Flutter自定义User-Agent插件webview_useragent的使用

Flutter自定义User-Agent插件webview_useragent的使用

webview_useragent 是一个用于获取原生WebView UserAgent的Flutter插件。通过此插件，你可以在Flutter应用中获取设备的User-Agent信息。

完整示例Demo

以下是一个完整的示例代码，展示了如何在Flutter应用中使用webview_useragent插件来获取和显示User-Agent信息。

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

import 'package:flutter/services.dart';
import 'package:webview_useragent/webview_useragent.dart';

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

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  [@override](/user/override)
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _platformUserAgent = 'Unknown';
  final _webviewUserAgentPlugin = WebviewUserAgent();

  [@override](/user/override)
  void initState() {
    super.initState();
    initPlatformState();
  }

  // 异步方法，初始化平台状态
  Future<void> initPlatformState() async {
    String platformUserAgent;
    // 可能会抛出PlatformException，因此我们使用try/catch语句来处理
    // 同时处理消息可能返回null的情况
    try {
      platformUserAgent = 
          await _webviewUserAgentPlugin.getPlatformUserAgent() ?? 'Unknown platform UserAgent';
    } on PlatformException {
      platformUserAgent = 'Failed to get platform UserAgent.';
    }

    // 如果在这个异步调用过程中，组件已经从树中移除，则应丢弃回复而不是调用setState
    if (!mounted) return;

    // 更新UI状态
    setState(() {
      _platformUserAgent = platformUserAgent;
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('User-Agent 插件示例应用'),
        ),
        body: Center(
          child: Text(_platformUserAgent),
        ),
      ),
    );
  }
}

代码解释

• 导入必要的包:

  import 'package:flutter/material.dart';
  import 'dart:async';
  import 'package:flutter/services.dart';
  import 'package:webview_useragent/webview_useragent.dart';
  

• 主函数入口:

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

• 定义主应用类:

  class MyApp extends StatefulWidget {
    const MyApp({super.key});
  
    [@override](/user/override)
    State<MyApp> createState() => _MyAppState();
  }
  

• 定义状态管理类:

  class _MyAppState extends State<MyApp> {
    String _platformUserAgent = 'Unknown';
    final _webviewUserAgentPlugin = WebviewUserAgent();
  
    [@override](/user/override)
    void initState() {
      super.initState();
      initPlatformState();
    }
  

• 初始化平台状态:

  Future<void> initPlatformState() async {
    String platformUserAgent;
    try {
      platformUserAgent = 
          await _webviewUserAgentPlugin.getPlatformUserAgent() ?? 'Unknown platform UserAgent';
    } on PlatformException {
      platformUserAgent = 'Failed to get platform UserAgent.';
    }
  
    if (!mounted) return;
  
    setState(() {
      _platformUserAgent = platformUserAgent;
    });
  }
  

• 构建UI:

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('User-Agent 插件示例应用'),
        ),
        body: Center(
          child: Text(_platformUserAgent),
        ),
      ),
    );
  }