Flutter下载文件到本地

本示例中使用第三方库 flutter_downloader 使用Getx状态管理

在pubspec.yaml 引入插件

dependencies: flutter_downloader: ^1.11.6

在mian.dart中初始化插件

await FlutterDownloader.initialize(  debug:  true, // optional: set to false to disable printing logs to console (default: true)  ignoreSsl:  true // option: set to false to disable working with http links (default: false));

实际使用 文件详情controller

///声明接收端口final ReceivePort _port = ReceivePort();///下载状态bool isDown = false;///本地文件路径late String _saveLocalPath;///文件下载IDdynamic taskId = 0;///下载文档Future downloaderPdf() async {    if (filePath.isEmpty) {      print('文件地址为空');      return;    }    if (isDown) {      print('正在下载,请勿重复点击');      return;    }    ///loading    isDown = true;    print('下载中...');    taskId = await FlutterDownloader.enqueue(      url: filePath, ///文件地址      savedDir: _saveLocalPath,      fileName: '测试文档',      showNotification:          false, ///在状态栏显示下载进度(仅限Android)      openFileFromNotification:          false, ///点击通知打开下载的文件 (仅限Android)    );    ///合成本地路径 可以用来缓存 在下载记录中直接打开    localFilePath = '$_saveLocalPath/${fileDetails.filename}';    update();}///下载监听void _bindBackgroundIsolate() {    final isSuccess = IsolateNameServer.registerPortWithName(      _port.sendPort,      'downloader_send_port',    );    if (!isSuccess) {      _unbindBackgroundIsolate();      _bindBackgroundIsolate();      return;    }    _port.listen((dynamic data) async {      ///重新下载状态      isDown = false;      final taskId = (data as List)[0] as String;      final status = data[1];      final progress = data[2] as int;      if (status == 3) {        print('下载完成');        ///打开文件        ///删除下载任务        await FlutterDownloader.remove(          taskId: taskId,          shouldDeleteContent: true,        );      }      ///其他status 自行处理    });  }///释放监听void _unbindBackgroundIsolate() {  IsolateNameServer.removePortNameMapping('downloader_send_port');}///注册监听事件@pragma('vm:entry-point')static void downloadCallback(  String id,  int status,  int progress,) {  IsolateNameServer.lookupPortByName('downloader_send_port')      ?.send([id, status, progress]);}@overridevoid onInit() {  super.onInit();  WidgetsBinding.instance.addPostFrameCallback((_) async {    _bindBackgroundIsolate();    FlutterDownloader.registerCallback(downloadCallback);    ///获取文件存储路径    _saveLocalPath = await FileDirPath().prepareSaveDir();    update();  });}///页面关闭销毁监听@overrideonClose() {  _unbindBackgroundIsolate();  super.onClose();}

FileDirPath() 工具类 获取本地存储路径

导入对应插件

  # 文件  path_provider: ^2.1.0      # 权限请求  permission_handler: ^11.0.0  # 设备信息  device_info_plus: ^9.1.1

import 'dart:io';import 'package:device_info_plus/device_info_plus.dart';import 'package:path_provider/path_provider.dart';import 'package:permission_handler/permission_handler.dart';class FileDirPath {  late bool _permissionReady;  Future retryRequestPermission() async {    final hasGranted = await _checkPermission();    if (hasGranted) {      await prepareSaveDir();    }    _permissionReady = hasGranted;  }  ///获取文件保存路径  Future prepareSaveDir() async {    String localPath = (await _getSavedDir())!;    final savedDir = Directory(localPath);    if (!savedDir.existsSync()) {      await savedDir.create();    }    return localPath;  }  Future _getSavedDir() async {    String? externalStorageDirPath;    final Directory? downloadsDir;    if (Platform.isAndroid) {      try {        downloadsDir = await getDownloadsDirectory();        externalStorageDirPath = downloadsDir!.path;        print('externalStorageDirPath: $externalStorageDirPath');      } catch (err, st) {        print('failed to get downloads path: $err, $st');        final directory = await getExternalStorageDirectory();        externalStorageDirPath = directory?.path;      }    } else if (Platform.isIOS) {      // var dir = (await _dirsOnIOS)[0]; // temporary      // var dir = (await _dirsOnIOS)[1]; // applicationSupport      // var dir = (await _dirsOnIOS)[2]; // library      var dir = (await _dirsOnIOS)[3]; // applicationDocuments      //var dir = (await _dirsOnIOS)[4]; // downloads      dir ??= await getApplicationDocumentsDirectory();      externalStorageDirPath = dir.absolute.path;    }    return externalStorageDirPath;  }  Future get _dirsOnIOS async {    final temporary = await getTemporaryDirectory();    final applicationSupport = await getApplicationSupportDirectory();    final library = await getLibraryDirectory();    final applicationDocuments = await getApplicationDocumentsDirectory();    final downloads = await getDownloadsDirectory();    final dirs = [      temporary,      applicationSupport,      library,      applicationDocuments,      downloads    ];    return dirs;  }  Future _checkPermission() async {    if (Platform.isIOS) {      return true;    }    if (Platform.isAndroid) {      final info = await DeviceInfoPlugin().androidInfo;      if (info.version.sdkInt > 28) {        return true;      }      final status = await Permission.storage.status;      if (status == PermissionStatus.granted) {        return true;      }      final result = await Permission.storage.request();      return result == PermissionStatus.granted;    }    throw StateError('unknown platform');  }}

总结

1. flutter_downloader 集成配置参考插件官方文档
2. **Android 存储权限变更 : **Android13以下需要声明存储权限，以上则不需要默认已授权
3. 处理下载回调：flutter_downloader 插件提供了下载的回调函数，你可以利用这些回调来处理下载的状态变化，例如进度更新或下载完成。确保在你的应用中处理这些回调以提供更好的用户体验。
4. 错误处理： 考虑在下载过程中处理可能的错误情况，例如网络不稳定、存储空间不足等。提供清晰的错误信息以便用户能够了解问题并可能采取相应的措施。
5. 释放资源： 当你不再需要下载任务时，确保正确地释放资源，以避免潜在的内存泄漏