitle,
    required this.fnc1Required,
    required this.format,
    required this.pattern,
  });

  static Future<GS1ApplicationIdentifier> extract(String value) async {
    final applicationIdentifiers = await _loadApplicationIdentifiers();
    for (var ai in applicationIdentifiers) {
      if (value.startsWith(ai.ai)) {
        return ai;
      }
    }
    throw FormatException( Failed to get GS1 Application Identifier from $value. );
  }

  @override
  String toString() {
    return  ($ai) ;
  }

  static Future<List<GS1ApplicationIdentifier>> _loadApplicationIdentifiers() async {
    // final jsonString = await rootBundle.loadString( lib/application_identifiers.json );
    final jsonString = await File( lib/_application_identifiers.json ).readAsString();
    final List<dynamic> jsonList = json.decode(jsonString);
    return jsonList.map((json) => GS1ApplicationIdentifier.fromJson(json)).toList();
  }

  factory GS1ApplicationIdentifier.fromJson(Map<String, dynamic> json) {
    return GS1ApplicationIdentifier(
      ai: json[ ai ] as String,
      description: json[ description ] as String,
      dataTitle: json[ data_title ] as String,
      fnc1Required: json[ fnc1_required ] as bool,
      format: json[ format ] as String,
      pattern: json[ pattern ] as String,
    );
  }
}

lib/gcp_length.dart:

import  dart:convert ;
import  package:http/http.dart  as http;

final Map<String, String> gs1KeyRegEx = {
   00 : r ^(d{18})$ ,
   01 : r ^(d{14})$ ,
   253 : r ^(d{13})([x21-x22x25-x2Fx30-x39x3A-x3Fx41-x5Ax5Fx61-x7A]{0,17})$ ,
   255 : r ^(d{13})(d{0,12})$ ,
   401 : r ^([x21-x22x25-x2Fx30-x39x3A-x3Fx41-x5Ax5Fx61-x7A]{0,30})$ ,
   402 : r ^(d{17})$ ,
   414 : r ^(d{13})$ ,
   417 : r ^(d{13})$ ,
   8003 : r ^(d{14})([x21-x22x25-x2Fx30-x39x3A-x3Fx41-x5Ax5Fx61-x7A]{0,16})$ ,
   8004 : r ^([x21-x22x25-x2Fx30-x39x3A-x3Fx41-x5Ax5Fx61-x7A]{0,30})$ ,
   8006 : r ^(d{14})(d{2})(d{2})$ ,
   8010 : r ^([x23x2Dx2Fx30-x39x41-x5A]{0,30})$ ,
   8017 : r ^(d{18})$ ,
   8018 : r ^(d{18})$ ,
};

final Map<String, bool> keyStartsWithGCP = {
   00 : false,
   01 : false,
   253 : true,
   255 : true,
   401 : true,
   402 : true,
   414 : true,
   417 : true,
   8003 : false,
   8004 : true,
   8006 : false,
   8010 : true,
   8017 : true,
   8018 : true,
};


List<Map<String, dynamic>> gcpDict = [];

Future<void> fetchGcpData() async {
  final response = await http.get(Uri.parse( https://www.gs1.org/sites/default/files/docs/gcp_length/gcpprefixformatlist.json ));
  if (response.statusCode == 200) {
    final allGCPs = jsonDecode(response.body) as Map<String, dynamic>;
    gcpDict = List<Map<String, dynamic>>.from(allGCPs["GCPPrefixFormatList"]["entry"]);
  } else {
    throw Exception( Failed to fetch GCP Length Table data. );
  }
}

String getGCPLength(String aI, String gs1Key) {
  // Check if GS1 Key complies with its corresponding RegEx
  final regex = RegExp(gs1KeyRegEx[aI] ??   );
  if (!regex.hasMatch(gs1Key)) {
    return  The GS1 Key has an incorrect length or impermissible characters. ;
  }

  String gcpLength =   ;
  int j = 12;

  // Normalize input string
  if (keyStartsWithGCP[aI] ?? false) {
    gs1Key =  0  + gs1Key;
  }
  // Determine GCP length
  while (j > 2 && gcpLength.isEmpty) {
    for (var entry in gcpDict) {
      if (entry["prefix"].length == j && gs1Key.startsWith(entry["prefix"])) {
        gcpLength = entry["gcpLength"].toString();
        return gcpLength;
      }
    }
    j -= 1;
  }

  return  There is no matching value. Try GEPIR (https://gepir.gs1.org/) or contact local GS1 MO. ;
}

Future<void> main() async {
  try {
    await fetchGcpData();
    // Example usage
    String gcpLength = getGCPLength( 01 ,  01234567891234 );
    print(gcpLength);
  } catch (e) {
    print( Error: $e );
  }
}

❯ dart run company_prefix_checker.dart 8710398527905
Found GCP prefix format: 8710 with length: 7
Company prefix: 8710398
❯ dart run company_prefix_checker.dart 40111445
Found GCP prefix format: 00004 with length: 7
Company prefix: 0000401

该守则将检索。 https://www.gs1.org/docs/gcp_length/gcpprefixatlist.json 与其他智慧相匹配,将失败于reg和大赦国际。

这是正确的结果吗?