flutter 版本更新

参考

功能点：

1.更新弹窗UI

2.强更与非强更且别控制

3.屏蔽物理返回键（因为强更的时候点击返回键，弹窗会消失）

4.点击弹窗外透明区域时，弹窗不消失

先看下效果图：



Dialog实现代码：

import 'package:flutter/material.dart';
import 'package:xiaopijiang/utils/assets_util.dart';
import 'package:xiaopijiang/utils/toast_util.dart';

///created by WGH
///on 2020/7/23
///description:版本更新提示弹窗
class UpdateDialog extends Dialog {
 final String upDateContent;
 final bool isForce;

 UpdateDialog({this.upDateContent, this.isForce});

 @override
 Widget build(BuildContext context) {
 return Center(
  child: Column(
  mainAxisAlignment: MainAxisAlignment.center,
  children: <Widget>[
   Container(
   width: 319,
   height: 370,
   child: Stack(
    children: <Widget>[
    Image.asset(
     AssetsUtil.getImagePath(
      imageName: 'bg_update', suffix: 'png'),
     fit: BoxFit.cover,
    ),
    Container(
     width: double.infinity,
     child: Column(
     mainAxisAlignment: MainAxisAlignment.spaceBetween,
     children: <Widget>[
      Container(
      margin: EdgeInsets.only(top: 110),
      child: Text('发现新版本',
       style: TextStyle(
        fontSize: 20,
        color: Colors.white,
        decoration: TextDecoration.none)),
      ),
      Text(upDateContent,
       style: TextStyle(
        fontSize: 16,
        color: Colors.black54,
        decoration: TextDecoration.none)),
      Container(
      width: 250,
      height: 42,
      margin: EdgeInsets.only(bottom: 15),
      child: RaisedButton(
       color: Colors.red,
       shape: StadiumBorder(),
       child: Text(
        '立即更新',
        style:
         TextStyle(fontSize: 20, color: Colors.white),
       ),
       onPressed: () {
        ToastUtil.showTips('下载apk');
       }),
      )
     ],
     ),
    ),
    ],
   ),
   ),
   GestureDetector(
   onTap: () {
    Navigator.pop(context);
   },
   child: Offstage(
    offstage: isForce,
    child: Container(
     margin: EdgeInsets.only(top: 30),
     child: Image.asset(
     AssetsUtil.getImagePath(
      imageName: 'ic_update_close', suffix: 'png'),
     width: 35,
     height: 35,
     )),
   ),
   )
  ],
  ),
 );
 }

 static showUpdateDialog(
  BuildContext context, String mUpdateContent, bool mIsForce) {
 return showDialog(
  barrierDismissible: false,
  context: context,
  builder: (BuildContext context) {
   return WillPopScope(
    child: UpdateDialog(
     upDateContent: mUpdateContent, isForce: mIsForce),onWillPop: _onWillPop);
  });
 }

 static Future<bool> _onWillPop() async{
 return false;
 }
}
调用Dialog：

_checkUpdate() async{
 int serviceVersionCode = 101;
 PackageInfo packageInfo = await PackageInfo.fromPlatform();
 //获取当前的版本号
 int currentVersionCode = int.parse(packageInfo.version.replaceAll('.', ''));
 //如果获取服务器的版本号比当前应用程序的版本号还高，那么提示升级
 if (serviceVersionCode > currentVersionCode) {
  if(Platform.isAndroid){
  //Android平台在应用内进行更新
  //弹出"版本更新"的对话框
  UpdateDialog.showUpdateDialog(context, '1.修复已知bug\n2.优化用户体验', false);
  }else if(Platform.isIOS){
  //iOS平台跳转道AppStore进行更新
  }
 }
 }
重点说明：

屏蔽物理返回键（因为强更的时候点击返回键，弹窗会消失）

barrierDismissible: false,
4.点击弹窗外透明区域时，弹窗不消失

return WillPopScope(
    child: UpdateDialog(
     upDateContent: mUpdateContent, isForce: mIsForce),
    onWillPop: _onWillPop);

 static Future<bool> _onWillPop() async {
 return false;
 }

参考

前言：android

      Flutter的APP打开后检测到有新版本，Android端能够强制更新APK或者跳转到 Google play 官网去下载，iOS端只能去 App Store 官网下载。由于咱们的应用是上架到 Google Play，因此当用户点击下载的按钮，直接跳转到 Google Play 官网或者 App Store 官网去下载APK便可。下面我简单总结一下在Flutter中实现“版本更新”的功能。服务器

