Flutter 实现 App 内更新安装包

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_downloader/flutter_downloader.dart';
import 'package:package_info/package_info.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:url_launcher/url_launcher.dart';
 
class AppUpdatePage extends StatefulWidget {
  @override
  _AppUpdatePageState createState() => _AppUpdatePageState();
}
 
class _AppUpdatePageState extends State<AppUpdatePage> {
  String _latestVersion = 'Unknown';
  String _downloadUrl = '';
  String _currentVersion = 'Unknown';
  bool _isDownloading = false;
 
  @override
  void initState() {
    super.initState();
    _getLatestVersion();
    _requestPermissions();
    _initDownloader();
  }
 
  // 获取最新版本信息
  Future<void> _getLatestVersion() async {
    final packageInfo = await PackageInfo.fromPlatform();
    setState(() {
      _currentVersion = packageInfo.version;
    });
    // 这里应该是获取服务器最新版本信息的逻辑
    // ...
    setState(() {
      _latestVersion = '服务器最新版本';
      _downloadUrl = '下载地址';
    });
  }
 
  // 请求权限
  Future<void> _requestPermissions() async {
    // 请求存储权限
    await Permission.storage.request();
  }
 
  // 初始化下载器
  Future<void> _initDownloader() async {
    Downloader.initialize(
        debug: false, // 是否启用Log
        callback: (id, status, progress) {
          // 下载进度回调
        }
    );
  }
 
  // 下载apk
  Future<void> _downloadApk() async {
    final dir = await getExternalStorageDirectory();
    final savedDir = '$dir/.downloads';
    try {
      setState(() {
        _isDownloading = true;
      });
      int result = await Downloader.enqueue(
        url: _downloadUrl,
        savedDir: savedDir,
        fileName: 'update.apk',
        showNotification: true, // 是否显示下载通知
        openNotification: true, // 是否自动打开下载完成的通知
      );
      print('下载任务ID: $r