flutter_downloader文件下载插件
2024-05-11 07:25:11
使用前需要初始化
await FlutterDownloader.initialize(debug: debug);
import 'dart:isolate';
import 'dart:ui';
import 'dart:async';
import 'dart:io';import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:flutter_downloader/flutter_downloader.dart';
import 'package:permission_handler/permission_handler.dart';const debug = true;class FlutterDownloaderDemo extends StatefulWidget with WidgetsBindingObserver {@override_FlutterDownloaderDemoState createState() => new _FlutterDownloaderDemoState();
}class _FlutterDownloaderDemoState extends State<FlutterDownloaderDemo> {final _documents = [{'name': 'Learning Android Studio','link': 'http://barbra-coco.dyndns.org/student/learning_android_studio.pdf'},{'name': 'Android Programming Cookbook','link': 'http://enos.itcollege.ee/~jpoial/allalaadimised/reading/Android-Programming-Cookbook.pdf'},{'name': 'iOS Programming Guide','link': 'http://darwinlogic.com/uploads/education/iOS_Programming_Guide.pdf'},{'name': 'Objective-C Programming (Pre-Course Workbook','link': 'https://www.bignerdranch.com/documents/objective-c-prereading-assignment.pdf'},];final _images = [{'name': 'Arches National Park','link': 'https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fb.zol-img.com.cn%2Fsjbizhi%2Fimages%2F5%2F320x510%2F137760363184.jpg&refer=http%3A%2F%2Fb.zol-img.com.cn&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1624849370&t=fb018c3ff3c939cf5dd5fb52210bec7d'},{'name': 'Canyonlands National Park','link': 'https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fimg.zcool.cn%2Fcommunity%2F01251f57c36e000000012e7e27412c.jpg&refer=http%3A%2F%2Fimg.zcool.cn&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1624849370&t=609a5f51ecaa96b8e39b8747ea2fa2b2'},{'name': 'Death Valley National Park','link': 'https://upload.wikimedia.org/wikipedia/commons/b/b2/Sand_Dunes_in_Death_Valley_National_Park.jpg'},{'name': 'Gates of the Arctic National Park and Preserve','link': 'https://upload.wikimedia.org/wikipedia/commons/e/e4/GatesofArctic.jpg'}];final _videos = [{'name': 'Big Buck Bunny','link': 'http://commondatastorage.flutter-io.cn/gtv-videos-bucket/sample/BigBuckBunny.mp4'},{'name': 'Elephant Dream','link': 'http://commondatastorage.flutter-io.cn/gtv-videos-bucket/sample/ElephantsDream.mp4'}];//任务列表List<_TaskInfo> _tasks;//项目列表List<_ItemHolder> _items;//是否在加载bool _isLoading;//用户是否同意权限bool _permissionReady;//存储路径String _localPath;//接收端口ReceivePort _port = ReceivePort();@overridevoid initState() {super.initState();_bindBackgroundIsolate();//注册下载回调FlutterDownloader.registerCallback(downloadCallback);_isLoading = true;_permissionReady = false;//加载_prepare();}@overridevoid dispose() {_unbindBackgroundIsolate();super.dispose();}void _bindBackgroundIsolate() {bool isSuccess = IsolateNameServer.registerPortWithName(_port.sendPort, 'downloader_send_port');if (!isSuccess) {_unbindBackgroundIsolate();_bindBackgroundIsolate();return;}//注册接收端口监听_port.listen((dynamic data) {if (debug) {print('UI Isolate Callback: $data');}//任务idString id = data[0];//任务状态DownloadTaskStatus status = data[1];//任务进度int progress = data[2];if (_tasks != null && _tasks.isNotEmpty) {//查找对应的下载任务final task = _tasks.firstWhere((task) => task.taskId == id);if (task != null) {//更新下载任务状态和进度setState(() {task.status = status;task.progress = progress;});}}});}//释放资源void _unbindBackgroundIsolate() {IsolateNameServer.removePortNameMapping('downloader_send_port');}//下载回调static void downloadCallback(String id, DownloadTaskStatus status, int progress) {if (debug) {print('Background Isolate Callback: task ($id) is in status ($status) and process ($progress)');}final SendPort send = IsolateNameServer.lookupPortByName('downloader_send_port');send.send([id, status, progress]);}@overrideWidget build(BuildContext context) {return new Scaffold(appBar: new AppBar(title: new Text('flutter_downloader文件下载'),),body: Builder(builder: (context) => _isLoading? new Center(child: new