Flutter实现APP版本更新

前言：

      Flutter APP打开后检测到有新版本，Android端可以强制更新APK或者跳转到 Google play 官网去下载，iOS端只能去 App Store 官网下载。因为我们的应用是上架到 Google Play，所以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即可。下面我简单总结一下在Flutter中实现“版本更新”的功能。

思路：

1.第一次打开APP时执行"版本更新"的网络请求；

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；

3.弹出“版本更新”对话框；

4.点击"Later"把时间戳保存下来，每次打开APP获取当前时间戳；

5.如果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)；

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

实现的步骤：

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 {
    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
      //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) {
        _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,  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,  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) {
       //如果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 {
    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,  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,  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

      当有新版本需要升级时，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，欢迎大家围观。源码地址: https://github.com/wupeilinloveu/flutter_get_new_version