思路：网络

1.第一次打开APP时执行"版本更新"的网络请求；app

2.比较服务器的版本号跟当前的版本号，来判断要不要升级APP应用程序；async

3.弹出“版本更新”对话框；ide

4.点击"Later"把时间戳保存下来，每次打开APP获取当前时间戳；ui

5.若是新旧时间戳的差大于或等于一天，执行网络请求(直到点击"DownLoad"为止)；this

6.点击"DownLoad"直接到 Google Play 官网去下载APK。google

实现的步骤：url

1.在pubspec.yaml添加sdk

version: 1.0.2+3  #版本名称:1.0.2  版本号:3

dependencies:
  ...
  cupertino_icons: ^0.1.0
  package_info: ^0.3.2+1
2.导包

import 'package:package_info/package_info.dart';
3.第一次打开APP时执行"版本更新"的网络请求

class UpdatePagerState extends State<UpdaterPage> {
  var _serviceVersionCode,
      _serviceVersionName,
      _serviceVersionPlatform,
      _serviceVersionApp;;

  @override
  void initState() {
    super.initState();
    _getNewVersionAPP();
  }

  //执行版本更新的网络请求
  _getNewVersionAPP() async {
    String url = IHttpService.getNewVersionApp;
    DioUtil.getInstance().get(context, url).then((response) {
      if (response != null) {
        setState(() {
          var data = response.data;
          _serviceVersionCode = data["versionCode"].toString(); //版本号
          _serviceVersionName = data["versionName"].toString(); //版本名称
          _serviceVersionPlatform = data["versionPlatform"].toString();//版本平台
          _serviceVersionApp = data["versionApp"].toString();//下载的url
          _checkVersionCode();
        });
      }
    });
  }

}
4.比较服务器的版本号跟当前的版本号，来判断要不要升级APP应用程序

void _checkVersionCode() {
    PackageInfo.fromPlatform().then((PackageInfo packageInfo) {
      var _currentVersionCode = packageInfo.version;//获取当前的版本号
      int serviceVersionCode = int.parse(_serviceVersionCode); //String -> int
      int currentVersionCode = int.parse(_currentVersionCode); //String -> int
      //若是获取服务器的版本号比当前应用程序的版本号还高，那么提示升级
      if (serviceVersionCode > currentVersionCode) {
        _showNewVersionAppDialog();//弹出"版本更新"的对话框
      }
   });
}
5.弹出“版本更新”对话框

Future<void> _showNewVersionAppDialog() async {
    if (_serviceVersionPlatform == "android") {
     return showDialog<void>(
        context: context,
        barrierDismissible: false,
        builder: (BuildContext context) {
          return AlertDialog(
            title: new Row(
              children: <Widget>[
                new Image.asset("images/ic_launcher_icon.png",
                    height: 35.0, width: 35.0),
                new Padding(
                    padding: const EdgeInsets.fromLTRB(30.0, 0.0, 10.0, 0.0),
                    child: new Text("项目名称",
                        style: dialogButtonTextStyle))
              ],
            ),
            content: new Text(
                '版本更新',
                style: dialogTextStyle),
            actions: <Widget>[
              new FlatButton(
                child: new Text('Later', style: dialogButtonTextStyle),
                onPressed: () {
                  Navigator.of(context).pop();
                },
              ),
              new FlatButton(
                child: new Text('DownLoad', style: dialogButtonTextStyle),
                onPressed: () {
                  //https://play.google.com/store/apps/details?id=项目包名
                  launch(_serviceVersionApp);//到Google Play 官网下载
                  Navigator.of(context).pop();              
                },
              )
            ],
          );
        });
    }else{
     //iOS
     return showDialog<void>(
        context: context,
        barrierDismissible: false,
        builder: (BuildContext context) {
          return CupertinoAlertDialog(
            title: new Row(
              children: <Widget>[
                new Image.asset("images/ic_launcher_icon.png",
                    height: 35.0, width: 35.0),
                new Padding(
                    padding: const EdgeInsets.fromLTRB(30.0, 0.0, 10.0, 0.0),
                    child: new Text(Strings.new_version_title,
                        style: dialogButtonTextStyle))
              ],
            ),
            content: new Text(
                "New version v$_serviceVersionName is available. " +
                    Strings.new_version_dialog_content,
                style: dialogTextStyle),
            actions: <Widget>[
              new CupertinoDialogAction(
                child: new Text(Strings.new_version_button_later,
                    style: dialogButtonTextStyle),
                onPressed: () {
                  Navigator.of(context).pop();                 
                },
              ),
              new CupertinoDialogAction(
                child: new Text(Strings.new_version_button_download,
                    style: dialogButtonTextStyle),
                onPressed: () {
                  //_serviceVersionApp="http://itunes.apple.com/cn/lookup?id=项目包名"
                  launch(_serviceVersionApp);//到APP store 官网下载
                  Navigator.of(context).pop();
                },
              )
            ],
          );
        });
    } 
  }
6.完整的代码

