Flutter文件下载插件file_downloader_android的使用

Flutter文件下载插件file_downloader_android的使用

file_downloader_android 是一个用于在 Flutter 应用中进行文件下载的插件。通过该插件，你可以在 Android 平台上实现文件的下载功能。

使用步骤

1. 添加依赖

   在 pubspec.yaml 文件中添加以下依赖：

   dependencies:
     file_downloader: ^1.0.0
   

2. 初始化插件

   首先需要初始化下载器并设置进度监听器。你可以创建一个类继承自 DownloaderAndroidProgress 来处理进度更新。

   import 'package:file_downloader/api_generated.dart';
   import 'package:file_downloader/file_downloader.dart';
   import 'dart:developer' as developer;
   
   // 设置进度监听器
   DownloaderAndroidProgress.setup(FlutterDownloadProgressImpl());
   
   class FlutterDownloadProgressImpl extends DownloaderAndroidProgress {
   
     FlutterDownloadProgressImpl();
   
     [@override](/user/override)
     void progress(String url, int sofarBytes, int totalBytes) {
       developer.debugPrint("flutter progress:$sofarBytes/$totalBytes");
     }
   }
   

3. 下载文件

   使用 DownloaderAndroid().download 方法来启动文件下载。你需要提供下载 URL 和保存路径。

   void startDownload() async {
     String url = "http://kodo.hss01248.tech/apk/AppManager_v3.1.3.apk?v=2";
     String path = ""; // 空字符串表示默认路径
   
     DownloaderAndroid().download(url, path).then((value) {
       developer.debugPrint(value.toString());
       BaseApiResponse response = BaseApiResponse.fromMap(value);
       if (response.success) {
         developer.debugPrint("下载成功！");
       } else {
         developer.debugPrint("下载失败！");
       }
     }).catchError((error) {
       developer.debugPrint("下载过程中发生错误：$error");
     });
   }
   

4. 取消下载

   如果需要取消正在进行的下载，可以使用 DownloaderAndroid().cancel 方法。同样需要提供下载 URL。

   void cancelDownload() async {
     String url = "http://kodo.hss01248.tech/apk/AppManager_v3.1.3.apk?v=2";
   
     DownloaderAndroid().cancel(url).then((value) {
       developer.debugPrint(value.toString());
       BaseApiResponse response = BaseApiResponse.fromMap(value);
       if (response.success) {
         developer.debugPrint("取消下载成功！");
       } else {
         developer.debugPrint("取消下载失败！");
       }
     }).catchError((error) {
       developer.debugPrint("取消下载过程中发生错误：$error");
     });
   }
   

完整示例代码

以下是一个完整的 Flutter 应用示例，展示了如何使用 file_downloader_android 插件进行文件下载和取消下载。

import 'package:base_api_response_flutter/base_api_response_flutter.dart';
import 'package:file_downloader/api_generated.dart';
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter/services.dart';
import 'package:file_downloader/file_downloader.dart';
import 'flutter_download_progress.dart';

void main() {
  runApp(const MyApp());
  DownloaderAndroidProgress.setup(FlutterDownloadProgressImpl());
}

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

  [@override](/user/override)
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _platformVersion = 'Unknown';
  final _fileDownloaderPlugin = FileDownloader();

  [@override](/user/override)
  void initState() {
    super.initState();
    initPlatformState();
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initPlatformState() async {
    String platformVersion;
    // Platform messages may fail, so we use a try/catch PlatformException.
    // We also handle the message potentially returning null.
    try {
      platformVersion =
          await _fileDownloaderPlugin.getPlatformVersion() ?? 'Unknown platform version';
    } on PlatformException {
      platformVersion = 'Failed to get platform version.';
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      _platformVersion = platformVersion;
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('文件下载插件示例'),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ElevatedButton(
                onPressed: startDownload,
                child: Text("下载 APK"),
              ),
              ElevatedButton(
                onPressed: cancelDownload,
                child: Text("取消下载"),
              )
            ],
          ),
        ),
      ),
    );
  }
}

// 启动下载
void startDownload() async {
  String url = "http://kodo.hss01248.tech/apk/AppManager_v3.1.3.apk?v=2";
  String path = "";

  DownloaderAndroid().download(url, path).then((value) {
    debugPrint(value.toString());
    BaseApiResponse response = BaseApiResponse.fromMap(value);
    if (response.success) {
      debugPrint("下载成功！");
    } else {
      debugPrint("下载失败！");
    }
  }).catchError((error) {
    debugPrint("下载过程中发生错误：$error");
  });
}

// 取消下载
void cancelDownload() async {
  String url = "http://kodo.hss01248.tech/apk/AppManager_v3.1.3.apk?v=2";

  DownloaderAndroid().cancel(url).then((value) {
    debugPrint(value.toString());
    BaseApiResponse response = BaseApiResponse.fromMap(value);
    if (response.success) {
      debugPrint("取消下载成功！");
    } else {
      debugPrint("取消下载失败！");
    }
  }).catchError((error) {
    debugPrint("取消下载过程中发生错误：$error");
  });
}