Flutter字符集转换插件charset_converter的使用
Flutter字符集转换插件charset_converter的使用
简介
charset_converter 是一个用于在Flutter中编码和解码字符集的插件。它利用平台内置的转换器，无需额外的字符集映射或像iconv这样的完整库，从而节省了应用程序包的大小。该插件不包含任何Dart依赖项，但依赖于平台支持。最初是为了帮助解决StackOverflow上的一个问题以及Dart对GBK、Big5、Windows-125X或ISO-8859-XX等特定字符集的支持不足而创建。
使用方法
编码
Uint8List encoded = await CharsetConverter.encode("windows1250", "Polish has óśćł");
解码
String decoded = await CharsetConverter.decode("windows1250",
Uint8List.fromList([0x43, 0x7A, 0x65, 0x9C, 0xE6])); // Hello (Cześć) in Polish
获取可用字符集列表
List<String> charsets = await CharsetConverter.availableCharsets();
注意： 即使某个字符集不在列表中，它仍然可能工作。这是因为函数并不返回所有别名的完整列表。例如，在iOS上，TIS620不在列表中，但ISO 8859-11（实际上是TIS620的别名）是存在的。要检查字符集是否可用，请使用 CharsetConverter.checkAvailability。
检查字符集是否可用
bool isAvailable = await CharsetConverter.checkAvailability("EUC-KR");
示例代码
以下是一个完整的示例应用，展示了如何使用 charset_converter 插件进行字符集的编码、解码和可用性检查：
import 'dart:developer';
import 'package:flutter/material.dart';
import 'package:charset_converter/charset_converter.dart';
import 'package:flutter/services.dart';
void main() => runApp(const MyApp());
const gap = SizedBox(
width: 8,
height: 8,
);
const horizontalPadding = EdgeInsets.symmetric(horizontal: 8);
enum ConversionMode { encode, decode, checkAvailability }
class MyApp extends StatefulWidget {
const MyApp({Key? key}) : super(key: key);
@override
MyAppState createState() => MyAppState();
}
class MyAppState extends State<MyApp> {
String? output;
bool isLoading = false;
ConversionMode mode = ConversionMode.encode;
Uint8List _parseByteList(String input) {
final parts = input.split(',');
final parsedBytes = parts.map((e) => int.tryParse(e)).toList();
if (parsedBytes.contains(null)) {
throw FormatException("Could not parse $input as list of bytes");
}
return Uint8List.fromList(parsedBytes.cast<int>());
}
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: const Text('CharsetConverter example'),
),
body: Builder(builder: (context) {
return Column(
children: [
Padding(
padding: horizontalPadding,
child: TextField(
decoration: const InputDecoration(
label: Text("Input"),
hintText: "Text or list of bytes like 65, 66, 67",
border: OutlineInputBorder(),
),
onChanged: (value) {
setState(() {
output = null;
});
},
),
),
gap,
Padding(
padding: horizontalPadding,
child: TextField(
decoration: const InputDecoration(
label: Text("Charset"),
hintText: "Charset name like windows1250",
border: OutlineInputBorder(),
),
onChanged: (value) {
setState(() {
output = null;
});
},
),
),
gap,
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
ElevatedButton(
onPressed: () async {
final inputController = TextEditingController();
final charsetController = TextEditingController();
final input = inputController.text;
final charset = charsetController.text;
setState(() {
output = null;
isLoading = true;
});
try {
if (mode == ConversionMode.encode) {
final result = await CharsetConverter.encode(charset, input);
setState(() {
output = result.join(', ');
});
} else if (mode == ConversionMode.decode) {
final result = await CharsetConverter.decode(
charset, _parseByteList(input));
setState(() {
output = result;
});
} else if (mode == ConversionMode.checkAvailability) {
final result =
await CharsetConverter.checkAvailability(charset);
setState(() {
output = result ? "Available" : "Not found";
});
} else {
throw UnimplementedError("Unknown conversion mode");
}
} on PlatformException catch (e) {
log(e.toString());
ScaffoldMessenger.of(context).showSnackBar(
const SnackBar(
content: Text("Something went wrong"),
),
);
} finally {
setState(() {
isLoading = false;
});
}
},
child: const Text("Encode"),
),
ElevatedButton(
onPressed: () async {
final inputController = TextEditingController();
final charsetController = TextEditingController();
final input = inputController.text;
final charset = charsetController.text;
setState(() {
output = null;
isLoading = true;
});
try {
final result = await CharsetConverter.decode(
charset, _parseByteList(input));
setState(() {
output = result;
});
} on PlatformException catch (e) {
log(e.toString());
ScaffoldMessenger.of(context).showSnackBar(
const SnackBar(
content: Text("Something went wrong"),
),
);
} finally {
setState(() {
isLoading = false;
});
}
},
child: const Text("Decode"),
),
ElevatedButton(
onPressed: () async {
final charsetController = TextEditingController();
final charset = charsetController.text;
setState(() {
output = null;
isLoading = true;
});
try {
final result =
await CharsetConverter.checkAvailability(charset);
setState(() {
output = result ? "Available" : "Not found";
});
} on PlatformException catch (e) {
log(e.toString());
ScaffoldMessenger.of(context).showSnackBar(
const SnackBar(
content: Text("Something went wrong"),
),
);
} finally {
setState(() {
isLoading = false;
});
}
},
child: const Text("Check if available"),
),
ElevatedButton(
onPressed: () async {
setState(() {
output = null;
isLoading = true;
});
final charsets =
await CharsetConverter.availableCharsets();
setState(() {
output = charsets.join("\n");
isLoading = false;
});
},
child: const Text("Get available charsets"),
)
],
),
gap,
if (isLoading)
const Center(child: CircularProgressIndicator()),
if (output != null)
Padding(
padding: horizontalPadding,
child: SelectableText(
output!,
key: const Key("output"),
),
),
gap,
],
);
}),
),
);
}
}
这个示例应用提供了一个简单的界面，用户可以输入文本或字节列表以及字符集名称，并选择进行编码、解码、检查字符集可用性或获取所有可用字符集的操作。希望这能帮助你更好地理解和使用 charset_converter 插件。
更多关于Flutter字符集转换插件charset_converter的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html