class UpdaterPage extends StatefulWidget {
  final Widget child;

  const UpdaterPage(this.child);

  @override
  UpdatePagerState createState() => UpdatePagerState();
}

class UpdatePagerState extends State<UpdaterPage> {
  var _serviceVersionCode,
      _serviceVersionName,
      _serviceVersionPlatform,
      _serviceVersionApp;

  @override
  void initState() {
    super.initState();
    //每次打开APP获取当前时间戳
    var timeEnd = DateTime.now().millisecondsSinceEpoch;
    //获取"Later"保存的时间戳
    var timeStart = SpUtil.getInt(Constants.timeStart);
    if (timeStart == 0) {//第一次打开APP时执行"版本更新"的网络请求
      _getNewVersionAPP();
    } else if (timeStart != 0 && timeEnd - timeStart >= 24 * 60 * 60 * 1000) {
       //若是新旧时间戳的差大于或等于一天，执行网络请求
      _getNewVersionAPP();
    }
  }

  //执行版本更新的网络请求
  _getNewVersionAPP() async {
    String url = IHttpService.getNewVersionApp;
    DioUtil.getInstance().get(context, url).then((response) {
      if (response != null) {
        setState(() {
          var data = response.data;
          _serviceVersionCode = data["versionCode"].toString();//版本号
          _serviceVersionName = data["versionName"].toString();//版本名称
          _serviceVersionPlatform = data["versionPlatform"].toString();//版本平台
          _serviceVersionApp = data["versionApp"].toString();//下载的URL
          _checkVersionCode();
        });
      }
    });
  }

  //检查版本更新的版本号
  _checkVersionCode() async {
    PackageInfo packageInfo = await PackageInfo.fromPlatform();
    String _currentVersionCode = packageInfo.version;
    int serviceVersionCode = int.parse(_serviceVersionCode); //String -> int
    int currentVersionCode = int.parse(_currentVersionCode); //String -> int
    if (serviceVersionCode > currentVersionCode) {
      _showNewVersionAppDialog();//弹出对话框
    }
  }

