如何从本地资源文件夹在flutter webview中注入自定义css和js文件

flutter:
  assets:
    - assets/

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

class MyWebView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return InAppWebView(
      initialUrlRequest: URLRequest(
        url: Uri.parse("https://example.com"),
      ),
      initialOptions: InAppWebViewGroupOptions(
        android: AndroidInAppWebViewOptions(
          useHybridComposition: true,
        ),
      ),
      onWebViewCreated: (controller) {
        // 注入CSS文件
        controller.injectCssCode("""
          // CSS代码
        """);

        // 注入JS文件
        controller.injectJavascriptCode("""
          // JS代码
        """);
      },
    );
  }
}