Android模拟器读取PDF崩溃：Lost Connection to Device与插件异常

针对你使用advanced_pdf_viewer插件在Android模拟器加载PDF时出现的「Lost Connection to Device」崩溃，以及Already closed、MissingPluginException错误，提供以下解决思路：

一、修复插件原生链接问题 #

• 执行flutter clean清理项目缓存，再运行flutter pub get重新拉取依赖
• 卸载模拟器上的现有APP，重新执行flutter run，确保插件的Android原生代码正确编译安装
• 检查android/app/build.gradle中的minSdkVersion，该插件要求最低SDK版本为21，若低于此版本需调整

二、优化PDF加载逻辑，避免流提前关闭 #

直接通过URL加载PDF可能导致网络流被提前释放，建议先将文件下载到本地再加载：

import 'package:path_provider/path_provider.dart';
import 'package:http/http.dart' as http;

class _FilePageState extends State<FilePage> {
  Future<File> _downloadFile(String url, String fileName) async {
    final directory = await getApplicationDocumentsDirectory();
    final file = File('${directory.path}/$fileName');
    final response = await http.get(Uri.parse(url));
    await file.writeAsBytes(response.bodyBytes);
    return file;
  }

  @override
  Widget build(BuildContext context) {
    return WillPopScope(
      onWillPop: () async => true,
      child: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.indigo[900],
          title: Text(widget.file!.name.split('.').first),
          centerTitle: true,
        ),
        body: FutureBuilder(
          future: _downloadFile(widget.file!.url, widget.file!.name),
          builder: (context, snapshot) {
            switch (snapshot.connectionState) {
              case ConnectionState.waiting:
              case ConnectionState.active:
                return const Center(child: CircularProgressIndicator());
              default:
                if (snapshot.hasError) {
                  return const Center(child: Text('文件下载失败'));
                }
                final localFile = snapshot.data as File;
                return FutureBuilder<PDFDocument>(
                  future: PDFDocument.fromFile(localFile),
                  builder: (ctx, pdfSnapshot) {
                    if (pdfSnapshot.connectionState == ConnectionState.waiting) {
                      return const Center(child: CircularProgressIndicator());
                    }
                    if (pdfSnapshot.hasError) {
                      return const Center(child: Text('PDF解析失败'));
                    }
                    return PDFViewer(document: pdfSnapshot.data!);
                  },
                );
            }
          },
        ),
      ),
    );
  }
}

需要在pubspec.yaml中添加依赖：

dependencies:
  path_provider: ^2.1.0
  http: ^1.1.0

三、替换为维护更活跃的PDF插件 #

advanced_pdf_viewer已长时间未更新，兼容性问题较多，推荐切换到flutter_pdfview（基于AndroidPdfViewer和iOS PDFKit）：

1. 添加依赖：

dependencies:
  flutter_pdfview: ^1.3.2

2. 修改加载代码：

import 'package:flutter_pdfview/flutter_pdfview.dart';

// 沿用上面的_downloadFile方法，加载时替换为PDFView
return PDFView(
  filePath: localFile.path,
  autoSpacing: true,
  pageFling: true,
  onError: (error) => print('加载错误: $error'),
  onPageError: (page, error) => print('第$page页错误: $error'),
);

四、检查Android权限配置 #

确保android/app/src/main/AndroidManifest.xml中添加了网络权限（加载网络PDF时需要）：

<uses-permission android:name="android.permission.INTERNET" />

内容的提问来源于stack exchange，提问作者learner