 //弹出"版本更新"对话框
 Future<void> _showNewVersionAppDialog() async {
    if (_serviceVersionPlatform == "android") {
     return showDialog<void>(
        context: context,
        barrierDismissible: false,
        builder: (BuildContext context) {
          return AlertDialog(
            title: new Row(
              children: <Widget>[
                new Image.asset("images/ic_launcher_icon.png",
                    height: 35.0, width: 35.0),
                new Padding(
                    padding: const EdgeInsets.fromLTRB(30.0, 0.0, 10.0, 0.0),
                    child: new Text("项目名称",
                        style: dialogButtonTextStyle))
              ],
            ),
            content: new Text(
                '版本更新',
                style: dialogTextStyle),
            actions: <Widget>[
              new FlatButton(
                child: new Text('Later', style: dialogButtonTextStyle),
                onPressed: () {
                  Navigator.of(context).pop();
                  var timeStart = DateTime.now().millisecondsSinceEpoch;
                  DataUtil.saveCurrentTimeMillis(timeStart);//保存当前的时间戳
                },
              ),
              new FlatButton(
                child: new Text('DownLoad', style: dialogButtonTextStyle),
                onPressed: () {
                  //https://play.google.com/store/apps/details?id=项目包名
                  launch(_serviceVersionApp);//到Google Play 官网下载
                  Navigator.of(context).pop();              
                },
              )
            ],
          );
        });
    }else{
     //iOS
     return showDialog<void>(
        context: context,
        barrierDismissible: false,
        builder: (BuildContext context) {
          return CupertinoAlertDialog(
            title: new Row(
              children: <Widget>[
                new Image.asset("images/ic_launcher_icon.png",
                    height: 35.0, width: 35.0),
                new Padding(
                    padding: const EdgeInsets.fromLTRB(30.0, 0.0, 10.0, 0.0),
                    child: new Text(Strings.new_version_title,
                        style: dialogButtonTextStyle))
              ],
            ),
            content: new Text(
                "New version v$_serviceVersionName is available. " +
                    Strings.new_version_dialog_content,
                style: dialogTextStyle),
            actions: <Widget>[
              new CupertinoDialogAction(
                child: new Text(Strings.new_version_button_later,
                    style: dialogButtonTextStyle),
                onPressed: () {
                  Navigator.of(context).pop();
                  var timeStart = DateTime.now().millisecondsSinceEpoch;
                  DataUtil.saveCurrentTimeMillis(timeStart);//保存当前的时间戳                 
                },
              ),
              new CupertinoDialogAction(
                child: new Text(Strings.new_version_button_download,
                    style: dialogButtonTextStyle),
                onPressed: () {
                  //_serviceVersionApp="http://itunes.apple.com/cn/lookup?id=项目包名"
                  launch(_serviceVersionApp);//到APP store 官网下载
                  Navigator.of(context).pop();
                },
              )
            ],
          );
        });
    } 
  }

  @override
  Widget build(BuildContext context) => widget.child;
}
7.在首页调用”版本更新”的类

class IndexPage extends StatefulWidget {
  @override
  IndexPageState createState() => IndexPageState();
}
 
class IndexPageState extends State<IndexPage>{
  @override
  Widget build(BuildContext context) {
     return UpdaterPage(Scaffold( //调用UpdaterPage
      appBar: _buildAppBar(),
      body: getScreen()
    ));
  }
}
8.总结

      当有新版本须要升级时，客户端会"版本更新"弹出对话框，Android用户跳转到 Google Play 官网去下载APK,而iOS用户跳转到 App Store 官网下载。APP版本更新的功能已经实现，欢迎你们围观。若是有什么疑问的话，能够留言联系我哦！

参考

升级说明：
Android：应用内更新下载+安装。iOS：跳转到appstore下载安装。
注：可以通过热更新技术进行升级（我不会）。
引用插件：

  #获取当前版本
  package_info: ^0.4.3+2
  #版本内更新
  ota_update: ^2.4.1
  #网页打开工具
  url_launcher: ^5.7.10
  #事件车
  event_bus: ^1.1.1
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直接上代码：

class VersionUpdate {
  ///检查是否需要更新
  ///是否需要升级--判断
  static Future<bool> isUpdating() async {
    PackageInfo packageInfo = await PackageInfo.fromPlatform();
    String localVersion = packageInfo.version;
    SpUtil.putString('localVersion', localVersion);
    ApiResponse<VersionEntity> res =
        await PersonalCenterAPI.updatingVersion(versionNo: packageInfo.version);
    if (res.status == Status.COMPLETED) {
      //如果获取服务器的版本号与当前应用程序的版本号对比，，不等那么提示升级(判断条件修改为符合自己的)
      SpUtil.putObject('netVersionInfo', res.data.toJson());
      if (res.data.currentVersion != localVersion) {
        BottomSheetDialog.overLayDialog();
      }
    }
    //return isUpdating;
  }

  ///android--去android应用内下载更新  ---ios跳去App Store
  static downloadNewVersion({String Url}) async {
    if (Platform.isIOS) {
      String url = Url;
      if (await canLaunch(url)) {
        await launch(url);
      } else {
        throw 'Could not launch $url';
      }
    } else if (Platform.isAndroid) {
      String url = Url;
      try {
        // destinationFilename 是对下载的apk进行重命名
        OtaUpdate().execute(url, destinationFilename: 'gzzoc.apk').listen(
          (OtaEvent event) {
            switch (event.status) {
              case OtaStatus.DOWNLOADING: // 下载中
                //TestEventBus().bus.fire(ProgressEvent(data: event.value));
                ProgressEventBus().bus.fire(ProgressEvents(data: event.value));
                print('status:${event.status},value:${event.value}');
                break;
              case OtaStatus.INSTALLING: //安装中
                break;
              case OtaStatus.PERMISSION_NOT_GRANTED_ERROR: // 权限错误
                print('更新失败');
                break;
              default: // 其他问题
                break;
            }
          },
        );
      } catch (e) {
        print('更新失败');
      }
    }
  }
}
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overLayDialog