CircularProgressIndicator(),): _permissionReady? _buildDownloadList(): _buildNoPermissionWarning()),);}Widget _buildDownloadList() => Container(child: ListView(padding: const EdgeInsets.symmetric(vertical: 16.0),children: _items.map((item) => item.task == null? _buildListSection(item.name): DownloadItem(data: item,onItemClick: (task) {_openDownloadedFile(task).then((success) {if (!success) {Scaffold.of(context).showSnackBar(SnackBar(content: Text('Cannot open this file')));}});},onAtionClick: (task) {if (task.status == DownloadTaskStatus.undefined) {_requestDownload(task);} else if (task.status == DownloadTaskStatus.running) {_pauseDownload(task);} else if (task.status == DownloadTaskStatus.paused) {_resumeDownload(task);} else if (task.status == DownloadTaskStatus.complete) {_delete(task);} else if (task.status == DownloadTaskStatus.failed) {_retryDownload(task);}},)).toList(),),);Widget _buildListSection(String title) => Container(padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),child: Text(title,style: TextStyle(fontWeight: FontWeight.bold, color: Colors.blue, fontSize: 18.0),),);Widget _buildNoPermissionWarning() => Container(child: Center(child: Column(mainAxisSize: MainAxisSize.min,crossAxisAlignment: CrossAxisAlignment.center,children: [Padding(padding: const EdgeInsets.symmetric(horizontal: 24.0),child: Text('Please grant accessing storage permission to continue -_-',textAlign: TextAlign.center,style: TextStyle(color: Colors.blueGrey, fontSize: 18.0),),),SizedBox(height: 32.0,),FlatButton(onPressed: () {_checkPermission().then((hasGranted) {setState(() {_permissionReady = hasGranted;});});},child: Text('Retry',style: TextStyle(color: Colors.blue,fontWeight: FontWeight.bold,fontSize: 20.0),))],),),);void _requestDownload(_TaskInfo task) async {task.taskId = await FlutterDownloader.enqueue(url: task.link,headers: {"auth": "test_for_sql_encoding"},savedDir: _localPath,showNotification: true,openFileFromNotification: true);}void _cancelDownload(_TaskInfo task) async {await FlutterDownloader.cancel(taskId: task.taskId);}void _pauseDownload(_TaskInfo task) async {await FlutterDownloader.pause(taskId: task.taskId);}void _resumeDownload(_TaskInfo task) async {String newTaskId = await FlutterDownloader.resume(taskId: task.taskId);task.taskId = newTaskId;}void _retryDownload(_TaskInfo task) async {String newTaskId = await FlutterDownloader.retry(taskId: task.taskId);task.taskId = newTaskId;}Future<bool> _openDownloadedFile(_TaskInfo task) {if (task != null) {return FlutterDownloader.open(taskId: task.taskId);} else {return Future.value(false);}}void _delete(_TaskInfo task) async {await FlutterDownloader.remove(taskId: task.taskId, shouldDeleteContent: true);await _prepare();setState(() {});}Future<bool> _checkPermission() async {if (Platform.isAndroid) {final status = await Permission.storage.status;if (status != PermissionStatus.granted) {final result = await Permission.storage.request();if (result == PermissionStatus.granted) {return true;}} else {return true;}} else {return true;}return false;}//加载任务、权限、下载项目等Future<Null> _prepare() async {//获取全部下载任务final tasks = await FlutterDownloader.loadTasks();int count = 0;_tasks = [];_items = [];//添加下载任务_tasks.addAll(_documents.map((document) => _TaskInfo(name: document['name'], link: document['link'])));_items.add(_ItemHolder(name: 'Documents'));for (int i = count; i < _tasks.length; i++) {_items.add(_ItemHolder(name: _tasks[i].name, task: _tasks[i]));count++;}//添加下载任务_tasks.addAll(_images.map((image) => _TaskInfo(name: image['name'], link: image['link'])));_items.add(_ItemHolder(name: 'Images'));for (int i = count; i < _tasks.length; i++) {_items.add(_ItemHolder(name: _tasks[i].name, task: _tasks[i]));count++;}//添加下载任务_tasks.addAll(_videos.map((video) => _TaskInfo(name: video['name'], link: video['link'])));_items.add(_ItemHolder(name: 'Videos'));for (int i = count; i < _tasks.length; i++) {_items.add(_ItemHolder(name: _tasks[i].name, task: _tasks[i]));count++;}tasks?.forEach((task) {for (_TaskInfo info in _tasks) {if (info.link == task.url) {info.taskId = task.taskId;info.status = task.status;info.progress = task.progress;}}});//权限是否就绪_permissionReady = await _checkPermission();_localPath = (await _findLocalPath()) + Platform.pathSeparator + 'Download';//savedDir下载文件存储位置final savedDir = Directory(_localPath);//判断目录是否存在bool hasExisted = await savedDir.exists();if (!hasExisted) {//创建目录savedDir.create();}setState(() {_isLoading = false;});}//获取存储目录地址Future<String> _findLocalPath() async {final directory = Platform.isAndroid//getExternalStorageDirectory,获取存储目录（android）? await (getExternalStorageDirectory() as FutureOr<Directory>)//获取存储目录: await getApplicationDocumentsDirectory();return directory.path;}
}
//下载项列表行
class DownloadItem extends StatelessWidget {final _ItemHolder data;final Function(_TaskInfo) onItemClick;final Function(_TaskInfo) onAtionClick;DownloadItem({this.data, this.onItemClick, this.onAtionClick});@overrideWidget build(BuildContext context) {return Container(padding: const EdgeInsets.only(left: 16.0, right: 8.0),child: InkWell(onTap: data.task.status == DownloadTaskStatus.complete? () {onItemClick(data.task);}: null,child: Stack(children: <Widget>[Container(width: double.infinity,height: 64.0,child: Row(crossAxisAlignment: CrossAxisAlignment.center,children: <Widget>[Expanded(child: Text(data.name,maxLines: 1,softWrap: true,overflow: TextOverflow.ellipsis,),),Padding(padding: const EdgeInsets.only(left: 8.0),child: _buildActionForTask(data.task),),],),),data.task.status == DownloadTaskStatus.running ||data.task.status == DownloadTaskStatus.paused? Positioned(left: 0.0,right: 0.0,bottom: 0.0,child: LinearProgressIndicator(value: data.task.progress / 100,),): Container()].where((child) => child != null).toList(),),),);}//构建任务行Widget _buildActionForTask(_TaskInfo task) {if (task.status == DownloadTaskStatus.undefined) {return RawMaterialButton(onPressed: () {onAtionClick(task);},child: Icon(Icons.file_download),shape: CircleBorder(),constraints: BoxConstraints(minHeight: 32.0, minWidth: 32.0),);} else if (task.status == DownloadTaskStatus.running) {return RawMaterialButton(onPressed: () {onAtionClick(task);},child: Icon(Icons.pause,color: Colors.red,),shape: CircleBorder(),constraints: BoxConstraints(minHeight: 32.0, minWidth: 32.0),);} else if (task.status == DownloadTaskStatus.paused) {return RawMaterialButton(onPressed: () {onAtionClick(task);},child: Icon(Icons.play_arrow,color: Colors.green,),shape: CircleBorder(),constraints: BoxConstraints(minHeight: 32.0, minWidth: 32.0),);} else if (task.status == DownloadTaskStatus.complete) {return Row(mainAxisSize: MainAxisSize.min,mainAxisAlignment: MainAxisAlignment.end,children: [Text('Ready',style: TextStyle(color: Colors.green),),RawMaterialButton(onPressed: () {onAtionClick(task);},child: Icon(Icons.delete_forever,color: Colors.red,),shape: CircleBorder(),constraints: BoxConstraints(minHeight: 32.0, minWidth: 32.0),)],);} else if (task.status == DownloadTaskStatus.canceled) {return Text('Canceled', style: TextStyle(color: Colors.red));} else if (task.status == DownloadTaskStatus.failed) {return Row(mainAxisSize: MainAxisSize.min,mainAxisAlignment: MainAxisAlignment.end,children: [Text('Failed', style: TextStyle(color: Colors.red)),RawMaterialButton(onPressed: () {onAtionClick(task);},child: Icon(Icons.refresh,color: Colors.green,),shape: CircleBorder(),constraints: BoxConstraints(minHeight: 32.0, minWidth: 32.0),)],);} else if (task.status == DownloadTaskStatus.enqueued) {return Text('Pending', style: TextStyle(color: Colors.orange));} else {return null;}}
}class _TaskInfo {final String name;final String link;String taskId;int progress = 0;DownloadTaskStatus status = DownloadTaskStatus.undefined;_TaskInfo({this.name, this.link});
}class _ItemHolder {final String name;final _TaskInfo task;_ItemHolder({this.name, this.task});
}
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