Flutter中如何获取内外存储的所有PDF文件并实现点击全屏打开？

Hey there! Let's build this feature step by step—we'll scan both internal and external storage for all PDF files, display them in a list, and open any selected file in a full-screen dialog. Here's a practical, working guide with code you can adapt:

Step 1: Add Required Dependencies #

First, add these packages to your pubspec.yaml to handle permissions, storage access, and PDF viewing:

dependencies:
  flutter:
    sdk: flutter
  permission_handler: ^10.2.0
  flutter_pdfview: ^1.2.1
  path_provider: ^2.0.15
  device_info_plus: ^9.0.2

Run flutter pub get to install them.

Step 2: Request Storage Permissions #

We need permissions to access device storage. Create a helper function to handle this (works for Android and iOS):

import 'package:permission_handler/permission_handler.dart';
import 'package:device_info_plus/device_info_plus.dart';

Future<bool> requestStoragePermission() async {
  PermissionStatus status;
  if (Platform.isAndroid) {
    final androidInfo = await DeviceInfoPlugin().androidInfo;
    if (androidInfo.version.sdkInt >= 33) {
      status = await Permission.manageExternalStorage.request();
    } else {
      status = await Permission.storage.request();
    }
  } else if (Platform.isIOS) {
    status = await Permission.photosAddOnly.request();
  } else {
    status = PermissionStatus.granted;
  }
  return status.isGranted;
}

Don't forget to declare permissions in native config files:

• Android: Add these to AndroidManifest.xml inside the <manifest> tag:

  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" android:maxSdkVersion="32"/>
  <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
  

• iOS: Add this to Info.plist:

  <key>NSDocumentsFolderUsageDescription</key>
  <string>Need access to documents to scan PDF files</string>
  

Step 3: Scan for All PDF Files #

Next, write a function to fetch PDFs. For Android 10+, we use MediaStore (since direct directory access is restricted), and traverse directories for older versions/iOS:

import 'dart:io';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';

Future<List<File>> getAllPdfFiles() async {
  List<File> pdfFiles = [];
  if (Platform.isAndroid) {
    final androidInfo = await DeviceInfoPlugin().androidInfo;
    // Handle Android 10+ with MediaStore
    if (androidInfo.version.sdkInt >= 29) {
      final database = await openDatabase(
        '/data/data/com.android.providers.media/databases/external.db',
        readOnly: true,
      );
      final result = await database.rawQuery('''
        SELECT _data FROM files WHERE mime_type = 'application/pdf'
      ''');
      for (var row in result) {
        final path = row['_data'] as String;
        if (await File(path).exists()) pdfFiles.add(File(path));
      }
      await database.close();
    } else {
      // Traverse external storage for older Android versions
      final externalDir = await getExternalStorageDirectory();
      if (externalDir != null) pdfFiles.addAll(await _scanDirForPdfs(externalDir));
    }
    // Scan internal app storage
    final internalDir = await getApplicationDocumentsDirectory();
    pdfFiles.addAll(await _scanDirForPdfs(internalDir));
  } else if (Platform.isIOS) {
    // Scan iOS documents directory
    final docsDir = await getApplicationDocumentsDirectory();
    pdfFiles.addAll(await _scanDirForPdfs(docsDir));
  }
  // Remove duplicate files
  return pdfFiles.toSet().toList();
}

Future<List<File>> _scanDirForPdfs(Directory dir) async {
  List<File> pdfs = [];
  try {
    await for (var entity in dir.list(recursive: true)) {
      if (entity is File && entity.path.endsWith('.pdf')) pdfs.add(entity);
    }
  } catch (e) {
    print('Error scanning directory: $e');
  }
  return pdfs;
}

Step 4: Display the PDF List #

Build the UI to show the scanned PDFs in a list:

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

  @override
  State<PdfListScreen> createState() => _PdfListScreenState();
}

class _PdfListScreenState extends State<PdfListScreen> {
  List<File> _pdfFiles = [];
  bool _isLoading = true;

  @override
  void initState() {
    super.initState();
    _loadPdfFiles();
  }

  Future<void> _loadPdfFiles() async {
    final hasPermission = await requestStoragePermission();
    if (hasPermission) _pdfFiles = await getAllPdfFiles();
    setState(() => _isLoading = false);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('All PDF Files')),
      body: _isLoading
          ? const Center(child: CircularProgressIndicator())
          : _pdfFiles.isEmpty
              ? const Center(child: Text('No PDF files found'))
              : ListView.builder(
                  itemCount: _pdfFiles.length,
                  itemBuilder: (context, index) {
                    final file = _pdfFiles[index];
                    final fileName = file.path.split('/').last;
                    return ListTile(
                      title: Text(fileName),
                      subtitle: Text(file.path),
                      onTap: () => _openPdfInFullScreen(file),
                    );
                  },
                ),
    );
  }
}

Step 5: Open PDF in Full-Screen Dialog #

Add a function to open the selected PDF in a full-screen dialog:

import 'package:flutter_pdfview/flutter_pdfview.dart';

void _openPdfInFullScreen(File pdfFile) {
  showDialog(
    context: context,
    barrierDismissible: false,
    builder: (context) => Dialog(
      insetPadding: EdgeInsets.zero,
      child: SizedBox(
        width: MediaQuery.of(context).size.width,
        height: MediaQuery.of(context).size.height,
        child: Stack(
          children: [
            PDFView(
              filePath: pdfFile.path,
              enableSwipe: true,
              swipeHorizontal: true,
              pageFling: true,
              onError: (error) {
                print('PDF Error: $error');
                Navigator.pop(context);
              },
            ),
            // Add a close button
            Positioned(
              top: 20,
              right: 20,
              child: IconButton(
                icon: const Icon(Icons.close, color: Colors.white),
                onPressed: () => Navigator.pop(context),
              ),
            ),
          ],
        ),
      ),
    ),
  );
}

Quick Notes: #

• Android 10+ Scoped Storage: The MediaStore path might vary slightly across devices—test on multiple devices to handle edge cases.
• iOS Restrictions: iOS limits access to certain directories; you can add access to the Downloads folder by enabling appropriate capabilities in Xcode.
• Error Handling: Expand the try/catch blocks to handle cases like deleted files or permission denials gracefully.

内容的提问来源于stack exchange，提问作者Tushar Pol