overLayDialog() {
    OverlayState overlayState = Application.globalKey.currentState.overlay;
    OverlayEntry overlayEntry;
    overlayEntry = new OverlayEntry(builder: (context) {
      return OverLayDialog(
        overlayEntry: overlayEntry,
      );
    });
    overlayState.insert(overlayEntry);
  }
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OverLayDialog名字太像了（忘记改了）

class OverLayDialog extends StatefulWidget {
 final OverlayEntry overlayEntry;

 OverLayDialog({this.overlayEntry});

 @override
 _OverLayDialogState createState() => _OverLayDialogState();
}

class _OverLayDialogState extends State<OverLayDialog> {
 VersionEntity _netVersionInfo;
 String _progress;
 @override
 void initState() {
   // TODO: implement initState
   super.initState();
   _netVersionInfo =
       VersionEntity.fromJson(SpUtil.getObject('netVersionInfo'));
   ProgressEventBus().bus.on<ProgressEvents>().listen((event) {
     if (!mounted) return;
     setState(() {
       _progress = event.data;
     });
   });
 }

 @override
 Widget build(BuildContext context) {
   return Material(
     color: MyColors.black_cc00,
     child: Container(
         margin: EdgeInsets.symmetric(horizontal: 40),
         child: Center(
           child: Column(
             mainAxisSize: MainAxisSize.min,
             children: [
               Stack(
                 alignment: Alignment.bottomCenter,
                 children: [
                   Stack(
                     children: [
                       Image.asset(
                         'assets/images/version_update.png',
                       ),
                       Container(
                         margin: EdgeInsets.only(top: 60),
                         padding: EdgeInsets.symmetric(horizontal: 20),
                         child: Column(
                           crossAxisAlignment: CrossAxisAlignment.start,
                           children: [
                             Text(
                               '发现新版本',
                               style: TextStyle(
                                   color: MyColors.white,
                                   fontWeight: FontWeight.bold,
                                   fontSize: 21),
                             ),
                             Text('版本：${_netVersionInfo.currentVersion}',
                                 style: TextStyle(
                                     color: MyColors.white, fontSize: 16)),
                             Container(
                               height: MediaQuery.of(context).size.height / 3,
                               padding: EdgeInsets.only(top: 22, bottom: 22),
                               child: ListView.builder(
                                   // itemCount: _content.length,
                                   itemCount: _netVersionInfo?.description
                                       ?.split(';')
                                       ?.length,
                                   itemBuilder: (context, index) {
                                     return Padding(
                                       padding:
                                           EdgeInsets.symmetric(vertical: 7),
                                       child: Text(
                                         _netVersionInfo?.description
                                             ?.split(';')[index],
                                         style: TextStyle(
                                             color: MyColors.white,
                                             fontSize: 15),
                                       ),
                                     );
                                   }),
                             )
                           ],
                         ),
                       ),
                     ],
                   ),
                   Column(
                     children: [
                       _progress == null
                           ? SizedBox.shrink()
                           : Text(
                               '$_progress%',
                               style: TextStyle(
                                   color: MyColors.white, fontSize: 12),
                             ),
                       InkWell(
                         onTap: () {
                           if (_progress == null) {
                             VersionUpdate.downloadNewVersion(
                                 Url: _netVersionInfo?.url);
                             //'https://itunes.apple.com/cn/app/id414478124'
                           }
                         },
                         child: Container(
                           margin: EdgeInsets.only(
                               left: 20, right: 20, top: 5, bottom: 15),
                           decoration: BoxDecoration(
                             color: MyColors.white,
                             borderRadius:
                                 BorderRadius.all(Radius.circular(50)),
                           ),
                           child: Row(
                             mainAxisAlignment: MainAxisAlignment.center,
                             children: [
                               Container(
                                 padding: EdgeInsets.symmetric(vertical: 10),
                                 child: Text(
                                   '立刻升级',
                                   style: TextStyle(
                                       color: MyColors.yellow_17,
                                       fontSize: 17,
                                       fontWeight: FontWeight.bold),
                                 ),
                               )
                             ],
                           ),
                         ),
                       )
                     ],
                   )
                 ],
               ),
               SizedBox(
                 height: 14,
               ),
               _netVersionInfo?.forceFlag == '1'
                   ? SizedBox.shrink()
                   : InkWell(
                       onTap: () {
                         widget?.overlayEntry?.remove();
                       },
                       child: Icon(
                         Icons.cancel_outlined,
                         color: MyColors.white,
                         size: 30,
                       ),
                     )
             ],
           ),
         )),
   );
 }
}
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使用：我是在闪屏页的初始化中调用的，按照自己的需求改就行
   //版本更新
   VersionUpdate.isUpdating();
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说明：SpUtil.putString是个工具，就是存储本地版本号而已，改SharedPreferences去存就行。
Application.globalKey.currentState.overlay：

