当然，以下是一个关于如何在Flutter中使用selectable插件来实现文本选择的代码案例。selectable是Flutter中的一个Widget，它允许用户选择文本并进行复制、粘贴等操作。虽然selectable并不是一个单独的插件，但它是Flutter Material库中内置的一个功能。

首先，确保你的Flutter项目已经设置好，并且已经导入了必要的Material库。然后，你可以按照以下步骤使用SelectableText来实现文本选择功能。

代码案例

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Selectable Text Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  final String longText = """
  Flutter is an open-source UI software development kit created by Google. It is used to develop applications for Android, iOS, Linux, Mac, Windows, and the web from a single codebase. Flutter's primary programming language is Dart.
  
  Flutter is designed to be as expressive and flexible as possible, and it offers a rich set of UI widgets that can be easily customized and reused. With Flutter, you can build natively compiled applications for mobile, web, and desktop from a single codebase.
  """;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Selectable Text Example'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              'This is a normal text that is not selectable.',
              style: TextStyle(fontSize: 18),
            ),
            SizedBox(height: 16),
            SelectableText(
              longText,
              style: TextStyle(fontSize: 18),
              toolbarOptions: ToolbarOptions(
                copy: true,
                selectAll: true,
                cut: true,
                paste: true,
                // You can customize the actions shown in the toolbar
              ),
              onSelectedTextChange: (TextSelection selection) {
                // This callback is triggered when the selected text changes
                print('Selected text: ${selection.textInside(longText)}');
              },
            ),
          ],
        ),
      ),
    );
  }
}

解释

1. 导入必要的库：

   import 'package:flutter/material.dart';
   

2. 定义应用入口：

   void main() {
     runApp(MyApp());
   }
   

3. 创建MyApp类：

   class MyApp extends StatelessWidget {
     @override
     Widget build(BuildContext context) {
       return MaterialApp(
         title: 'Selectable Text Example',
         theme: ThemeData(
           primarySwatch: Colors.blue,
         ),
         home: MyHomePage(),
       );
     }
   }
   

4. 创建MyHomePage类：

   • 定义一个长文本字符串。
   • 使用Scaffold来构建页面结构。
   • 使用Column来排列普通文本和可选择文本。
   • 使用SelectableText来创建可选择文本，并设置工具栏选项和选择文本改变时的回调。

class MyHomePage extends StatelessWidget {
  final String longText = """
  Flutter is an open-source UI software development kit created by Google. It is used to develop applications for Android, iOS, Linux, Mac, Windows, and the web from a single codebase. Flutter's primary programming language is Dart.
  
  Flutter is designed to be as expressive and flexible as possible, and it offers a rich set of UI widgets that can be easily customized and reused. With Flutter, you can build natively compiled applications for mobile, web, and desktop from a single codebase.
  """;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Selectable Text Example'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              'This is a normal text that is not selectable.',
              style: TextStyle(fontSize: 18),
            ),
            SizedBox(height: 16),
            SelectableText(
              longText,
              style: TextStyle(fontSize: 18),
              toolbarOptions: ToolbarOptions(
                copy: true,
                selectAll: true,
                cut: true,
                paste: true,
              ),
              onSelectedTextChange: (TextSelection selection) {
                print('Selected text: ${selection.textInside(longText)}');
              },
            ),
          ],
        ),
      ),
    );
  }
}

这样，你就可以在Flutter应用中实现文本选择功能了。用户可以选择文本，进行复制、粘贴等操作，并且你可以通过onSelectedTextChange回调来监听文本选择的变化。