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dart - Flutter 如何将数据列表保存到本地存储

问题描述

我正在开发关于颤振的电影发现应用程序，我需要将正在播放的电影列表保存在本地存储中以供离线使用，那么我该如何做到这一点 Future> getNowPlayingMovies() async { final String nowPlaying = ' https://api. themoviedb.org/3/tv/airing_today?api_key='+'$myapikey'+'&page='+'1 '；

var httpClient = new HttpClient();
try {
  // Make the call
  var request = await httpClient.getUrl(Uri.parse(nowPlaying));
  var response = await request.close();
  if (response.statusCode == HttpStatus.OK) {
    var jsonResponse = await response.transform(utf8.decoder).join();
    // Decode the json response
    var data = jsonDecode(jsonResponse);
    // Get the result list
    List results = data["results"];
    print(results);
    // Get the Movie list
    List<moviemodel> movieList = createNowPlayingMovieList(results);
    // Print the results.
    return movieList;
  } else {
    print("Failed http call.");
  }
} catch (exception) {
  print(exception.toString());
}
return null;}



  List<moviemodel> createNowPlayingMovieList(List data) {
List<Searchmodel> list = new List();
for (int i = 0; i < data.length; i++) {
  var id = data[i]["id"];
  String title = data[i]["name"];
  String posterPath = data[i]["poster_path"];
  String mediatype = data[i]["media_type"];

  moviemodel movie = new moviemodel(id, title, posterPath, mediatype);
  list.add(movie);
}
return list; }



List<Widget> createNowPlayingMovieCardItem(
  List<moviemodel> movies, BuildContext context) {
// Children list for the list.
List<Widget> listElementWidgetList = new List<Widget>();
if (movies != null) {
  var lengthOfList = movies.length;
  for (int i = 0; i < lengthOfList; i++) {
    Searchmodel movie = movies[i];
    // Image URL
    var imageURL = "https://image.tmdb.org/t/p/w500/" + movie.posterPath;
    // List item created with an image of the poster
    var listItem = new Padding(
      padding: const EdgeInsets.all(8.0),
      child: new Container(
        width: 105.0,
        height: 155.0,
        child: new Column(
          children: <Widget>[
            new GestureDetector(
              onTap: () {
                Navigator.push(
                  context,
                  new MaterialPageRoute(
                      builder: (_) => new Detail(movie.id)),
                );
              },
              child: new Container(
                width: 105.0,
                height: 155.0,
                child: new ClipRRect(
                  borderRadius: new BorderRadius.circular(7.0),
                  child: new Hero(
                    tag: movie.title,
                    child: new FadeInImage.memoryNetwork(
                      placeholder: kTransparentImage,
                      image: imageURL,
                      fit: BoxFit.cover,
                    ),
                  ),
                ),
                decoration: new BoxDecoration(boxShadow: [
                  new BoxShadow(
                      color: Colors.black12,
                      blurRadius: 10.0,
                      offset: new Offset(0.0, 10.0)),
                ]),
              ),
            ),
            new Padding(
              padding: const EdgeInsets.only(top: 18.0),
              child: new Text(
                movie.title,
                maxLines: 2,
              ),
            )
          ],
        ),
      ),
    );
    ;
    listElementWidgetList.add(listItem);
  }
} else {
  print("no movie search");
}
return listElementWidgetList;}

谢谢你！

标签： dartflutter

解决方案

使用path_provider：

  1. 找到正确的本地路径：
    未来获取 _localPath 异步 {
      最终目录 = 等待 getApplicationDocumentsDirectory();
      返回目录.路径；
    }
  1. 创建对文件位置的引用
    未来获取 _localFile 异步 {
      最终路径 = 等待 _localPath；
      返回文件('$path/yourfile.txt');
    }
  1. 将数据写入文件：
    未来 writeCounter(int counter) async {
      最终文件 = 等待 _localFile；

      // 写入文件
      return file.writeAsString('blah bla blah');
    }
  1. 从文件中读取数据：
    未来的 readCounter() 异步 {
      尝试 {
        最终文件 = 等待 _localFile；

        // 读取文件
        字符串内容 = 等待 file.readAsString();

        返回 int.parse(内容);
      } 抓住 (e) {
        // 如果遇到错误，返回 0
        返回0；
      }
    }

如果你打印contents= "blah blah blah"

文档：https ://flutter.io/cookbook/persistence/reading-writing-files/

File 有很多方法可以帮助你，结帐：

https://docs.flutter.io/flutter/dart-io/File-class.html

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