class Application {
  /// 全局key
  static final GlobalKey<NavigatorState> globalKey =
      GlobalKey<NavigatorState>();
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注：适合刚入门看。缺少什么或者不懂的可以留言我补。刚接触flutter不久，各位指导指导。
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版权声明：本文为CSDN博主「_诸葛青」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/C201624141155/article/details/113759869

参考

//开始检测按钮
ElevatedButton(
    onPressed: () {
        //__getPackageInfo()返回值是Future，用then拆开获得当前版本号
        _getPackageInfo().then((value) {
            //当前版本号赋值给version，最新版本号暂设置在全局newVersion
            version = value;
            //引用CheckVersion类比较当前版本号和最新版本号大小
            CheckVersion.isNewVersion(version, newVersion)
                ? _needUpdate()//需要更新
                : _needNotUpdate();//不需要更新
        });
    },
    child: Text('检测新版本'),
),
//返回当前版本号
_getPackageInfo() async {
    PackageInfo packageInfo = await PackageInfo.fromPlatform();
    String version = packageInfo.version;
    return version;
}

是否需要更新
//需要更新Dialog
void _needUpdate() async {
    await showDialog(
        context: context,
        builder: (context) {
            return AlertDialog(
                title: Text("版本检测!"),
                content: Text("发现新的版本，是否更新!"),
                actions: <Widget>[
                    TextButton(
                        child: Text("否"),
                        onPressed: () {
                            Navigator.pop(context);
                        },
                    ),
                    TextButton(
                        child: Text("是"),
                        onPressed: () {
                            _downLoad();//引用下载方法
                            Navigator.pop(context);//取消dialog
                        })
                ],
            );
        });
}
//不需要更新Dialog
_needNotUpdate() async {
    await showDialog(
        context: context,
        builder: (context) {
            return AlertDialog(
                title: Text('版本检测'),
                content: Text('无需更新，已是最新版本！'),
                actions: [
                    TextButton(
                        child: Text("好"),
                        onPressed: () {
                            Navigator.pop(context, 'Cancle');//取消dialog
                        },
                    ),
                ],
            );
        });
}
开始执行下载方法
 //下载打开文件
  _downLoad() async {
    var permission = await this._checkPermission();//检测是否有权限
      //如果有权限，配置安装路径
    if (permission) {
      Directory? directory = await getExternalStorageDirectory();
      String? _localPath;
      //注意Flutter2.2以后的版本加入了Null safety
      if (directory != null) {
        _localPath = directory.path;
        String _appName = "app-release.apk";
        String _savePath = "$_localPath/$_appName";
        String apkUrl = "https://www.tobutomi.top/app/app-release.apk";
         //实例化Dio网络请求库
        Dio dio = new Dio();
          //实例化下载进度Dialog库
        ProgressDialog pd = ProgressDialog(context: context);
        pd.show(max: 100, msg: '正在下载...');
          //使用dio.download进行下载
        await dio.download(apkUrl, _savePath,
            onReceiveProgress: (received, total) {
         //下载进度
          int progress = (((received / total) * 100).toInt());
          pd.update(value: progress);
        });
        await OpenFile.open(_savePath,
            type: "application/vnd.android.package-archive");
      } else {
        print("获取目录失败");
      }
    } else {
      print("没有权限");
    }
  }
//检查权限_checkPermission
Future<bool> _checkPermission() async {
    if (Theme.of(context).platform == TargetPlatform.android) {
        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;
        }
    }
    return false;
}
完整代码
CheckVersion工具类
class CheckVersion {
    static bool isNew = false;
    static isNewVersion(version, newversion) {
        List verList = version.split('.');
        List newVerList = newversion.split('.');
        if (int.parse(newVerList[0]) > int.parse(verList[0])) {
            isNew = true;
        } else if (int.parse(newVerList[0]) == int.parse(verList[0])) {
            if (int.parse(newVerList[1]) > int.parse(verList[1])) {
                isNew = true;
            } else if (int.parse(newVerList[1]) == int.parse(verList[1])) {
                if (int.parse(newVerList[2]) > int.parse(verList[2])) {
                    isNew = true;
                }
            }
        }
        return isNew;
    }
}

