Flutter中怎样加载并预览本地的html文件的方法

   assets:
  - assets/images/
  - assets/files/

  webview_flutter: ^0.3.15+1
  // 具体版本请查看官网

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';

class AgreementPage extends StatefulWidget {
 @override
 _AgreementPageState createState() => _AgreementPageState();
}

class _AgreementPageState extends State<AgreementPage> {
 WebViewController _webViewController;
 String filePath = 'assets/files/agreement.html';

 @override
 Widget build(BuildContext context) {
  return Scaffold(
   appBar: AppBar(title: Text('享你来服务条款')),
   body: WebView(
    initialUrl: '',
    javascriptMode: JavascriptMode.unrestricted,
    onWebViewCreated: (WebViewController webViewController) {
     _webViewController = webViewController;
     _loadHtmlFromAssets();
    },
   )
  );
 }

  _loadHtmlFromAssets() async {
  String fileHtmlContents = await rootBundle.loadString(filePath);
  _webViewController.loadUrl(Uri.dataFromString(fileHtmlContents,
      mimeType: 'text/html', encoding: Encoding.getByName('utf-8'))
    .toString());
 }
}