当然，我可以为你提供一个关于如何在Flutter中创建和使用自定义功能插件krunner的示例。由于krunner不是一个实际存在的Flutter插件（假设这是一个你自定义的插件名称），我将创建一个简单的Flutter插件示例，展示如何创建和使用一个自定义插件。

1. 创建Flutter插件

首先，我们需要创建一个Flutter插件。这可以通过Flutter命令行工具来完成：

flutter create --org com.example --template=plugin krunner

这将创建一个名为krunner的Flutter插件项目。

2. 编写插件代码（Dart部分）

进入插件项目目录，编辑lib/krunner.dart文件，定义插件的接口：

import 'dart:async';

import 'package:flutter/services.dart';

class Krunner {
  static const MethodChannel _channel = const MethodChannel('com.example.krunner');

  static Future<String?> get platformVersion async {
    final String? version = await _channel.invokeMethod('getPlatformVersion');
    return version;
  }

  // 添加你的自定义功能方法
  static Future<void> customFunction() async {
    try {
      await _channel.invokeMethod('customFunction');
    } on PlatformException catch (e) {
      throw e;
    }
  }
}

3. 编写插件代码（原生Android部分）

编辑android/src/main/java/com/example/krunner/KrunnerPlugin.java文件，实现插件的Android端功能：

package com.example.krunner;

import androidx.annotation.NonNull;

import io.flutter.embedding.engine.plugins.FlutterPlugin;
import io.flutter.embedding.engine.plugins.activity.ActivityAware;
import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
import io.flutter.plugin.common.MethodChannel.Result;
import io.flutter.embedding.android.FlutterActivity;

public class KrunnerPlugin implements FlutterPlugin, MethodCallHandler, ActivityAware {
  private MethodChannel channel;
  private FlutterActivity flutterActivity;

  @Override
  public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
    channel = new MethodChannel(flutterPluginBinding.getBinaryMessenger(), "com.example.krunner");
    channel.setMethodCallHandler(this);
  }

  @Override
  public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
    if (call.method.equals("getPlatformVersion")) {
      String version = android.os.Build.VERSION.RELEASE;
      result.success(version);
    } else if (call.method.equals("customFunction")) {
      // 执行自定义功能
      customFunction();
      result.success(null);
    } else {
      result.notImplemented();
    }
  }

  @Override
  public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
    channel.setMethodCallHandler(null);
  }

  private void customFunction() {
    // 在这里添加你的自定义功能代码
    // 例如：启动一个Activity，显示Toast，执行后台任务等
    // Toast.makeText(flutterActivity, "Custom Function Called", Toast.LENGTH_SHORT).show();
  }

  @Override
  public void onAttachedToActivity(ActivityPluginBinding binding) {
    flutterActivity = (FlutterActivity) binding.getActivity();
  }

  @Override
  public void onDetachedFromActivityForConfigChanges() {
    flutterActivity = null;
  }

  @Override
  public void onReattachedToActivityForConfigChanges(ActivityPluginBinding binding) {
    flutterActivity = (FlutterActivity) binding.getActivity();
  }

  @Override
  public void onDetachedFromActivity() {
    flutterActivity = null;
  }
}

4. 在Flutter应用中使用插件

在你的Flutter应用项目中，添加对插件的依赖（假设插件已经发布到pub.dev，或者你可以使用本地路径依赖）：

dependencies:
  flutter:
    sdk: flutter
  krunner:
    path: ../path/to/krunner  # 使用本地路径依赖

然后，在Dart代码中调用插件的方法：

import 'package:flutter/material.dart';
import 'package:krunner/krunner.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Krunner Plugin Example'),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Text('Running on: '),
              FutureBuilder<String?>(
                future: Krunner.platformVersion,
                builder: (context, snapshot) {
                  if (snapshot.hasData) {
                    return Text(snapshot.data!);
                  } else if (snapshot.hasError) {
                    return Text('${snapshot.error}');
                  }

                  // Show a loading spinner
                  return CircularProgressIndicator();
                },
              ),
              ElevatedButton(
                onPressed: () {
                  Krunner.customFunction();
                },
                child: Text('Call Custom Function'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

这个示例展示了如何创建一个Flutter插件，并在Flutter应用中调用插件的方法。你可以根据自己的需求，在插件的Android实现中添加具体的自定义功能代码。