主页代码
import 'package:flutter/material.dart';
import 'package:package_info_plus/package_info_plus.dart';
import 'package:path_provider/path_provider.dart';
import 'dart:io';
import 'package:open_file/open_file.dart';
import 'package:dio/dio.dart';
import 'package:permission_handler/permission_handler.dart';
import '../../components/CheckVersion.dart';
import 'package:sn_progress_dialog/sn_progress_dialog.dart';

class AppVersionPage extends StatefulWidget {
    AppVersionPage({Key? key}) : super(key: key);
    _AppVersionPageState createState() => _AppVersionPageState();
}

class _AppVersionPageState extends State<AppVersionPage> {
    //设置新版本号，可以存于云端
    var newVersion = '1.0.0';
    var version;
    //需要更新
    void _needUpdate() async {
        await showDialog(
            context: context,
            builder: (context) {
                return AlertDialog(
                    title: Text("版本检测!"),
                    content: Text("发现新的版本，是否更新!"),
                    actions: <Widget>[
                        TextButton(
                            child: Text("否"),
                            onPressed: () {
                                Navigator.pop(context);
                            },
                        ),
                        TextButton(
                            child: Text("是"),
                            onPressed: () {
                                _downLoad();
                                Navigator.pop(context);
                            })
                    ],
                );
            });
    }

    //不需要更新
    _needNotUpdate() async {
        await showDialog(
            context: context,
            builder: (context) {
                return AlertDialog(
                    title: Text('版本检测'),
                    content: Text('无需更新，已是最新版本！'),
                    actions: [
                        TextButton(
                            child: Text("好"),
                            onPressed: () {
                                Navigator.pop(context, 'Cancle');
                            },
                        ),
                    ],
                );
            });
    }

    //获取版本号
    _getPackageInfo() async {
        PackageInfo packageInfo = await PackageInfo.fromPlatform();
        String version = packageInfo.version;
        return version;
    }

    //检查权限
    Future<bool> _checkPermission() async {
        if (Theme.of(context).platform == TargetPlatform.android) {
            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;
            }
        }
        return false;
    }

    //下载打开文件
    _downLoad() async {
        var permission = await this._checkPermission();

        if (permission) {
            Directory? directory = await getExternalStorageDirectory();
            String? _localPath;
            //注意Flutter2.2以后的版本加入了Null safety
            if (directory != null) {
                _localPath = directory.path;
                String _appName = "aaa.apk";
                String _savePath = "$_localPath/$_appName";
                String apkUrl = "https://www.tobutomi.top/app/app-release.apk";

                Dio dio = new Dio();
                ProgressDialog pd = ProgressDialog(context: context);
                pd.show(max: 100, msg: '正在下载...');
                await dio.download(apkUrl, _savePath,
                                   onReceiveProgress: (received, total) {
                                       int progress = (((received / total) * 100).toInt());
                                       pd.update(value: progress);
                                   });
                await OpenFile.open(_savePath,
                                    type: "application/vnd.android.package-archive");
            } else {
                print("获取目录失败");
            }
        } else {
            print("没有权限");
        }
    }

    @override
    Widget build(BuildContext context) {
        return Scaffold(
            appBar: AppBar(
                title: Text("app升级演示"),
            ),
            body: Center(
                child: ElevatedButton(
                    onPressed: () {
                        _getPackageInfo().then((value) {
                            version = value;
                            CheckVersion.isNewVersion(version, newVersion)
                                ? _needUpdate()
                                : _needNotUpdate();
                        });
                    },
                    child: Text('检测新版本'),
                ),
            ),
        );
    }
}