Flutter文件重下载管理插件re_download的使用

Flutter文件重下载管理插件re_download的使用

在Flutter应用开发过程中，文件下载是一个常见的需求。特别是在网络不稳定或者需要断点续传的情况下，一个强大的文件下载管理插件显得尤为重要。re_download插件正是为了满足这些需求而设计的。本文将详细介绍如何使用re_download插件来实现文件的下载管理。

功能简介

• 下载进度监控：实时查看文件下载的进度。
• 断点续传：支持从断点处继续下载，非常适合视频等大文件的下载。
• 指定下载目录：可以指定下载到某个特定的目录，方便查看和删除。

添加依赖

首先，在你的pubspec.yaml文件中添加re_download插件的依赖：

dependencies:
  re_download: ^1.0.0

然后运行flutter pub get以安装该插件。

基本用法

以下是一个完整的示例代码，展示了如何使用re_download插件来下载文件并监控下载进度。

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

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

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('re_download示例')),
        body: DownloadPage(),
      ),
    );
  }
}

class DownloadPage extends StatefulWidget {
  [@override](/user/override)
  _DownloadPageState createState() => _DownloadPageState();
}

class _DownloadPageState extends State<DownloadPage> {
  String downloadPath = '/storage/emulated/0/Download'; // 指定下载目录
  bool isDownloading = false;
  double downloadProgress = 0.0;

  void startDownload() async {
    setState(() {
      isDownloading = true;
    });

    try {
      await ReDownload.download(
        url: 'https://example.com/video.mp4', // 下载链接
        savePath: '$downloadPath/video.mp4',
        onReceiveProgress: (int count, int total) {
          if (total != -1) {
            setState(() {
              downloadProgress = count / total;
            });
          }
        },
      );
    } catch (e) {
      print('下载失败: $e');
    }

    setState(() {
      isDownloading = false;
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          ElevatedButton(
            onPressed: isDownloading ? null : startDownload,
            child: Text(isDownloading ? '下载中...' : '开始下载'),
          ),
          SizedBox(height: 20),
          LinearProgressIndicator(value: downloadProgress),
          Text('下载进度: ${downloadProgress * 100}%'),
        ],
      ),
    );
  }
}

代码解释

1. 导入必要的库：

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

2. 定义主应用：

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

3. 创建主页面：

   class MyApp extends StatelessWidget {
     [@override](/user/override)
     Widget build(BuildContext context) {
       return MaterialApp(
         home: Scaffold(
           appBar: AppBar(title: Text('re_download示例')),
           body: DownloadPage(),
         ),
       );
     }
   }
   

4. 创建下载页面：

   class DownloadPage extends StatefulWidget {
     [@override](/user/override)
     _DownloadPageState createState() => _DownloadPageState();
   }
   

5. 定义状态类：

   class _DownloadPageState extends State<DownloadPage> {
     String downloadPath = '/storage/emulated/0/Download'; // 指定下载目录
     bool isDownloading = false;
     double downloadProgress = 0.0;
   
     void startDownload() async {
       setState(() {
         isDownloading = true;
       });
   
       try {
         await ReDownload.download(
           url: 'https://example.com/video.mp4', // 下载链接
           savePath: '$downloadPath/video.mp4',
           onReceiveProgress: (int count, int total) {
             if (total != -1) {
               setState(() {
                 downloadProgress = count / total;
               });
             }
           },
         );
       } catch (e) {
         print('下载失败: $e');
       }
   
       setState(() {
         isDownloading = false;
       });
     }
   

6. 构建UI：

   [@override](/user/override)
   Widget build(BuildContext context) {
     return Center(
       child: Column(
         mainAxisAlignment: MainAxisAlignment.center,
         children: <Widget>[
           ElevatedButton(
             onPressed: isDownloading ? null : startDownload,
             child: Text(isDownloading ? '下载中...' : '开始下载'),
           ),
           SizedBox(height: 20),
           LinearProgressIndicator(value: downloadProgress),
           Text('下载进度: ${downloadProgress * 100}%'),
         ],
       ),
     );
   }